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  • 1. By Omar Zeidan
  • 2. Table of ContentsTABLE OF CONTENTS PREFACE ……………………………………………………………….... FOREWORD ……………………………………………………………… INTRODUCTION ……………………………………………………… PLANT MORPHOLOGY ……………………………………………… CLIMATIC FACTORS AND THEIR INFLUENCE ON TOMATOES……. GREENHOUSES FOR TOMATO PRODUCTION ………………………. NET HOUSES FOR TOMATO PRODUCTION ………………………….. GREENHOUSE COVERING FILMS………………………………… PREPARATION FOR NEW CROP………………………………… IMPROVING CLIMATE CONDITIONS IN SUMMER AND AUTUMN…… SEEDS, SEEDLING PREPARATION AND TRANSPLANTING………… TRAINING METHODS……………………………………………………… PLANTING SEASONS……………………………………………………… TABLE TOMATO VARIETIES……………………………………… CHERRY TOMATO VARIETIES……………………………………… GROWING TOMATOES FOR CLUSTER HARVESTING………………… NEW TOMATO PRODUCTS………………………………………………… PARTIAL RESISTANCE TO ROOT KNOT NEMATODES………………… ROOTSTOCK AND GRAFTING…………………………………………… POLLINATION AND FRUIT SET OF GREENHOUSE TOMATOES…… IRRIGATION AND NUTRITION…………………………………………… MICROELEMENT DEFICIENCY IN TOMATO PLANTS…………………… SOIL SALINITY………………………………………………………………… GROWING TOMATOES IN SUBSTRATES (Soilless Culture)………… RECYCLING DRAINAGE WATER …………………………………………. GREENHOUSE VENTILATION……………………………………… GREENHOUSE HEATING…………………………………………… CO2 ENRICHMENT FOR TOMATOES………………………………… ETHYLENE DAMAGE……………………………………………………… GROWTH AND FRUIT DISORDERS……………………………………… TOMATO HARVESTING AND POSTHARVEST………………………… ETHERAL TREATMENT TO ACCELERATE TOMATO RIPENING…… OVER VIEW OF ORGANIC PRODUCTION OF TOMATOES………… DISEASE AND PEST CONTROL…………………………………………… CHEMICAL SPRAY APPLICATION TECHNOLOGIES………………… NON-PARASITIC DISORDERS……………………………………… WEEDS AND PARASITIC PLANTS……………………………………… SOIL-BORNE DISEASES…………………………………………… TOMATO LEAF DISEASES…………………………………………… BACTERIAL DISEASES…………………………………………… VIRAL DISEASES………………………………………………………… PESTS…………………………………………………………………… BIBLIOGRAPHY…………………………………………………………… i ii 1 2 5 7 10 10 12 15 18 20 23 24 27 29 30 34 34 36 41 46 48 50 57 58 59 61 61 62 66 71 72 74 76 78 80 81 83 88 89 93 97 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40.
  • 3. PrefacePREFACE High-quality vegetable production, particularly tomatoes, holds an important part in the global fresh horticultural food basket. We therefore feel the need to transfer and adapt the knowledge and technology that has been compiled in this field in Israel and make it available to English- speaking agricultural extensionists, specialists, growers and entrepreneurs. Tomato production has special relevance to the Mediterranean and Middle East countries. The compilation of this publication can be used as professional input for the regional Middle East and Mediterranean Program of Integrated Crop Management initiated by the Peres Center for Peace in cooperation with countries in the region. Tomato production and post-harvest care are a priority in the activities of its cooperation programs. The newly published publication, Tomato Production Under Protected Conditions, was written by Mr. Omar Zeidan, Director, Vegetable Growing Department and Assistant Deputy-Director of the Extension Service, Ministry of Agriculture and Rural Development, in 2001. Mr. Zeidan is also recognized as a highly experienced tomato specialist in international circles. This manual was translated from the original Hebrew document of the Extension Service of the Israel Ministry of Agriculture and Rural Development. The professional strength and relevancy of the topic motivated and initiated the parties, MASHAV, CINADCO and the Peres Center for Peace, through the Andreas Agricultural Development Trust, to publish the manual in its English version. The publishers wish to acknowledge and thank the Extension Service of the Israel Ministry of Agriculture and Rural Development for their professional contribution and cooperation in this endeavour. We envisage that this publication will contribute to the production of high- quality produce resulting in increased farm income and economic growth. We also hope that Tomato Production Under Protected Conditions will enhance the sharing of know-how as a means of strengthening the professional and people-to-people links of the countries in the region and beyond. i Zvi Herman Director CINADCO Ministry of Agriculture and Rural Development Prof. Samuel Pohoryles Director The Andreas Agricultural Development Trust The Peres Center for Peace Moshe Goren Director Extension Service Ministry of Agriculture and Rural Development
  • 4. ii ForewordFOREWORD This manual is intended for professionals and farmers involved in greenhouse tomato growing and marketing, locally and/or for export. The manual includes principles of tomato growing in order to help the growers understand the basic stages that guarantee a successful crop. The material in this manual is based on technological knowledge and experience that has been accumulated in Israel over the years for the better use of greenhouses, nurseries and net houses for tomato production. The chapters in this manual are written according to the order of stages recommended in establishing a new greenhouse project and according to the order of activities in growing tomatoes, from the planning stage until the final growing stages. The agro-technical instructions, planting times, fertilization, irrigation, pollination and other activities are based on numerous research findings and field tests that were conducted at various sites throughout Israel. Research institutions, scientists, extension workers and growers participated in and contributed to the establishment of this advanced agro-technological branch. Thus, this manual includes professional and scientific principles that can provide basic training for students, support for field extension staff and guidelines for marketers of agricultural output in Israel and in countries throughout the world that participate in Israel’s international cooperation programs. We are happy to share the professional material presented here, however, we wish to point out that these are recommendations only and should not take the place of detailed and certified local engineering planning. It is my pleasure to thank CINADCO, The Centre for International Agricultural Development Cooperation of the Ministry of Foreign Affairs and the Ministry of Agriculture and Rural Development, the Peres Center for Peace, through the Andreas Agricultural Development Trust and the many experts and professional staff of the Israel Ministry of Agriculture and Rural Development, Extension Service, who read the draft of this manual and submitted their helpful comments in order to make this publication possible. Director, Vegetable Growing Dept. and Deputy Director, Extension Service, Ministry of Agriculture and Rural Development Omar Zeidan
  • 5. 1 Common name: Tomato Scientific name: Lycopersicon esculentum Mill. Family: Solanaceae The tomato plant originated in Peru and Mexico, in present day Central and South America. The tomato reached Europe from Mexico in the 16th Century, and was initially used as an ornamental plant. At the end of the 18th Century, the tomato started to be produced as an edible cultivated plant for household use. The tomato only reached Israel in the 19th Century. Tomato production is currently considered to be one of the main vegetable crops, and constitutes an economic force that influences the income of many growers in the world. In Israel, tomatoes used to be planted in greenhouses in the fall, especially in the western Negev desert, with the aim of developing tomato production for export to Europe and other destinations. This crop was characterized by a limited yield season from December to March. However, technological developments and innovative growing methods expanded crop production to other areas in Israel and is now year round in greenhouses and net- houses. Contamination of open-field tomato plants by tomato yellow leaf curl virus (TYLCV) requires intensive and multiple spraying against Bemisia tabaci (whitefly). This encouraged transition to growing of tomatoes under protected conditions, in both greenhouses and net houses. The conventional production methods in Israel, which are described in this booklet, are similar to conventional methods applied in many Mediterranean and Latin American countries. Therefore, the recommendations in this booklet may be useful for growers in these countries. Export of regular tomatoes from Israel has recently declined, due to the large supply of tomatoes in international markets from supply sources that are close to the European markets, such as Spain, Morocco and other Mediterranean countries. Since tomato production targeted for the export market is a source of livelihood for many farmers, in order to remain competitive, they must produce high quality tomatoes with unique and marketable characteristics. Following the decline in demand for regular tomatoes, two innovative products were developed: cherry tomatoes and cluster tomatoes, both of a very high quality, for export to European and USA markets. Other tomato products such as cluster cherry tomatoes and extra-sweet tomatoes grown in brackish water have also been developed, but on a smaller scale. Continuous research, the breeding of new varieties, as well as the development and implementation of innovative agro-technical methods, are a guarantee for continued production and supply of tomatoes for local consumption and export, and in the future will enable the growers to maintain their competitive status. INTRODUCTION1.
  • 6. 2. PLANT MORPHOLOGY Leaves: In most varieties, the leaves consist of two pairs of serrated leaflets and a terminal leaflet. Small secondary leaflets develop between the leaflets. The leaves of the tomato plant, like the stem, are covered with fine hairs. Inflorescence: Inflorescence appears on the main stem and lateral branches. The number of flowers per inflorescence is determined according to the varieties and growing conditions. Varieties with a small fruit (cherry tomatoes) have 50 and more flowers per inflorescence. Varieties with a regular-sized fruit usually have between 4 and 10 flowers per inflorescence in optimal conditions. However when flowering begins and temperatures are very high, there may be fewer flowers per inflorescence. On the other hand, when temperatures are low, there are more flowers per inflorescence. 2 Growth habits of tomato plants: Determinate growth: These tomato plants are relatively compact and grow to a certain height. They flower and set all their fruit within a short time. The main stem and lateral branches terminate in two consecutive inflorescences after a number of nodes, according to variety. In these varieties, the number of inflorescences per stem is not fixed. Determinate varieties can be grown in open fields, spread out over beds or trellised on sticks, if the varieties have a strong growth. Indeterminate growth: Indeterminate tomato plants grow continuously, producing flowers and fruit over a long period of time until the grower or weather conditions terminate the crop. The main stem and lateral branches continue to grow and the number of leaves between inflorescences is more or less fixed. In these varieties, the inflorescences appear with a set number of leaves between the inflorescences on the main stem and lateral branches. Indeterminate varieties can be grown on trellises in open fields and greenhouses, and the plant is shaped by pruning the lateral branches. Roots: Development of the tomato plant’s root system depends on the growing method, type of soil and irrigation regime. In soil-less culture, roots develop according to the size and shape of the growing container. The root system in light soil is not as deep as the root system in medium- heavy soil. Plants that are grown directly from seed develop a denser root system than plants that are propagated or prepared in a nursery. When unrestricted by disease or soil type, tomato roots can reach a depth of 1.5 to 2 meters. However, the active part of the root system is not as deep. Under high humidity conditions, adventitious roots may develop together with the natural root system, but these roots do not contribute to plant development. Stems: The growing shape, number and lengths of stems differ according to the varieties and growing methods. Sympodial growth in tomatoes is characterized by a main stem that terminates with inflorescence after the appearance of a certain number of leaves and nodes. A lateral branch grows from a lateral bud, and again a number of leaves, nodes and inflorescences develop, and so on. Table 1. Number of leaves below first inflorescence and number of leaves between inflorescences on the main stem DeterminateIndeterminate Below first inflorescence Between first & second inflorescence Third and more inflorescence 6-14 3-5 3 6-14 2-3 0-1-2 Temperature has a significant effect on the timing and position of the first and second inflorescence on the main stem in relation to the number of leaves. When the temperature is high, appearance of the first inflorescence tends to be delayed. There are many leaves below the first and the second inflorescence. When the temperature is low, the number of leaves below the first inflorescence decreases and there are only a few leaves on the main stem below the flowering.
  • 7. Fruit: Mature tomato fruits are mainly red. However some varieties have fruit of a different color: pink, orange and yellow. The fruit is succulent and its shape varies according to variety and can be: globe, flattened globe, deep globe, flat or ribbed. The size of the fruit also varies according to variety: fruit of cherry varieties weigh between 8 and 20 grams, and large fruit varieties weigh up to 250 grams. Hereditary factors usually directly influence the size and shape of the fruit. However growing conditions and position of inflorescence on the plant also influence the growth and weight of the fruit. The tomato fruit can be characterized according to the number of locules (carpels): round, small and medium- sized fruit usually have two or three locules while flat and large fruit have about ten to twelve locules. Descriptions of tomato fruit include fruit with green shoulders (U+), and fruit without green shoulders (uniform = U). The absence or presence of green shoulders is a genetic factor. Direct exposure to sunlight of a green shouldered fruit deepens the green color and can even turn it to yellow. The foliage cover is the most effective way to reduce this phenomenon. Tomato fruit is defined as a joint fruit with an abscission point on the peduncle. Most fresh market fruits are picked with the calyx. When the fruit pedicel has no abscission point it is defined as jointless. Joint varieties are used when growing processing tomatoes because the fruits separate easily from the calyx. On the other hand fruits of fresh market cluster tomatoes are often jointless but are attached more firmly to the clayx. Flower: The flower is usually composed of six green sepals, six yellow petals and six stamens. The pistil is composed of an ovary, a long style and a simple and slightly swollen stigma. The ovary has between 2 and 20 ovules, shaped according to variety, and it reflects the shape of the fruit that will develop. 3 Fruit with many locules Female parts of tomato flower Natural tomato flower Fruit with 3 locules
  • 8. Changes in the fruit during ripening stages After the fruit has reached the mature green stage, rapid changes start to occur in the fruits. The chlorophyll gradually disappears, and at the same time, other pigments are created in the fruit, especially lycopene and b carotene. The b carotene concentration reaches a maximum level in the initial ripening stages, while the lycopene level increases as ripening nears completion, and even later. The estimated time from the mature green stage to full ripening of the fruit (90%) is about ten days. There are no significant changes in vitamin C level and total soluble solids (TSS) during the ripening process, although in varieties with a smaller fruit, sugar continues to accumulate in the advanced ripening stages. Aroma and flavor compounds also increase during the ripening process. However in this process the fruit is less firm, and its tolerance to cracking and sunburn increases. A red fruit is less damaged by sun. However when a green fruit is suddenly exposed to sun, it is severely damaged and the damage is apparent when the fruit is still green and also when it turns red. The pH level also decreases gradually during the final ripening stages, due to the increase of citric and malic acids. Temperatures affect development of the tomato color: lycopene, which gives the tomato its red color, is not produced at temperatures over 30ºC. However production of ß carotene, which gives the tomato its yellow color, continues. Production of ß carotene stops in temperatures over 40ºC. The best color of tomato fruits is produced at optimum temperatures between 20-24ºC. Firmness and shelf life Firmness and shelf life are characteristics of high quality tomato varieties, which are required for long distance transport for both local and export markets. The most significant method for acquiring firmness and shelf life is by breeding and developing varieties with firmness. The great success in acquiring this characteristic has been reinforced by Israeli geneticists who successfully introduced ripening-inhibitor genes into new hybrids. Amongst the genes known to inhibit ripening are the RIN and the NOR genes. Varieties heterozygous to the RIN gene (+/RIN) usually have a shelf life that is 20 - 50% longer than regular varieties, and varieties heterozygous to the NOR gene (+/NOR) have a longer shelf life, exceeding regular varieties by 50 - 100%. It is important to remember that fruit from varieties that have the NOR gene should be picked when pink or even more mature. Fruit picked before this stage will not develop the proper red color and the quality of the taste will be lowered. Flavor The flavor of tomatoes is influenced by the compounds of the fruit and the ratio between them. The tomato fruit is mostly water, with solids constituting only 5-7% of the fruit. About 50% of the solids are sugars (mainly fructose and glucose), and about 12% are organic acids (malic and citric acids). The tomato fruit includes other compounds in small quantities, such as minerals (K, Ca, Mg, P), proteins, pectic substances, pigments, amino acids, volatiles, vitamins, ascorbic acids and polyphenols. All these compounds affect the flavor and aroma of the tomatoes. In general, aroma and taste can be influenced by breeding/genetics.Agrotechnical activities also significantly influence improved taste. 7 Changes graph 4 Development of ripening Green mature
  • 9. 3 Temperature has a significant influence on the tomato plant’s fertility and directly affects both yield and product quality. There are extreme disorders in the tomato plant’s fertility in winter, when day and night temperatures are low - below 18ºC and 10ºC respectively - and in summer, when the day and night temperatures are high - above 32ºC and 22ºC respectively. The morphological and physiological changes in the tomato plant, which are affected by temperature, are described here: Temperature Temperature is the main climatic factor which influences most of the tomato plant’s development stages. The optimal temperature for growing tomatoes is between 22ºC and 26ºC during the day, and between 14ºC and 17ºC at night. Extreme temperature fluctuations may damage the tomato in the different growing stages. 5 CLIMATIC FACTORS AND THEIR INFLUENCE ON TOMATOES Table 2a. The tomato plant’s temperature requirements in the different growing stages Exposure to high temperature: Reduction of pollen viability and quantity in the flowers Reduction of number of flowers in inflorescence Appearance of poor and weak inflorescences Distortion of the anthers Elongation of the style beyond the anther Asymmetry in the inflorescence shape Delay in appearance of first inflorescence on the main stem Morphological changes - elongation of the plant’s internodes Minimum (ºC) Germination Growth Fruit set at night Fruit set in the day Production of red pigment - lycopene Production of yellow pigment - ß carotene Chilling injury Frost (freezing) Storage of pink and red fruit Growing stage Optimum (ºC) 11 18 10 18 10 10 16-29 21-24 14-17 23-26 20-24 21-23 6 for some hours (-2)-(-1) 10-12 34 32 22 32 30 40 Maximum (ºC) Elongation of the style beyond the anthers Asymmetry in inflorescenceFew flowers in inflorescence Effect of high temperature
  • 10. Radiation and daylight Increased radiation intensity stimulates vegetative growth and results in higher yields, mainly due to increased assimilation and production of dry matter. In many plants, the growth rate in the dry weight per area unit is influenced Continuous exposure to low temperature: Reduction of pollen viability and quantity Distortion of ovary and increased incidence of fruit deformation Elongation of the ovary Distortion of the stamen Increased number of flowers in inflorescence Short internodes and compact plants Relative humidity Relative humidity of 65% to 85% is beneficial to the development of the tomato plant. This is expressed in optimal growth and fertility. Higher relative humidity results in irregular release of pollen grains from the anthers and unsatisfactory distribution on the stigma. High relative humidity also creates conditions for development of various leaf diseases, such as late blight, caused by Phytophthora infestans, Botrytis, and Erwinia. Incidence of blotchy ripening increases in high humidity. On the other hand, in relative low humidity, there may be low fertility as the pollen grains dry out on the stigma even 6 The data in the table clearly indicate the damage to the fruit and fruit quality caused by excessive shading, which results in insufficient radiation. by radiation, more than by any other environmental factor. A positive correlation was found between this rate and radiation intensity. When examining the assimilation rate of tomato plants, it was found that the lowest assimilation rate was recorded at low radiation intensity in December (Israel), approaching the shortest day of the year, while the maximum assimilation rate was recorded at high radiation intensity in summer. In winter, the photosynthetic radiation quantity is the principal factor that determines growth rate, while in summer, the radiation intensity is usually sufficient, and growth may be restricted by other factors. Tomato plants are usually indifferent to daylight hours and photoperiod, however when the radiation intensity is low, there is a negative influence on the plants and on the yield components, as a result of lack of radiation in greenhouses during the winter months. The yield and its quality are severely damaged by artificial shading or excessive accumulation of dust on the external covering sheets, which reduce the quantity and intensity of the radiation penetrating into the greenhouses. In an experiment conducted in the Besor experimental station in Israel’s southern desert, a significant reduction in the number of fruit in inflorescence and ripening percentage was found with 12, 34 and 55 % shading of light intensity (according to A. Sagie). Shading was also found to have a negative influence on the percentage of hollow (puffy) and blotchy fruit. Table 2b. Influence of shading on fertility and ripening of tomatoes in the Besor experimental station Percentage of undeveloped fruit set Shading percentage Fruit in inflorescence Number of flowers in inflorescence Number of flowers in inflorescence 12 34 55 10.0 10.4 9.0 7.1 6.7 5.6 71.0 66.0 63.0 29.0 32.0 41.0 Elongated fruit (Lemon shape) – low temperature Short internodes, distortion and cracks in stem - low temperature Deformations with cat face – low temperature
  • 11. 4 GREENHOUSES FOR TOMATO PRODUCTION Growing tomatoes in greenhouses is a means to isolate plants from the environment, allowing growing conditions that are suitable for development of the plant and production of a high quality and quantity yield. In greenhouse production, tomato plants are grown on a single stem or two stems per plant, according to the variety and season. In this method, the plants grow vertically on strings or trellises and are arranged in single or double rows on the beds. In order to achieve a maximum yield, technologies should be adapted to the growing conditions. Some important considerations are the shape and position of the structure, covering material, insect-proof nets, heating and cooling methods and a large range of accessories. These technologies enable production under optimum conditions, or improved conditions. When planning the greenhouse, the distance between the greenhouse units should be considered, so as to allow efficient ventilation for the regulation of temperature and humidity. Additional things to consider are how to optimize the workers’ time when moving among the structures and the convenience entailed when performing agro-technical tasks, such as cultivation, harvest and spraying. The greenhouse design should facilitate transportation of the produce from the greenhouse to the packing house. Advantages of greenhouse production 1. Protection from harsh climatic conditions Rain and hail Low temperature Winds and Storms Dew and excess humidity 2. Control over climatic factors Heating Cooling Shading CO2 enrichment 3. Adaptation of production and marketing to local and export market requirements Production during different growing seasons Production and marketing over an extended period Continuous supply 4. Savings in production costs Increased yield per unit Increased efficiency of agricultural inputs 7 Convenient operation 5. Decreased use of pesticides Use of nets and films to keep out insects 6. Improved product quality Use of quality varieties Uniform fruit shape, color and size Use of varieties with a long shelf life Characteristics 1. Agreenhouse for growing tomatoes should be designed to hold a vertical load of 35 kg/m2. 2. The greenhouse should be planned and approved by an authorized engineer. 3. The building materials should be durable: concrete, galvanized steel, wood treated by impregnation, welding after galvanization coated with zinc-rich paint. The screws should be galvanized and vibration-resistant 4. The gutter direction should be north-south, to allow maximum penetration of light and minimum shade on the plants throughout the day. 5. If the greenhouse does not have roof vents, its length (gutters) should be limited to 36 - 40 m. The width, which is composed of the gable spans, is unlimited. 6. If the greenhouse has roof vents, its length and width is not limited. 7. The gutter height required for producing tomatoes on trellises over a long yielding period is at least 4 m. 8. There should be a distance of 10 to 12 m, or at least the equivalent of twice the structure height, between nearby greenhouses. 9. The greenhouse should be able to withstand winds of 150 km/h, and it should have a life span of at least ten years. 10. It is recommended to install porches around the greenhouse to reinforce its resistance to strong winds. 11. The greenhouse should be constructed on a 0.5%-1% linear and lateral slope, for efficient drainage of rain and in soilless culture for the surplus irrigation water. 12. There should be accessible approaches to and from the greenhouse for passage of agricultural equipment and convenient transport and removal of fruit. Notes: A. These principles are suitable for the conditions in Israel and for countries with a similar climate. There are other greenhouse models which are compatible with local conditions, such as in Almeria, Spain. B. The above information relates only to polyhouses. Essential accessories 1. Roll-up curtains on each wall. The curtains on the long side should be divided into two or more sections. 2. Double entrances for convenient movement of produce. 3. Preparation for connection of an insect-proof net by installing horizontal beams on the wall at a suitable height. It is recommended to install insect-proof nets at all openings to ensure complete sealing of the greenhouse. before germination. This results in partially fertilized, small, deformed and hollow (puffy) fruit. At relatively low humidity and high temperature, there is a high and rapid evaporation rate of water from the leaves. In these conditions, the root system cannot supply the water volume required for evaporation via the leaves, and in extreme cases, this may lead to partial wilting of the plant growing tip and increase of blossom end rot, which stems from a shortage of calcium (Ca) in the fruit tissue. It was found that excessive humidity in the greenhouses may reduce evaporation from the leaves, inducing root pressure on the fruit. This increases incidence of fruit cracking.
  • 12. Span width Greenhouses have different span widths. The type of covering greatly influences the span width when planning the greenhouse. For example, when a rigid covering is used, greenhouses can have a span width of 9 or even 12 meters. In this case, there will be fewer gutters per hectare, and there will, of course, be less shading on the plants. When a flexible covering such as plastic polyethylene sheets is used, the greenhouse should have a span width of 6 to 8 m. Plastic coverings are sensitive to climatic conditions and are susceptible to tearing. For example, in very hot weather, the sheets become too slack and their grip on the frame is reduced. The sheets may also be damaged and tear during storms. An important consideration is that damage to the sheets may be partial, and they may be easily repaired or replaced at a relatively low cost. When the covering is flexible, the spans are narrower and therefore more gutters are required, so there is more shading compared to a wide- span greenhouse. 4. Climate control equipment. The greenhouse should be prepared for installation of climate-control equipment, such as heating and air circulation fans, equipment for applying pesticides and a thermal screen. The position of the heater should be determined in advance to enable convenient access for ongoing maintenance and refueling. 5. Vertical beams should be installed on the greenhouse walls, perpendicular to the crop rows. A crop wire runs from wall to wall. Long greenhouses with a path in the middle should have support poles in the center, and the crop wire should be divided into two. 6. The crop wires that are parallel to the crop rows are made of soft galvanized steel, and have a diameter of 3 - 3.5 mm. The wires should be stretched between the two beams at either end of the greenhouse. 7. An infrastructure for soilless culture, recycling of drainage water and collection of rainwater. 8 Greenhouse roofs There are many types of greenhouses on the market, with different span widths and roof models. Some structures have an even-span roof, which is especially suitable for rigid covering, such as glass or polycarbonate. Structures with a gable or arch roof are mainly suitable for plastic (flexible) coverings. A flexible covering on an arch roof enables the covering to be firmly attached and properly stretched, to prevent fluttering. This saves the investment in a ridged or fixed roof such as glass. Arigid polycarbonate covering is flexible in a certain direction and it can be placed on curved roofs. Choice of roof shape will be adapted to the type of future covering and cost of covering material. In Israel and the Mediterranean Basin, polyethylene plastic films are usually used. Rigid coverings are not common in Mediterranean countries, for the following reasons: High cost of construction The greenhouse frame, especially the roof, would need to be adapted to rigid covering material Radiation transmission through these materials (not glass) could be reduced, as a result of reduced transparency after a few years. Diagram of greenhouse Types of roofs
  • 13. 9 Roof and side ventilation protected by net Roof ventilation protected by netSide ventilation protected by net Roof vents Roof, gutter or ridge vents are vents which open along the length of the span. The hot air, which accumulates in the greenhouse, rises and is trapped in the upper part of the greenhouse (in the triangles), where it has a great influence on the heat load in the greenhouse. A vent opening in the greenhouse roof releases this heat and greatly reduces the heat load. Release of heat through a roof vent in greenhouses with rigid coverings, such as glass, has been applied for many years in Israel and other countries. However, in greenhouses with plastic coverings in Israel, installation of a vent along the span is not an option, due to the labor required every year to seal the greenhouse for heating and to keep out insects, which serve as vectors for viruses. Developments in the greenhouse industry, the many manufacturers and the competition between them, have led to the development of new greenhouse models with roof vents which are also suitable for plastic coverings. It is important to install insect-proof nets in the roof vents. All roof vent models can be opened manually or by a computer-controlled motor. Roof vents
  • 14. 5 Net houses for tomato production provide growing conditions that are similar to those in greenhouses, with a relatively low investment. Growing in net houses should begin and terminate in seasons when the climatic conditions permit it. Therefore, growing should be planned so that most of the yield is harvested before temperatures drop and the rainy season begins. If even the lightest rain penetrates the nets and wets the plants, the fruit will crack, its quality will drop and in addition, the prevalence of leaf disease will increase, especially early blight (Alternaria solani), late blight (Phytophthora infestans) and leaf mold (Fulvia fulva). In the Israeli and Mediterranean climate, tomatoes are planted in net houses in the spring or early summer. In the rainy season and when humidity is high, the plants may be severely damaged. The net house should be completely covered with insect- proof net (50 mesh), to protect against invasion of insects and the following specifications should be strictly adhered to. NET HOUSES FOR TOMATO PRODUCTION Specifications 1. Net house height: 3.5-4.0 m 2. Recommended unit size: 1 ha 3. Suitable for simultaneous hanging of two nets: 50 mesh covering and internal shading screen, according to need 4. Crop wires attached to structure 5. Spaces between poles: 4x4m or 4x6 m 10 6. Double entrance, recommended in the center of the net house, to allow passage of a tractor for cultivation and preparation of soil, loading produce and other agro-technical activities. 7. The net is tied to the structure with 6-8 m straps, and buried in the ground around the frame. 8. The poles are anchored in the ground. 9. The section of the net that is anchored in the soil and the lower part of each pole are treated with tar up to 20 cm above ground level. 10.The pole tops are protected with plastic to prevent friction and tearing of the net. 11. Materials: 2.2 mm thick, hot-dipped galvanized poles 12.Steel cables to withstand 120 km/h winds 13. A gable structure with gutters is preferable to a flat one. 14. Anchors around the structure are according to the manufacturer’s specifications, examined and approved by an authorized party. 15.It is recommended to purchase the structure from an authorized manufacturer. Greenhouse covering films isolate the plant from the external environment, and its properties influence its relationship with the environment. The most common coverings are made of plastic materials. Most of the flexible films used to cover greenhouses are made of polyethylene (PE). PE has many advantages, including: light weight, relatively low cost, flexibility, transparency, easy handling and ability to withstand diverse climatic conditions. The properties which are required by films for covering greenhouses in general and greenhouses for tomato production in particular, can be divided into two main categories: mechanical properties, and optical and thermal properties. PE covering films with a thickness of about 120 micron are usually used for one year. Thicker films are used for more than one year. Mechanical properties The mechanical properties are defined in Israeli Standard 821, and relate to sheet strength, tensility (ability to endure stress), durability, parameters related to dimensions (length, width, thickness, density), and permitted deviation rate. UV stabilizer is the main additive in sheets, and is most important in determining mechanical properties. This additive provides the sheet with durability and resistance to radiation ageing and prevents its degradation. Optical properties Optical properties have a decisive influence on the yield level, fruit quality and energy balance in the greenhouse and the behavior of pests and diseases. Net house with gable roof Net house with flat roof 6 GREENHOUSE COVERING FILMS
  • 15. 11 Diagram of net house - gable and flat roof
  • 16. Optical properties can be classified according to their influence on the different radiation fields: 1. Thermicity: IR additive enables sheets to absorb or reflect infrared radiation in the range of 7 to 15 microns (IR 7-15), retaining the heat that accumulated during the day (energy). 2. Visible light (400-700 nm): maximum light transmission is required for proper plant development and optimum photosynthetic efficiency. 3. Light diffusion: This is important in greenhouse tomato production, where there is a high degree of shading among the plants. High radiation diffusion helps to increase photosynthetic efficiency in the shaded parts of the plants in greenhouses. Special additives Certain additives in the film coverings have a positive influence on the plants due to secondary effects. These include the following additives: 1. UV absorption: UV absorption or UV blocking additives reduce pest damage and prevent spread of viral disease in tomato plants, as insects become disorientated in a UV-free environment. 2. Anti-drip: This additive prevents condensation in a form of droplets on the sheets and consequent dripping on the plants, reducing incidence of diseases which develop in moist conditions. Light transmission is also more efficient when there is no condensation on the films. 3. Anti-dust: This innovative and unique additive prevents accumulation of dust on the outside layer of the film, so that radiation penetrating into the greenhouse is not reduced. This saves the labor which is required to wash the accumulated dust off the covering. 4. EVA (ethylene vinyl acetate): EVA improves the film’s mechanical and optical properties, as well as its heat retention capacity. Protecting the film covering As well as the additives that are designed to reinforce the films, it is recommended to apply white acrylic paint to the outside of the film’s contact points with the frame. This prevents degradation when the metal frame overheats. The upper side of the metal arch can also be painted white before construction of the greenhouse. White plastic tape adhered to the metal also prevents heating of the metal and decrease wear of the film at the contact points with the frame. Insect-proof nets Insect-proof nets in greenhouses for tomato production are defined as 50 mesh screens (50 openings per inch), and are designated to prevent infiltration of tobacco whitefly (Bemisia tabaci) - a vector for tomato yellow leaf curl virus (TYLCV) – and other insects. These screens, which were developed in Israel, contribute greatly to reduced use of pesticides, as they physically block passage of insects into the greenhouses. Reduced pesticide application enables the use of bumblebees for pollination of tomato flowers in greenhouses and net houses. The 50 mesh screens were approved for use after having been determined as impenetrable by tobacco whitefly, and from the aspect of their mechanical properties and resistance to air passage at different pressures. The screens are made of interwoven 22-24 micron threads Soil preparation Most soil types are suitable for tomato production, except for heavy limestone and poorly drained soils. However, in order to produce a high-quality fruit, it is recommended to grow tomatoes on light or medium sandy soil. In regions where the soil is heavy, claylike and impervious, it is recommended to grow tomatoes in soilless culture. For further details, see section on Soilless Culture. Well-crumbled growing soil, which is level and smooth, is important for proper planting and uniform depth. Uniform and rapid establishment of the plants greatly depends on the quality of soil cultivation which is completed before soil sterilization and planting. The soil is cultivated to a depth of at least 35-40 cm. A shovel plow enables cultivation close to the greenhouse poles, and does not leave uncultivated rows or open furrows in the middle of the spans. In medium and heavy soils, it is recommended to cultivate deeply once every two years, using a vibrating plow, which penetrates 60-70 cm into the ground. The plowing is needed to open up soils which became sealed and compact due to the continuous growth especially the walking area. This deep plowing improves aeration of the soil and drainage of surplus water, prevents accumulation of salts and improves soil sterilization treatments. After initial cultivation, fertilizers are applied and the soil is irrigated with a sprinkler system. After 5-8 days, the ground is cultivated to crumble the earth clods and to continue preparing the soil for sterilization. There is no need to build raised beds for tomato production in greenhouses and net houses. It is sufficient to determine and mark the paths between the rows and to avoid walking on the growing area. 12 and are UV stabilized against radiation damage, which provides them with durability. BioNet© screens have recently been introduced to the market. This is a 50 mesh screen with UV absorption properties, which significantly reduces insect damage and prevents incidence of viral diseases, especially TYLCV, in tomatoes. Painting arches white 7 PREPARATION FOR NEW CROP
  • 17. Soil mulching Soil mulching with polyethylene sheets is quite common in the different growing methods, both when growing in soil, as well as in soilless culture in containers. Mulching is an agro-technical activity designed for different objectives, which are influenced by the sheet properties: Mulching with transparent sheets results in heating of the upper soil layers and encourages growth, especially when planting is in low temperatures. Mulching with black, silver, or black and white PE is suitable for autumn and spring and prevents germination of weeds. Co-extruded mulching, which is black on the bottom and white on the top, or one white layer contributes to increasing radiation by reflection to the plants. This is suitable for northern countries where there is little radiation in the winter. In general, mulching creates a climate that is suitable for growing. When the soil is covered with PE, it has been found that irrigation efficiency increases and the root system is more active. Conditions for development of leaf diseases have also been found to decrease, following improved microclimate in the greenhouse space by reducing humidity. Mulching is applied over the entire span or in strips over the beds. With PE mulching, the growers’ awareness of sanitation increases, and leaves, stems and fruit are easily removed from between the rows. The recommended thickness of plastic used for soil mulching is 40-50 micron. The diameter of the holes in the plastic should be 8-12 cm. Soil mulching in high temperatures, especially in the hot summer, increases the temperature under the plastic and creates negative and poor conditions for rooting and establishment of the young plants. In high temperatures, it is recommended to prepare large holes in the mulching sheets,in order to release the hot air and avoid heating of the soil. Soil sterilization Tomatoes in greenhouses are susceptible to various diseases, especially soil-borne diseases. These pathogens can survive in the soil from one season to the next and moreover, these inoculates (infecting material) can multiply in the soil to extreme values. As soon as tomatoes, or any other host plant which is sensitive to these diseases, are planted, they may be damaged by one or more pathogens. Tomato production, which is considered to be expensive, continues over a number of months and there is no crop rotation in the greenhouses. Therefore, great effort is invested to reduce the establishment of pathogens in soils or growing medium in greenhouses, by performing some form of sterilization as well as by sanitation treatments during and at the end of the season. Here are the main soil-borne pests that may cause damage to the new tomato crop: 13 Fungal diseases: fusarium wilt and verticillium wilt - most commercial varieties are resistant to these diseases, however part of them are resistant to nematodes and to crown root rot (Fusarium oxysporum f.sp. radicis- lycopersici); but there is no resistance available for stem rot (Sclerotinia sclerotiorum), Southern blight (Sclerotium rolfsii) or Corky root (Pyrenochaeta lycopersici). Since the genetic sources for resistance to these diseases are limited, they must be controlled by soil sterilization. Bacterial diseases: bacterial canker (Clavibacter corynebacterium michiganensis); bacterial wilt (Pseudomonas corrugate); soft rot (Erwinia carotovora); and southern bacterial wilt (Pseudomonas solanacearum) Viral diseases: mainly tobacco mosaic virus (TMV). Most varieties are resistant to this disease, except for some cherry varieties. Pests: root knot nematode (Meloidogyne spp.), various soil-borne or airborne pests, some of which are vectors for viral diseases, such as western flower thrips (Frankliniella occidentalis) Parasitic weeds: field dodder (Cuscuta campestris) and broomrape (Orobanche spp). These weeds are established in the soil, propagate by seed and germinate with a suitable host. Tomato plants are hosts for these parasites, and are severely damaged when attacked. Noxious weeds: many types of weeds may reproduce and germinate in tomato production greenhouses, if there is no suitable soil sterilization. Soil sterilization methods 1. Methyl bromide: This is suitable for control of most pathogens and noxious weeds in the soil and growing medium, except for viruses and bacteria. Use of methyl bromide is being phased out according to international pacts (the Montreal Protocol). 2. Solarization (sun/solar sterilization): Satisfactory results have been received with soil solarization in soilless culture. This method is effective in the hot season.The efficiency of solarization is limited in soils. 3. Metham Sodium: This material is sufficient for control of various soil fungi and partial control of weeds. It is very effective in soilless culture for most pathogens. 4. Telodrip inline (Telon with chloropicrin). This multipurpose liquid fumigant is applied through the drip irrigation system and covered with PE film. It is used to control nematodes, fungal soilborne diseases and certain weeds. 5. Steaming: This method is suitable for control of most pathogens, including viruses and bacteria. It is suitable for disinfestations of soilless culture, but is not suitable for all soils, especially heavy soils. 6. Formalin: This material is suitable for sterilization of soil or growing media which have been infested by bacteria. 7. Use of specific pesticides for control of soilborne pests, as well as specific fungicides, nematicides, and herbicides.
  • 18. Since innovative sterilization treatments are restricted to a limited amount of pathogens, it is recommended to combine a number of sterilization methods according to need. A combination of methods will ensure better results than any separate treatment. Beside the chemical and the physical treatments for soil sterilization it is recommended to exploit the genetic factor to reduce damages of soil-born diseases by introducing the resistance varieties or the use of rootstock in combination with grafting Details regarding preparation of soil and sterilization methods can be found in the manual “Recommendations for Control of Pests in Vegetables”, published in Hebrew by the Agricultural Extension Service of the Ministry of Agriculture and Rural Development, Israel. Sterilizing the greenhouse space Greenhouses can be sterilized in the summer. After a crop has been removed from a greenhouse, the greenhouse should be sanitized by solar radiation (solarization) by sealing it hermetically for three to four weeks. Temperatures in a greenhouse which is sealed in the summer months reach values which destroy most pathogens in the space and on the frame of the greenhouse. In order to increase the sensitivity of pathogens to high temperature, it is recommended to wet the greenhouse interior and soil once a week by using a 5-10m3/h micro-sprinkler system. The greenhouse and soil should be wetted at night or in the early morning, when temperatures are mild, to prevent bursts in the irrigation system. Accessories and equipment that are sensitive to high temperatures and which may be damaged by the heat should be removed before sealing the greenhouse. The greenhouse is sterilized as part of a comprehensive method and a means for sanitation before planting a new crop. Preparing the greenhouse Before planting, the greenhouse is prepared, covered and protected against tobacco whitefly, which are vectors for tomato yellow leaf curl virus (TYLCV). Covering all the sidewalls with a net keeps these insects out of the greenhouse. The greenhouse should be hermetically sealed, especially in the gutter area, to provide maximum protection against invasion of the pest. A double door should be installed at the entrance of each greenhouse, to create a separating passage between the greenhouse and the environment. The greenhouse film covering should be thermal IR PE film, with anti-drip additives, both on the roof as well as on the sidewalls (curtains). The films should have a thickness of at least 0.12 mm (120 micron). In many cases, the effectiveness of the additive, which is designed to prevent condensation on the films, lessens in the second season, and therefore it is not recommended to use the material for more than one year. 14 Covering the soil before sterilization with methyl bromide and other chemicals Covering beds – soil solarization Covering the substrate containers – soil solarization
  • 19. 8 In order to reduce the heat load in the greenhouses in the early season (summer-autumn), various methods can be applied to improve the climate conditions in the greenhouses, until a vegetative mass is created which is able to regulate the greenhouse temperatures by evaporation (self-cooling by the plants). These methods include: 1. Evaporative cooling (adiabatic cooling) The principle of evaporative cooling is based on water evaporation. In this process, the pressure of water vapor in the air increases and the air temperature in the greenhouse drops. In other words, the sensible heat is transformed into latent heat by capturing the heat in the water vapor. There are a number of methods for increasing humidity Double entry in greenhouse Double entry in net house IMPROVING CLIMATE CONDITIONS IN SUMMER AND AUTUMN in the greenhouse atmosphere, in addition to humidity resulting from water that evaporates from the plants in the transpiration process. In recent years, misting and fogging methods have been developed, joining the wet pad and fan cooling method. The misting and fogging systems are differentiated by droplet size. The droplet size has a significant effect on the process of heat replacement in the air and the degree that foliage is wetted. When the droplets are smaller, cooling is more effective and the leaves are not wetted. In a system with smaller droplets, the quality of water used for cooling is important, and this should be taken into account when planning the cooling system. a. Cooling by misting: A misting system for cooling plants is composed of a system of water lines with low-volume mini-sprinklers (100- 250 droplet size), which have anti-drainage valves. The system is usually installed at the height of the crop wire and below the gutter. The mini-sprinklers should be close enough to each other to wet the entire floor area, without overlapping. The misting system should operate for 0.5- 1.0 minutes, every 15-20 minutes during the hot and dry hours. If the system has no control or sensors, operation frequency and time should be based on the farmer’s experience. The misting system is switched on and off by an automatic timer and electric valves. The water wets the foliage, and cools down the leaves when drying out. This system is effective on hot, dry days, and is suitable for use with high quality water. Water with a high concentration of chlorine and sodium may burn and damage the plants. This cooling method is designed to reduce leaf and plant temperatures. The misting system has a marginal effect only on reducing air temperature. b. Cooling by pad and fan: This cooling method, which is common in many greenhouses, has a wet pad on one wall in the greenhouse, with fans on the opposite wall. The fans expel the air from the greenhouse, and as a result of the sub-pressure that is created in the greenhouse, air is drawn from the wet pad on the wall opposite the fans. The cooling pad is composed of a special carton block with narrow air passages over its entire surface. The carton block is wetted with a large volume of water using a pump system, which pumps water in a closed cycle. The air, which is drawn into the greenhouse, passes through the wet pad and absorbs the water vapor. This increases the humidity in the air and lowers the greenhouse temperature. The disadvantages of this system is that it are very expensive, the humidity and temperature in the greenhouse are not uniform, drainage of brackish water is required to prevent clogging in the wet pad, and the plants are at risk if there is a power failure, because the system will not operated especially in hot summer days, when the greenhouse is closed.The efficiency of the system depends on the relative humidity outside and the air exchange in and out of the greenhouse. 15
  • 20. c. Fogging: This system is based on air vents in the roof, fans on all sides of the greenhouses and nozzles which are installed uniformly around the greenhouse. Water droplets (5 – 25 micron) in the form of fog evaporate before reaching the plant. The air, which enters through the roof vents, carries the fine water droplets and the water evaporates with the air flow. Water evaporation in the air cools the air in the greenhouses and lowers the temperature. The advantage of this system is uniform cooling of the entire greenhouse, which enables construction of greenhouses which are larger than conventional. In this system, evaporation leaves small grains of salt which were in the water. These particles may float and move out of the greenhouse with the air flow, however some may sink onto the plants and deposit salt on the foliage. Care should be taken to prevent this by using water with a good quality or water which has been treated before use in the fogging system. 2. Temperature reduction by shading - reducing solar radiation intensity that penetrates into the greenhouse a. Whitewashing roofs: This is the most conventional technical solution for reducing solar radiation penetrating into the greenhouse, thereby reducing heat load in the greenhouse. The exterior covering is sprayed with suitable whitewashing material. It is recommended to avoid using plaster, which corrodes the metal and damages the film covering. 16 Diagram of a cooling pad and fan system Wet pad Fans
  • 21. When the white coating is new, it reflects some of the radiation back to the sky, reducing the radiation that penetrates into the greenhouse, and lowering the temperature. If the whitewash is sprayed on the roof in the spring, when the films are dusty, the color achieved will be brown, and not white. This color usually absorbs the radiation and generates heat, while producing excess shading. This combination of lack of radiation and increased temperature damages the plant, and therefore it is important to clean the films before applying whitewash. b. Shade nets: The radiation intensity and temperature inside the greenhouse can be reduced by covering the structure with a knitted or woven black shade net. The net is installed above the gables, without being too close to the film covering. The radiation should not be reduced by more than 20 to 25% of the radiation intensity under a transparent covering. Shading with this method reduces the transmission of radiation into the greenhouse, and prevents a drastic rise in temperature inside the greenhouses. c. Moveable reflective screens: A reflective thermal screen, which is spread out during the hot hours of the day, is another method used to reduce radiation penetrating into the greenhouse. When the screen is completely spread out, it reduces the radiation intensity that penetrates into the greenhouse and lowers the temperature. The screen is spread out and closed by a system of twines installed above the crop wire and below the gutters, and operated by a system of motors that operate according to thermostats or radiation sensors. This screen is also used to retain heat and save fuel costs, when it is spread out at night in the winter. It reduces heat loss in the greenhouse by blocking escape of infrared radiation (IR). Whitewashing roofs to reduce solar radiation intensity 17 Shading with shade nets Moveable reflective screen Accumulation of dust on greenhouse and net house coverings Covering materials accumulate a great amount of dust, due to the static electricity on the covering surface, which attracts dust particles. Dust accumulation reduces light transmission into the greenhouse or net house, which damages the yield quantity and quality. Dust starts to accumulate on the covering material immediately after it has been spread out. More dust accumulates in bad weather and when heavy mechanical equipment operates inside and outside the greenhouses. Tests show that cleaning the covering films or nets leads to improved light transmission, resulting in higher yields and improved quality. Cleen insect - proof net Accumulation of dust - low radiation and limit of ventilation
  • 22. 9 18 The nets should be cleaned to increase light transmission and air movement, which improves ventilation inside the greenhouses. The covering films should be cleaned to improve light transmission into the greenhouses as well. Cleaning screens to improve ventilation Insect-proof nets, which are installed on the greenhouse walls and roof vents, accumulate a lot of dust, which adheres to the screen threads and blocks the holes through which the air enters the greenhouse. In order to improve and increase air passage and ventilation through the screens, it is important to remove accumulated dust whenever the screens become clogged. The screens can be washed by spraying water on them from the inside of the greenhouse outwards, and from top to bottom. A high-volume sprayer connected to a suitable spraying gun, or a hosepipe with a regulated outlet attached to a tap, can be used for this purpose, since a high-volume water spray may damage the screen. Cleaning film covering In the autumn, when the days become shorter and clouds begin to gather, dust and lime which is used for shading, should be removed from the film covering in order to increase the radiation that penetrates into the greenhouse. Postponing this treatment damages the yield quality and quantity. The film covering should be cleaned again during the winter in order to ensure that they are transparent, to allow maximum penetration of radiation into the greenhouse. The film covering can be washed with water and a brush for mechanical separation of dust from the film. Cleaning the roofs and coverings increases the photosynthesis process, resulting in higher yields and improved quality. Most greenhouse tomato production is dependent upon hybrid varieties. These seeds are developed by breeding specialists and sold by commercial companies. The advantages of hybrid seeds are that they have very high vigor, good uniformity, high production and quality. Disease resistances are also bred into these varieties. Growers should only purchase seeds that have been produced by reputable companies and are properly packaged in sealed packages. Labeling should include information about the variety and proper seed storage. The production of a seedling, frequently referred to as a transplant, is an extremely important procedure, as future plant, growth and fruit production is affected by the character of the seedling that is produced. Today, most tomatoes for fresh marketing are grown in plugs and rooted in a growing medium, which is usually organic, such as peat, or vermiculite. A good plant is disease- and pest-free, and has three to five developed leaves. It has a well-developed root system, with a strong hold in the growing medium in the tray cell, so that when SEEDS, SEEDLING PREPARATION AND TRANSPLANTING these seedlings are removed from the tray in the nursery and brought to the field for transplanting, the growing medium remains around the roots. Seedlings that are 3-5 weeks old are considered to be ideal, while seedlings over 5 weeks old are less desirable. Trays with 1.25” to 1.5” cells are used to produce quality tomato seedlings. The seedlings are produced in commercial nurseries that specialize in seedling production. The farmer orders seedlings for planting in advance. Generally, 25 to 50 days are required from sowing until supply, depending on the season and climatic conditions. The seedlings should be planted within 24 hours after removal from the nursery. Early transplanting provides better conditions for the plants and the future field. Seedlings received from commercial nurseries are packed in cartons and kept in a shaded area that is protected from insects until they are planted. Tomato plugs are planted in damp soil that has been irrigated in advance. The seedling’s roots (the plug) should be straight, and not folded when planted in the ground, and covered completely by soil. Air pockets are removed by pressing the soil around the roots with hands or a trowel. The seedlings should be irrigated lightly within one to two hours after planting. A quality seedling and proper planting guarantee establishment of the seedling in its new environment, and ensure that growing is not delayed. If seedlings are planted on a hot day, the plugs should be dipped in water before planting. Uniform seedlings produced in a commercial nursery A seedling that is suitable for planting
  • 23. Plant spacing and density – common tomatoes Tomato plants in greenhouses are grown in double rows, which enable optimal growing, radiation and ventilation conditions, with wide passages between rows for easy access by workers. A distance of 170-185 cm between the double-row centers is required, and the span width should be adapted accordingly. Greenhouses that are marketed in Israel do not have a uniform span width, and the span width is adapted to the number of double rows. The distance between seedlings in the rows is determined accordingly, and should not be less than 40 cm. A high yield is achieved with about 20,000-25,000 plants per hectare. More plants per hectare will not increase the production. The fruit will be small and puffy with a poor color, and there will be a higher incidence of disease in the dense conditions. Table4.Recommendationsforrowspacing in greenhouses with varying span width Estimated density per ha. Plant spacing Span width Double rows per span 50 cm 40 cm 50 cm 45 cm 50 cm 50 cm 50 cm 40 cm 40 cm 45 cm 22,000 25,000 20,000 23,500 21,000 25,000 22,000 23,000 25,000 22,000 5 4 4 4 4 4 3.5 3 3 3 9 m 8 m 8 m 7.5 m 7.5 m 6.4 m 6.4 m 6.4 m 6 m 6 m Transplanting young plants in double rows 19 In order to increase the radiation that penetrates between the crop rows and vertical growth, distance between double rows should be 50-60 cm at the plant base. This distance can be maintained by fixing the horizontal crop wires at the same distance or even slightly wider, on the internal greenhouse frame. The best position for the double crop rows is one row on either side of the gutter poles and the other rows are formed along the span width. This positioning is convenient for agro-technical activities. The following diagram illustrates distribution of crop rows in greenhouses with span widths of 7.5, 8.0 and 9.0 m. Row spacing in different greenhouses and span widths Enough space between the double rows allows light penetration 9.0 m 9.0 m 9.0 m 9.0 m 7.5 m 7.5 m 7.5 m7.5 m 8 m 8 m 8 m 8 m Greenhouse with 9.0 m spans Greenhouse with 8.0 m spans Greenhouse with 7.5 m spans
  • 24. Tomato plants that are grown in greenhouses are shaped into one or two main stems by pruning all the sideshoots (suckers) that develop in the leaf buds on the main stem. The height of the crop wires in the greenhouse is planned according to the duration of the harvest season. 1. When the harvest season is limited to 3-4 months, the crop wires should be 2.2-2.5 m high, so that they can be reached by the workers. When the plant tops reach the crop wire, they are bent in one direction and tied to the central cable with plastic-coated twine. The plant tops are pruned about one month before the end of the harvest. Pruning the tops usually increases the fruits’ diameter in the last 3-4 inflorescences. With this trellising method, 10-12 inflorescences are picked from each plant. Planting a short-season variety is common in various countries, including the Mediterranean Basin. This method requires lower investment and fewer work days, and enables planting of another crop in the same year. 2. When the harvest season is longer than four months, a high crop wire system (at least 3.5 m) should be used. The plant tops are left upright throughout the harvest season. This method enables lowering of the central stem by releasing the twine from the hook on the crop wire. Before lowering the plants, all leaves on the central stem below the ripened or picked inflorescences should be removed, so that the stem from which fruit has been picked lies on the ground. In this method, the work of twisting plants on twine or string, pruning of side branches and other activities are performed when the plant tops reach the height of the crop wire. Therefore, elevated work carts are needed to reach the high areas. These carts are propelled forward either by electric motors or by mechanical means such as pedal and chain. One cart for every 0.2 ha is usually sufficient. The advantage of this method is that inflorescences with ripe fruit that are ready for harvest are at a convenient height for picking, especially when harvest wagons are used. It is recommended to cut the plants’ tops to stop growth about one month before the end of the planned harvest. In this trellising method, about 20-25 inflorescences are picked from each plant. 10 TRAINING METHODS 20 Plant spacing – cherry tomatoes Plant spacing of cherry tomato seedlings for single fruit or cluster harvest are the same as spacing of regular tomatoes. These seedlings are grown in double rows and the distance between row centers is 170-185 cm. However, the distance between the seedlings varies according to the number of stems growing on each plant. If there is one stem per plant, the distance between seedlings in the rows is 30-40 cm. This is recommended in light and sandy soils. When each plant has two stems, there can be a distance of 60-80 cm between plants. This is conventional in medium and heavy soils. The growing method of two stems on one plant is common and conventional when the variety has especially large fruit and the aim is to reduce the fruit size, or when grafted seedlings are used. Two stems from one plant Pruning the top branches to encourage development of two identical stems
  • 25. Support for cherry tomato stems The inflorescences of cherry tomato plants are large and are not harvested in a short period and at the same time, therefore it is recommended to tie cherry tomato stems to a support system to keep the fruit in inflorescence off the ground. The support system is made of bent black or galvanized iron rods, with a 6-8 mm diameter, a 50-60 cm surface width and a 3- 5 cm raised lip on each side to prevent the stems from sliding and falling off the support. After insertion into the ground, the surface height of the support is 40-50 cm. One support is installed every 1 meter along the row. In this way, when the plants 40cmabove thesurface 20cmin thesoil 4.0 4.0 60 cm 60cm 21 Diagram of hooks Various hooks are lowered and stems with unpicked fruit rest on the supports at a height of 40 – 50 cm, the fruit does not touch the ground. With this method the fruit is free of sand and does not rot as a result of contact with the damp ground. Training equipment One plastic or metal hook for each plant is used in high crop wire training. The hooks are wrapped with 8-10 m of plastic twine (recommended 900 m/kg). Twine from the previous crop should not be used, as it may carry viral disease or tear as a result of wear. New twine is attached to the hooks for each new crop. With low crop wires, the same type of twine is used without hooks and tied to the crop wires which are at a height of about 2.5 m. In both methods, the plants are tied to the crop wire by forming a loose ring around the central stem or by attaching the twine to the plants with plastic clips. The plants are wrapped around the twine about once every 7-10 days, Diagram of supporter Cherry tomato plants with and without supports
  • 26. depending on the temperature and the plant’s growth rate. The clips can also be used to attach the stems to the twine during growth, which eliminates the need for wrapping the plants around the twine, and significantly reduces breaking of the plant crowns. When tying the twine to the plants, the knot or hook on the trellising cable should be moved sideways by at least 50 cm from the center of the plant, so that the plant grows at an angle towards the row, with each row leaning in the opposite direction. This determines the direction of the plants when lowered, and the plant leans towards the row and not towards the work passages. 22 Inserting the twine into the stem Tying clip and inflorescence support Pruning suckers or side-shoots In order to shape the plant into one central stem, all the side-shoots growing near the leaves should be pruned throughout the growth period. The side-shoots are pruned when they are less than 5 cm long and removed from the base without leaving any remnants on the central stem. Late pruning leaves a wound which does not dry out quickly, and is susceptible to penetration of bacterial diseases and Botrytis. Side-shoots which are not pruned in time use nutrients and assimilates from the central stem and damage proper development of the plants. The cut branches and leaves should be collected into containers and removed from the greenhouse on the same day. If a crop with two stems on one plant is planned, as is conventional with cherry tomatoes and grafted plants, the first secondary branch under the first inflorescence should be left, or a plant with two stems should be purchased from the nursery. Removing leaves Old and yellowed leaves are removed after they have completed their function of photosynthesis. Lower leaves are removed to increase ventilation close to the ground. Leaves can be first removed when the plants reach a height of 1-1.5 m and produce 5-6 inflorescences. At this stage, 2- 3 lower leaves, which have limited efficiency and touch the ground, are removed. Leaves are removed again when the fruit in the first inflorescence is picked. All the leaves below the inflorescence are removed. When fruit in another inflorescence is picked, all the leaves below that inflorescence are removed. Leaves above the inflorescence with unripe fruit are not removed. In indeterminate tomato plants, movement of assimilate from the leaves to the fruit is generally characterized by transition of assimilates from one leaf below the inflorescence and another two leaves above that inflorescence. Therefore, it is important not to remove leaves above or below inflorescences where the fruit has not yet ripened. It is recommended to remove leaves on a clear and dry day. If leaves are removed on rainy or humid days, pesticide should be sprayed at the end of the process, especially with copper materials, to prevent bacterial disease. Sunburn as a result of over exposure to radiation Plastic clips and cluster supporter
  • 27. 23 Excessive removal of leaves Controlled removal of leaves The leaves have many tasks apart from supplying nutrients to the fruit: In summer, they provide shade for the green fruit and prevent sunburn or development of fruit with green shoulders. In winter, the leaves protect the fruit against chill by preventing heat radiation from the fruit to the greenhouse atmosphere. Moderating the temperature change of the fruit reduces the risk of fruit cracking, especially in autumn. When removing leaves, they should be broken off at the base, close to the central stem, without leaving stubs or parts of the leafstalk on the stem. The leaves are removed by holding the leafstalk close to the stem in one hand, and the plant in the other hand. The leaf is moved upwards and downwards until it is detached from the stem. An abscission layer (scar) forms where the leaf is removed, resulting in quick drying of the wound. However, when the stalk is not cut close to the stem, stubs are left. The wound does not dry out and it constitutes a source for penetration of pathogens. Movement of assimilates Supporting clusters In stress conditions, especially where there is lack of radiation, the cluster stems close to the plant’s central stem bend. This interferes with the movement of assimilates to the fruit in the cluster, and in extreme cases it causes complete abscission of the inflorescence from the stem, reducing yield and quality. Therefore, when there is an indication of this, it is recommended to install supports for the clusters. Increased radiation transmission between plants in the rows and between the row pairs reduces damage. Tomato clusters with a bent stem Cherry tomato clusters Left: A bent stem – defective color Right: Straight stem – normal color In order to achieve a high quality and quantity yield, tomatoes should be planted in mild climatic conditions, which are suitable for flowering and fruit set (see section that discusses climatic factors and their influence on tomato plants). Therefore, tomatoes should not be planted when climatic conditions develop to extreme temperature combinations. Temperatures that are higher than 32ºC in the day and 22ºC at night or lower than 18ºC in the day and 10ºC at night are considered to be detrimental to the tomato plant and disrupt the flowering and fruit set processes. The plants’ development rate and properties are also damaged. In high temperatures, the plants develop long and sparse internodes. In low temperatures, the plants develop short and dense internodes. Tomatoes can be planted in greenhouses in different seasons, and planting can be planned according to areas, required harvest period and required duration of yield. In Israel and countries with a similar climate, tomatoes can be planted at the end of summer. The crop can be harvested from the beginning of winter until mid-summer. 11 PLANTING SEASONS
  • 28. 24 In this way, high yields can be achieved, which justify the investments and various agro-technical treatments such as the continuous plant twisting and sucker removal. Although tomatoes can be planted in other periods, and in fact, almost year round, the yield periods are short and the yields level are lower compared to those received when planting in the optimum period. There may be various problems in the plants’ fertility in some planting periods, especially in summer, due to temperatures that rise to harmful values. Experience shows that planting in June and July is considered to be problematic, and the chances of receiving normative yields in this period are slight. In very hot regions, where both day and night temperatures are very high, it is not recommended to plant tomatoes from the end of spring until the end of summer. The PE films covering greenhouse roofs and the insect proof nets on sidewalls also raise temperatures to extreme and harmful values. In cold regions, it is not recommended to plant tomatoes in the winter, as plants may be damaged by the low temperature. However, if the greenhouse is equipped with a heater which operates in the winter (low temperature), tomatoes may also be planted in the cold months. Double-crop production is common in many regions. This method enables production of a high quality and quantity yield, without the need to invest in the equipment and labor used when growing with high crop wires. The disadvantage of the double-crop method is that production is not continuous and yields tend to be lower. This method is suitable where there are many greenhouses and production and marketing times need to be flexible. The period from planting until harvest is influenced by the variety, planting date and climatic conditions in the region. In the hot season, harvest of early ripening varieties should start after 60 to 65 days, and harvest of late ripening varieties should start after 75 to 85 days. However, when planting in the cold season, early ripening varieties are harvested after 100 days, while late ripening varieties require about 120 days until harvest. Lake of fertility (high temperature) Collapse of the locules (low temperature) 12 Indeterminate varieties, which are suitable for growing in greenhouses, are grown on one central stem by continuously pruning the sideshoots. Researchers are working to introduce favorable attributes related to fruit quality and disease-resistance. Varieties are selected after they have been studied in pilot plots, covering different seasons and regions. The tests include yield level, fruit quality, compatibility to local and export market demands and to different growing conditions. Great success has been achieved by breeding varieties that are suitable for growing in greenhouses and which are resistant to soilborne diseases carried by fungi and nematodes. Effort has been invested in breeding varieties that are resistant to viral diseases, especially TYLCV, which is carried by Bemisia tabaci (whitefly). If TYLCV-resistant tomato varieties with good yields and quality are developed, nets with a mesh density less than 50 mesh can be used. This will lead to improved climate inside the greenhouses by increasing passive ventilation. TABLETOMATO VARIETIES
  • 29. 25 Medium Very Good Very Good Medium Medium/ good Good Very Good Good Good Very Good Medium/ Good Medium/ Good Very Good Good Good Very Good Good Good Good Good Flattened globe Flattened globe Flattened globe Globe Flattened globe Globe Flattened globe Flattened globe Flattened globe Flattened globe Globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe ColorShapeVariety Resistance Daniela R-144 Shirley Anath FA-189 Nur 259 Dominique FA-593 Philippos Abigail FA-870 Graziella Cassius Astona Gironda Trofeo Charlotte FA-1402 Shannon Neely FA-1410 Rosaliya HT 1141 770-Sandrin Bonarda 9934-Mali Firmness Planting season V F1 F2 Tm V F1 F2 Tm V F1 F2 Tm V F1 F2 N Tm V F1 F2 N Tm V F1 F2 N Tm V F1 F2 Tm V F1 F2 Tm V F1 F2 Tm V F1 F2 Tm V F1 F2 Tm V F1 F2 N Tm V F1 F2 N Tm V F1 F2 Fr N Tm V F1 F2 Fr N Tm V F1 F2 Fr N Tm V F1 F2 Tm V F1 F2 Fr N Tm V F1 F2 Tm V F1 F2 N Tm Good Good Good Good Good Good Good Good Good Good Good Good Very Good Good Very Good Good Good Good Good Good Autumn/ Spring Autumn/ Spring Summer/ Spring Autumn/ Spring Autumn/ Spring Autumn/ Spring Autumn/ Spring Spring Spring Autumn/ Winter Autumn/ Spring Autumn Autumn/ Spring Autumn/ Winter Autumn Summer/ autumn Summer/ Spring Summer Spring/ Summer Summer Vigor Strong Medium Strong Medium/ Strong Strong Medium Very Strong Strong Strong Strong Strong Strong Strong Very Strong Very Strong Medium Strong Strong Medium Strong Table 5. Common single-harvest tomato varieties and different growing seasons The following tables present information about varieties that are suitable for growing in greenhouses and nethouses. The varieties in the table are recommended for planting in Israel, and may also be suitable for planting in Mediterranean countries, North Africa, Latin America and other countries with similar climatic conditions.
  • 30. 26 ColorShapeVariety Resistance Firmness Planting season Vigor Good Good Good Good Good Very Good Medium/good Medium/good Medium/good Good Good Good Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Flattened globe Globe Flattened globe Large globe Flattened globe Meitar FA-1907 Michaella FA-1903 Melissa FA-1415 Nemoneta Natalya Bonaque Colette HA-832 HA-3209 DRW-6478 Minhir Brillante FA-179 Nerissa FA-1420 V F1 F2 N Tm V F1 F2 Fr N Tm V F1 F2 Fr N Tm V F1 F2 N Tm V F1 F2 N Tm V F1 F2 N Tm V F1 F2 Tm V F1 F2 N Tm Ty V F1 F2 N Tm Ty V F1 F2 N Tm V F1 F2 Tm V F1 F2 Fr N Tm Good Good Good Good Good Good Good Good Good Good Medium Good Summer/ autumn Autumn Spring Autumn Autumn Autumn/ Spring Autumn/ Spring Autumn Autumn Autumn/ Spring Autumn/ Spring Spring/ Summer Strong Medium/ Strong Strong Strong Strong Strong Strong Strong Strong Medium/ Strong Medium Medium Table 5. Continuation
  • 31. 27 For example, Spain is considered to be a large vegetable producer, particularly of tomatoes. Tomatoes are produced year round for local and export markets. Production areas are distributed in different regions, including the mainland and Canary Islands. Spanish tomato production is characterized by its wide range of colors, sizes and shapes. Main varieties for different market segments in Spain: Cluster harvest: Pitenza, Ikram, Durinta. Single red fruit: Daniela, Jamile, Boludo, Kampala, Doroty, Eldiez, Bombay, Brillante Breaking color (Pinton): Isabella, Carolina, Tyrade, Caramba, Rafter, Raferty, Rambo, Salvador, Lido, Zinac Specialty: Patrona, Realeza, Evaluna, Cencara, Reva, Miriade Cherry tomatoes for single and cluster harvest: Alina, Conchita, Josefina, Karmina, Katalina, Natacha, Lupita, Salome, Shiren, Zarina. Resistance Code: Key to characterizing and identifying tomato varieties’ resistance and tolerance to pests: F1: Fusarium oxysporum f. sp. Lycopersici - race 1 F2: Fusarium oxysporum f. sp. Lycopersici race 2 V: Verticillium dahliae Fr, Cr: Fusarium oxysporum f.sp. radicis lycopersici crown and root rot P, K: Pyrenochaeta lycopersici - Corky root N: Root-knot nematode - Meloidogyne sp. Tm: Tobacco mosaic virus Ty: Tomato yellow leaf curl virus C: Leaf mold - Cladosporium fulvum-Fulvia Fulva Wi: Silver leaf Sw: Tomato spotted wilt virus (TSWV) Pto: Bacterial speck Lt: Powdery mildew Many local and international breeding teams are involved in the intensive activities surrounding breeding of tomato varieties. It can be assumed that the list of varieties may change according to progress of the breeding process. New varieties are usually selected because they have better yield, quality and resistances than the conventional varieties that are used. Cherry tomatoes are one of the tomato products that are grown in Israel and targeted for the local market as well as for US and European markets. Cherry tomato production is also common in many other countries. Production has expanded in recent years, because of longer shelf life and better taste. Single cherry tomato Cherry tomato clusters Cherry tomatoes in full bloom These tomatoes are characterized by round fruit, high- quality taste and long shelf-life. Cherry tomatoes are produced throughout the year, mostly in greenhouses and net-houses, with a small percentage produced in open fields. The optimal diameter of cherry tomatoes is in the range of 18 to 30 mm, however fruit with a 30 to 35 mm diameter is also marketed, although on a smaller scope and to special markets. The cherry tomato is sorted into groups according to diameter and packed in different packages, according to the buyers’ requirements. Cherry tomatoes can be grown for cluster harvest. These are special varieties which have clusters with symmetrical shapes, uniform fruit size and uniform ripening. In cluster cherry tomatoes the fruits are connected symmetrically, in a fishbone shape, to both sides of the inflorescence and create a cluster with 8 to 12 fruits. 13 CHERRY TOMATO VARIETIES
  • 32. 28 Cherry tomato clusters before harvest Defective fertility in cherry tomatoes - high temperature Table 6. Common cherry tomato varieties for greenhouse production Cluster harvest Single harvest Variety Resistance - VF1 Tm F N Tm F N Tm V F1 Tm Pto V F1 F2 Tm F1 N Tm C5 V F1 F2 Fr N Tm Pto V F1 F2 Fr N Tm Pto Josefina R-139 Bambino Zarina Natacha Dominion DRC-316 Damita FA-1392 Katalina Alina Karmina V F VF Tm Naomi R-124 Camellia R-819 V F1 F2 Fr Tm C5 Wi F1 F2 N Tm F1 N Tm C5 F1 Tm V F1 Tm Pto V F1 F2 N Tm Ty C5 Conchita Shiren Fa-1335 Rubino Top Victories Diamante TyTy (C1002-20) Planting periods for cherry tomatoes Planting periods for cherry tomatoes are directly influenced by supply and marketing agreements which are determined between the grower and exporter and of course by the climatic conditions in the region. Similar to regular tomatoes, cherry tomatoes are also sensitive to extreme temperatures, both high and low. The planting season should be planned so that most of the growing, flowering and fruit set take place when there are no continuous extreme temperatures. Under extreme climatic conditions, there may be disruptions in the plants’ fertility, inflorescence shape and flower size, and the flowers’ fertility may be defective.
  • 33. Marketing of vine ripened cluster tomatoes has recently expanded in many countries. This innovative product is marketed through a marketing channel which supplies tomatoes with a fresh appearance: fruit on a cluster with the green cluster stem and calyx being hallmark signs of recently harvested fruit and thus freshness. Varieties that are suitable for cluster harvesting must have a stem and calyx that remain green and fresh for a long time and prevent the fruit from dropping off the cluster during transportation. All tomato varieties have fruit which grow on a truss/cluster; 14 GROWING TOMATOESFOR CLUSTER HARVESTING 29 Clusters: green and ready for harvest Cluster tomatoes however varieties that are suitable for cluster harvest have a central axis with the fruit attached symmetrically in a fishbone shape. Tomatoes that are harvested in clusters can be characterized and classified into groups by the fruit size and diameter of the fruit on the cluster. Each group has varieties which meet different marketing requirements. Groups according to fruit diameter: 1. Regular tomatoes: fruit with a 55 to 75 mm diameter, 4 to 6 fruits per cluster. 2. Cocktail/baby tomatoes: fruit with a 35 to 55 mm diameter, 5 to 8 fruits per cluster. 3. Cherry tomatoes: fruits with a 20 to 35 mm diameter, 8 to 12 fruits per cluster. The chance of receiving a good cluster/truss, which is uniform in size, shape, color and firmness, depends on varieties which are able to flower and ripen fully in a relatively short time between opening of the first and last flowers in the inflorescence. Five to seven days is conventional for full flowering. This enables production of a quality cluster with uniform ripening. Production of clusters with high quality and uniform fruit requires suitable and stable climatic conditions through- out the growing period. Changes in climatic conditions, especially in temperature, have a decisive influence on the character and shape of the clusters that develop. Cluster shaping Uniformity of the fruit size in the inflorescence is achieved by agro-technical treatments applied throughout the growing period. These treatments include removal of the first flower, when this flower is too large or clearly deformed. This is conventional in varieties that are targeted for cluster harvesting and which have particularly large fruit. Pruning the last flowers in the inflorescence, after fruit set of a minimal number of fruit, is required according to the groups, which were defined by fruit diameter. This is conventional in varieties with a large number of flowers in the inflorescence, especially cherry varieties. Planting dates for cluster harvesting Varieties which are designated for cluster harvest should be planted when the climatic conditions are good for fruit set from the first inflorescence, so that fruit set is not damaged by high summer temperatures. Unsatisfactory fruit set and ripening results in non-uniform clusters which are not suitable for marketing as cluster tomatoes. It is recommended to strive for the optimal planting time in different areas, in order to achieve perfect ripening beginning with the first cluster. In winter, it is recommended to operate a heating system in greenhouses for both agronomical and economical aspects: Production of a normal inflorescence Uniform flowering and fruit-set rate in the inflorescence Uniform ripening of the fruit in the cluster Increase of yield by accelerating the fruit’s ripening rate Increase in the number of clusters that are picked
  • 34. 30 Following the market’s saturation with regular tomatoes, new tomato products are being developed, which are designated for local and export markets. Development is conducted in different, parallel and similar paths, from the aspect of the goals and objectives. Developing new products involves professional agro-technical investment, as well as development of special markets, which means Cocktail tomato cluster, 35-50 mm Plum tomatoes Midi-plum tomatoes Mini-plum tomatoes Table 7. Tomato varieties suitable for harvesting in clusters Variety CommentsResistance Symmetrical cluster, medium-sized fruit, good firmness, medium color V F1 F2 N TmPrincess- AB 2536 Symmetrical cluster, medium-sized fruit, good firmness and color. Requires special variety treatments - sensitive to microelement deficit. V F1 F2 TmDorinta Symmetrical cluster, medium/large-sized fruit, good firmness, medium color, suitable for growing in brackish conditions. V F1 F2 N TmDominique FA-593 Symmetrical cluster, medium/large-sized fruit, good firmness, medium color, suitable for growing in brackish conditions V F1 F2 TmDaniella-R 144 Symmetrical cluster, 5-6 fruits in cluster, good firmness and color, medium-sized F1 F2 N TmIkram Symmetrical cluster, globe, 5-7 fruits in cluster, good color, medium-sized V F1 F2 Fr N Tm C5 Risoka Symmetrical cluster, 6-8 fruits in cluster, medium color and medium-sized V F1 F2 TmPetenza Symmetrical cluster, 5-7 fruits in cluster medium-sized V F1 F2 TmFH-1476 Symmetrical cluster, medium sized fruit, 6-8 fruits in cluster medium-sized V F1 F2 TmFA-62203 Symmetrical cluster, globe,good color, relatively small-medium size of fruits V F1 TmR-62202 15 NEW TOMATO PRODUCTS changes in consumer behavior and the acceptance of the new products as something new and innovative and not simply an alternative to tomatoes. The production and marketing of the new products demands perseverance and professionalism because of the time it takes for the market to absorb new products. Main properties of the new products: Unconventional shape and color Consumed in smaller amounts High value and returns
  • 35. 31 Colorful cluster tomatoes Development of the new product requires the following: Definition and characterization of the product Agro-technical development Market development Penetration of product New products include: Deep globe tomatoes: with different colors and sizes, such as plum, midi-plum and mini-plum Colorful tomatoes: orange or yellow, as well as the conventional and common red. Can be grown for single or cluster harvest. Flavor tomatoes: with especially high TSS and sugar level. Different sizes, deep globe or globe. Can be grown for single or cluster harvest. Beef tomatoes: large tomatoes, which are flat and have a diameter of over 82 mm. When the fruit is cut in half, its fleshiness and large number of locules are apparent. Tomatoes with special nutritional value or with high levels of lycopene or β carotene, which are known to have special medical value. Colorful deep globe tomatoes Orange cherry tomatoes Single colorful tomatoes Yellow cherry tomatoes Flat beef tomatoes Aranka tomatoes
  • 36. Cencara-deep globe fruit 32 Italdor-very deep globe fruit Mix of tomato products Mini-plum packed for export Regular tomatoes Yellow and red cherry tomatoes Cherry tomato Cluster Marinda (Marmande type)
  • 37. Table 8. Varieties of special tomatoes (Different Products) Single/cluster Variety Features Goldita DRC-89 Yellow, globe cherry FA-1339 Yellow, globe cherry Drk-941 deep globe cocktail, deep red with green stripes Orangeno DRC-1039 Orange, Mini plumDrk-927 Orange, globe cocktail Melody AB-8061 Mini-plum deep globe cherry DRC-353 Mini-plum deep globe cherry DRC-377 Mini-plum HA-4801 Mini-plum HA-1331 Mini-plum FA-1328 Mini-plum Revello Mini-plum - mini S. Marzano FA-654 Deep globe midi-plum Columbus-RZ Deep globe midi-plum Flavorino DRC-186 Deep globe midi-plum NR-8387 Midi-plum 98-AB-550 Deep globe plum FA-1413 Deep globe plum Romana Deep globe plum FA-62201 Deep globe plum FA-1463 Deep globe plum Ovata-RZ Deep globe plum Pisa Deep globe plum Cencara Deep globe plum Oscar Italdor Long plum, S. Marzano type Aranka Medium cocktail, globe Rosalinde FA-631 Large cocktail, globe FA-643 Large cocktail, flattened globe BabyMaya FA-646 Medium cocktail, globe FA-612 Globe cocktail Single Harvest Single Single Single Cluster Single Single Single Cluster Single Single/cluster Single/cluster Single Single Single/cluster Single/cluster Single Single Single Single Single Single/cluster Single/cluster Single Single Single Cluster Cluster Cluster Cluster Single Resistance Tm C5 V F1 Tm V N Tm V F1 F2 Tm V F1 F2 Tm C5 V F1 N Tm V F1 F2 N Tm V F1 F2 Tm C5 V F1 F2 Tm Pto V F1 N Tm F Tm VF1 FrNTmPto VF1 F2 Tm VF1 F2 FrTmC5 VF1 F2 NTm VF1 F2 NTm VF1 F2 NTm VF1 F2 Tm VF1 F2 NTmLt VF1 N Tm VF1 Tm VF1 F2 NTm VF1 F2 NTm VF1NTm C3 VF1F2FrNTmC5 VF1 NTm V F1 F2 Tm C5 Wi VF1 F2Tm VF1 F2Tm VF1 F2FrNTm VF1 F2 Tm DRK903 VF1 F2 Tm Orange, medium size Marinda VF1 Tm Marmande type, flattened rib Single/cluster 33 Long plum, S. Marzano type
  • 38. 34 16 PARTIALRESISTANCE TO ROOT KNOT NEMATODES There are many types of nematodes that cause damage to tomatoes. The most common type is the root knot nematode (Meloidogyne spp.), which causes a disease that is recognized by swollen nodules on the plant roots. Nematode infestation severely damages the plants, causing lack of absorption of water and nutrients. The plants become weak and the yield is low. In severe infestation, the knots on the roots multiply, until absorption of water and nutrients stops completely and the plants wilt and die. There are four common types of Meloidogyne spp. nematodes: M. Javanica, M. Incognita, M. Arenaria and M. Hapla. Today, tomato varieties which are resistant to root knot nematodes contain the MI gene. This gene provides resistance to M. Javanica, M. Incognita and M. Arenaria species, but not to M. Hapla species. The resistance provided by the MI gene breaks down in soil temperatures above 27-28ºC, causing heavy damage to the plants, sometimes to the extent of collapse and wilting. If a farmer plans to plant a nematode-resistant variety in greenhouses during the hot season, it is recommended to apply all possible means to ensure that the soil (or growing medium) temperature does not exceed 27-28ºC. If the soil is infested with nematodes, it is recommended to sterilize before planting, applying one of the methods that reduces the nematode population. Resistant plants develop small knots on the roots, even when the soil temperature is not high. This may occur in resistant plants that are heterozygous around the MI gene (contain only one copy of the gene in each cell). In this case, the resistance does not break down and the plants continue to develop normally, without any damage to yield level, despite the appearance of small knots on the roots. Diagram of nematode symptoms in various plants Right: resistant variety; left: sensitive variety Propagation by grafting is a well-known and conventional method used in orchard and rose crops. Over the last several years, grafting has been introduced in vegetables. In this method, a scion of a variety or cultivar, which is capable of producing a quality commercial yield, is grafted onto rootstock which is capable of growing in harsh soil conditions. These adverse conditions include soil infested with nematodes and soilborne diseases, lack of aeration, high salinity and other problems. In this way, a susceptible variety/cultivar can be grown in soil which was previously unsuitable, achieving commercial yields. Propagation by grafting has become conventional in vegetables, especially tomatoes, and it serves as a means to control soil problems, such as root diseases. In some cases, it was found that the grafted plant develops greater vegetative growth as compared to a regular plant. The possibility of growing two stems on each grafted plant is being examined. This will reduce plant density and of course save the grower money. Tomato rootstock varieties have a wide range of resistance to soilborne diseases. The grafting method can therefore reduce the need to sanitize soil with every planting. Moreover, the use of methyl bromide can be dramatically reduced and even eliminated as grafted varieties, together with a range of new chemicals to control soil diseases, are used. 17 ROOTSTOCK AND GRAFTING Grafted plants
  • 39. 35 Growing three branches from a grafted plant (cherry tomatoes) Growing two branches from a grafted plant (regular tomatoes) Grafted plants -attached by plastic clips Generally the rootstock is a hybrid plant, as a result of cross breeding of wild species such as Lycopersicon hirsutum with the cultivated type Lycopersicon esculentum. The combination of the two types is the main factor influencing the vigor and strength of the rootstock and the grafted plants. Advantages of grafting: Resistant rootstock is widely available Wide resistance range for soilborne diseases Strong vegetative growth and reduced plant stress Methyl bromide substitute Reduced need for crop rotation Disadvantages of grafting: High production cost Risk of disease infection during grafting Investment in expensive mechanization Limited production capacity in nurseries Risk of incompatibility between scion and rootstock Success in grafting tomato plants requires know-how and skill in performing the process, and especially in determining the suitable planting depth in the field so as to prevent the risk of adventitious roots from the scion, which may penetrate into the soil and take root. If such a root system develops, the scion may be infected by a soilborne pathogen to which it is susceptible. Transplanting of grafted plant Grafted seedling Incompatibility / compatibility
  • 40. 35 Growing three branches from a grafted plant (cherry tomatoes) Growing two branches from a grafted plant (regular tomatoes) Grafted plants -attached by plastic clips Generally the rootstock is a hybrid plant, as a result of cross breeding of wild species such as Lycopersicon hirsutum with the cultivated type Lycopersicon esculentum. The combination of the two types is the main factor influencing the vigor and strength of the rootstock and the grafted plants. Advantages of grafting: Resistant rootstock is widely available Wide resistance range for soilborne diseases Strong vegetative growth and reduced plant stress Methyl bromide substitute Reduced need for crop rotation Disadvantages of grafting: High production cost Risk of disease infection during grafting Investment in expensive mechanization Limited production capacity in nurseries Risk of incompatibility between scion and rootstock Success in grafting tomato plants requires know-how and skill in performing the process, and especially in determining the suitable planting depth in the field so as to prevent the risk of adventitious roots from the scion, which may penetrate into the soil and take root. If such a root system develops, the scion may be infected by a soilborne pathogen to which it is susceptible. Transplanting of grafted plant Grafted seedling Incompatibility / compatibility
  • 41. 36 Scion roots infected by nematode Table 9. Resistance of common and experimental rootstock suitable for grafting of different tomato varieties Rootstock CompanyResistance BEAUFORT ENERGY HE-MAN UNIGENE AX-105 MAXIFORT W-393 6153 6776 SUKKETO RESISTAR - 4402 SPIRIT TRIOFORT – 217 V F1 F2 Fr N K Tm V F1 F2 Fr N K Tm V F1 F2 Fr N K Tm V F1 F2 Fr N K V F1 F2 Fr N K Tm V F1 F2 Fr N K Tm V F1 F2 Fr N K Tm V F1 F2 Fr N K Tm C5 V F1 F2 Fr N Tm C5 V F1 F2 Fr N K Tm V F1 F2 Fr N K Tm V F1 F2 Fr N K (partly) Pto Tm V F1 F2 F3 Fr N Pto Tm DERUITER VILMORIN S&G UNITED-GENETIC AGROTIP DERUITER WESTERN SEEDS RIJK ZWAAN BRUINSMA KANEKO SEED HAZERA NUNHEMS A.B - SEEDS Resistance data on varieties and rootstocks in Tables 5-9 was submitted by the seed companies Tomato flowers contain both male parts (stamens and pollen grains) and female parts (ovaries, ovules, styles and stigma). In most cases, the flowers are self pollinated. However sometimes there is cross pollination, especially by insects. After the flower buds open, the pollen chambers open and pollen spills onto the stigma. The pollen grains stick to the style, and reach the ovaries and ovules, where fertilization takes place. After the ovules are fertilized they become seeds and the fertilized ovule starts to grow and develop until its final size. The fruit size and shape are influenced by the number of seeds which develop inside it. A flower that has been fertilized with a good quantity of pollen may produce fruit with a shape and size that are compatible with the variety, while a partially fertilized flower may produce irregular and small fruit, since it contains fewer seeds. In open-field production under optimal growing conditions, there is cross and self-pollination in the tomato flowers. The natural wind improves the propagation process and encourages the opening of the pollen chambers and spilling of pollen. In plants which are grown in greenhouses, self- pollination is often only partial and insufficient to produce a good yield. Therefore various methods are applied to assist the pollination process. 18 POLLINATION AND FRUIT SET OF GREENHOUSE TOMATOES Methods to improve pollination in greenhouses Vibrator (electric bee): A battery-operated device with a vibrating unit at the end touches the inflorescence stem, vibrating the flowers. The pollen grains are released from the stamen and fall onto the stigma. Air pulsator: A motorized backpack sprayer with an air-blast unit shakes the plants. The air currents release the pollen grains. Bumblebees: The bumblebee is attracted to the tomato flowers which do not have nectar and collects pollen grains from the flowers. Common honeybees are only attracted to flowers with nectar. Use of bumblebees has become the most common method for pollination of tomato flowers. Details of this method appear later on in this booklet. A vibrator or air pulse is applied every one to two days, in the late morning after humidity in the greenhouse has dropped and the flowers are dry. When wet flowers are shaken, the pollen is not released properly, resulting in defective fertility. The tip of the electric bee is placed onto the inflorescent stem and operated for one or two seconds. The entire inflorescence is shaken and the flowers are pollinated. Tomato flowers do not open up together, therefore the process should be repeated whenever there are new open flowers in the inflorescence. Small fruit as a result of faulty pollination
  • 42. 3 7 Shaking an inflorescence with an electric vibrator Flowers and fruit of different ages in an inflorescence Table 10. The influence of climatic conditions on the number of pollen grains of the stigma after vibrating Comment: Estimated average number of pollen grains per flower: 76,000 Time 08:00 Air temperature Relative humidity No. of pollen grains on stigma 10ºC 95% 225 10:00 16ºC 81% 375 12:00 19ºC 70% 450 Table no. 11: Improved yield per plant with different treatments in greenhouses – Angela variety (according to Rilska I.) Use of growth hormones for fruit set In extreme temperature conditions, when it is either very hot or very cold, and there is no pollen in the flowers for three consecutive days, bees or vibrating will not be effective. In this case, it is recommended to use growth hormones to improve fruit set. The hormones should be sprayed onto the inflorescence only, and not onto the plant tops. The materials recommended for use belong to the ß- naphthoxy acetic acids. These hormones enable division and growing of cells in tomato plants without the need for the pollination process. Fruit formed after spraying with growth hormones are usually seedless. The hormones are sprayed with the concentration that is recommended by the manufacturer, as it appears on the label, and with a spraying volume of 70 to 100 l/ha in each spraying cycle. Excessive use of hormones should be avoided as this may increase fruit puffiness. Each inflorescence is sprayed twice. The first spray is when three or four flowers have opened in the inflorescence, and the second spray is when a new inflorescence has developed, also with three or four open flowers. From this point, the first spray is on the new inflorescence, and the second is on the previous inflorescence, and so on. This method ensures that each inflorescence is sprayed twice only, since not all the flowers in the inflorescence open together. The second spraying is necessary, since it ensures full fruit set in all the flowers in the inflorescence. Treatment Average fruit weight (g) Fruit weight per plant (kg) 5.32 4.86 4.17 3.72 43 21 6 ...... 89 83 77 72 24 15 7 ....... Vibrating with a vibrator Vibrating with air pulse Spraying with hormones Control Improvement (%) Improvement (%)
  • 43. 38 Spraying flowers with growth hormones Hollow fruit resulting from a high concentration of growth hormones Distorted foliage resulting from a high concentration of growth hormones Hormonal fruit set without side effects Blossoms which remain vital after treatment with growth hormones Note: In many cases it has been observed that following spraying with hormones, the petals remain close to the fruit and below the sepal. In high humidity, the petals are susceptible to pathogenic fungi, mainly Botrytis and Rhizopus. These fungi create a fuzzy mat of spores and mycelium which develop rapidly and result in fruit rot and great damage.
  • 44. Pollinating services: A standard bumblebee hive contains one queen and dozens of workers, larvae and eggs. One hive is suitable for pollinating about 0.2 to 0.25 hectares of greenhouses for five to eight weeks. The first hive that is installed constitutes the basic population, after which other hives are introduced, or old hives are replaced with new ones. Cherry tomato varieties have a large number of flowers and therefore, there should be twice as many hives per unit than in regular varieties. The petals of the fruit pollinated by bumblebees adhere to the fruit base and dry together with the style. These usually abscise before harvest. Bumblebee activity on the flower In tomatoes, the bumblebee’s visit to the flower is visible within a few hours, because it leaves a rusty-brown spot on the flower’s pistil. If no spots are visible, then the bumblebee’s activities have ceased or been reduced, and inquiries should be made with the pollination service provider. Activities may cease for a number of reasons, such as: Ageing and degeneration of the hive population Presence of toxins on the plants High temperatures in the greenhouses The hive entrance remained closed after spraying Lack of grain pollen in flowers 39 Using bumblebees to pollinate tomatoes in greenhouses Advantages: The bumblebee is a large insect (2 to 4 cm long) covered by black hairs, with two lateral yellow lines and a white stomach. This bee has three significant advantages which provide it with an advantage over use of other pollinators, including the honeybee: The bumblebee shakes the flower with its buzz pollination mechanism, which is its specialty. Tomato flowers in greenhouses or net-houses need to be shaken for pollination, and the bumblebee is most effective for this purpose, and is superior to any manual alternative, such as an electric bee, air pulse or application of hormones. Bumblebees are less sensitive to extreme weather than the honeybee. For example, when the temperature is below 10ºC, with rain and clouds, the honeybee stays in the hive. However, these conditions do not interfere with the bumblebee’s activities. When the greenhouse is opened for ventilation, the bumblebee does not fly out to search for nectar and pollen. It stays in the greenhouse and does not search for other pastures. In general, the bumblebee’s orientation and survival in a closed greenhouse is superior to that of the honeybee. This comparison does not indicate that the honeybee is suitable for pollinating tomato flowers. On the contrary, it is not at all suitable for pollinating tomato flowers. Basic principles for using bumblebees in greenhouses Bumblebee hives Tomato inflorescence pollinated by bumblebees A bumblebee at work Brown spot on the pistil – sign of bumblebee activity
  • 45. 40 Perfect pollination – high quality fruits Comparison of methods for pollinating tomato flowers: shaking compared to bumblebees(bombusterrestris),according to Pressman E. Tests show that bumblebees are more effective pollinators than electric bees or air pulses, especially in low temperatures and when there are fewer pollen grains in the flowers. This effectiveness apparently stems from the bumblebee’s frequent visits to and shaking of the flower in these difficult conditions. Shaking by electric bee, air pulses or bumblebees to increase pollination is only possible when there are pollen grains in the flowers. In winter, when night temperatures drop below 10ºC and day temperatures are also low, the quantity and vitality of the pollen grains in the tomato flowers decline. This is also relevant in summer, when temperatures are very high in the day and also at night. There is a trend of low fertility in the tomato flowers, which is expressed in few pollen grains in the flowers and in elongation of the style and stigma beyond the anthers, and in certain cases, the flowers do not open.
  • 46. 41 Sugar water: A sugar-water solution is supplied to hives as a substitute for nectar which is not present in tomato flowers. The solution constitutes an integral part of the hive. The feeding system provides an ongoing supply of sugar-water, which is essential for the hive’s performance for the entire period that it is in use. Placing the hive: Place the hive in a prominent position in the greenhouse, where it is sufficiently ventilated (in winter and summer) and shaded (in the hot season). The hive should not be exposed to direct sunlight. Place the hive on a support pole, which has been especially planned for this purpose. Spread a line of insect-trapping glue on the lower third part of the pole to prevent ants from entering the hive, as this may result in disquiet in the colony. Ensure that the area around the hive is free of vegetation. Train the plants away from the hive. If possible, the foliage should provide shade for the hive. After placing the hive, allow the colony inside to calm down, and after a few minutes, carefully open the exit hole by removing the shutter that blocks it. The bees will leave the hive and start their orientation flight, which provides them with the ability to find their way back to the hive with no problem. A hive which is set up close to sunset should not be opened until the following morning. The original position of the hive in the greenhouse should not be changed. During the first three days, until the hive has entered into complete activity, an electric bee, air blower or hormones should be used. Manual support should only be terminated when the bumblebee has become fully active. The bumblebee and Integrated Pest Managment (IPM) in the greenhouse The use of bumblebees in a greenhouse requires a different pest control approach. In principle, non-chemical pest control alternatives should be used in the greenhouse. For example, natural enemies, which have no adverse effect on bumblebees, can be used to control insects such as red spider mite and leafminer. Pesticide suppliers provide lists of pesticides that can be used with bumblebees, based on experience in the field, and results of laboratory and semi-laboratory tests. The list is divided into groups according to the level of severity of thesubstance’saffectonthebees,andIPMisbasedaccordingly, combining the presence of the bees in the greenhouse with the application of pesticides. The introduction of bumblebees into tomato greenhouses has clearly led to a significant reduction in the use of pesticides, which was an unforeseen benefit. Reduced use of pesticides allows the development of unique marketing brands under the label of reduced pesticide products. Reduced pesticide use hasalsoresultedinsignificantsavingsinpestcontrolexpenses. The fertigation system The irrigation and fertilization (fertigation) system for tomato production in greenhouses allows maximum distribution uniformity to the entire area and proportional injection of fertilizer solution into the irrigation system. The irrigation system includes drip laterals for each row. The distance between drippers is determined by the planned distance between plants, so that each plant has its own dripper. In light soils, the drippers are closer together, so that the entire growing strip is wetted, without wasting large amounts of water and fertilizers. In these cases, there are two drippers for each plant. The seedlings are planted next to the drippers. The dripper discharge is 1.5 - 2 l/h, depending on the type of soil and hourly discharge in the plot. Heavy soils have a slow infiltration rate, therefore it is not recommended to use high volume drippers, in order to prevent runoff as a result of excess discharge. The fertilizer system generally includes one central pump for injecting the principal fertilizer and another pump for injecting other elements such as iron, manganese, magnesium and calcium, when necessary. Large greenhouses with a number of varieties and different plant ages, which require different water applications and frequency, should have an irrigation system which allows control and command of smaller field units. This also supports the operation systems, discharge capacity and control system in the fertigation head and allows application of water and nutrients according to the requirements of the different varieties and planting ages. Irrigation The plant’s water requirements are influenced by many factors. The main factors are: climate, including temperature, relative humidity, radiation and wind; and vegetative growth, which is influenced by the age and type of plant and the leaf shape. A combination of these factors or each one separately, may change the evapo- transpiration rate, changing the plant’s water requirements. 19 IRRIGATION AND NUTRITION A combination of a number of agrotechnical factors in greenhouses for tomato production constitutes a guarantee for the success of IPM. These factors include: resistant varieties; soil covering; insect protection nets; UV-blocking plastic covers; and use of bumblebees for pollination. All these factors, together and separately, contribute to reduced use of pesticides.
  • 47. Irrigation principles After planting, the irrigation application rate is increased more than the plant’s requirement. The irrigation frequency is one or two daily applications, depending on the season and soil type. This special regime creates suitable conditions and maintains wetness of the root zone, which encourages quick establishment of the seedling in the soil. When the plant has become established in the soil (7 - 10 days after planting), irrigation is applied according to 30 - 40% of the pan evaporation rate. The irrigation schedule according to pan evaporation increases gradually up to 65-80%, at the stage when the plant fully covers the surface (flowering and fruit set of the fourth and fifth clusters). In light soils, hot climates or with brackish water, the coefficient may reach 100% or more. Irrigation with this high coefficient prevents accumulation of salts in the upper soil layers and reduces the risk of sudden lack of water which creates stress conditions. Irrigation frequency varies according to soil type. In sandy soils, irrigation is applied once or twice a day. In medium- heavy soils, the frequency will be longer, according to the water content in the root zone after irrigation. In any case, the irrigation frequency should not be more than three to five days, as fertilizers should be applied in short intervals. In general, irrigation intervals should not be too short, as this does not enable development of a deep and branched root system. A deep, well developed root system allows absorption of sufficient water and nutrients, especially when there is a great load of fruit on the plants or under extreme climatic conditions, such as hot winds, when the plant’s water requirements increase. Table 12 discribes the radical differences of daily evaporation rates among regions in Israel, even though it’s a small country. The details in the table are used to set the daily evaporation coefficient. Irrigation control Irrigation control includes a basic control mechanism to monitor irrigation and ensure that it is indeed conducted as planned. Awater meter is installed at the plot head and irrigation duration and its compatibility with the requirements is examined periodically, taking into account the area discharge and water which was allocated for that irrigation application. Another method of irrigation control uses tensiometers which provide information regarding the daily water application required and the timing of the next irrigation. 42 Factors influencing evaportion rate The above figure presents the factors that influence the plant’s evapo-transpiration rate and water requirements. Table 12. Daily evaporation rate in months, multi-annual averages in mm/day Month Station 1 2 3 4 5 6 7 8 9 10 11 12 Akko Geva Carmel Ramat David Eden Station Ein Hahoresh Beit Dagan Sde Moshe Erez Gilat Besor Station Jericho Ein Yahav Eilat 2.3 3.1 2.1 1.7 2.4 1.8 2.8 1.9 2.9 2.6 2.4 3.2 4.2 2.8 3.6 2.2 2.3 2.8 2.4 3.0 2.3 3.4 3.7 3.4 4.5 5.5 2.6 4.5 3.4 3.4 3.9 3.5 4.2 3.5 4.9 4.9 4.5 6.5 7.5 5.0 5.2 4.4 5.8 4.8 5.0 5.6 4.6 6.7 6.9 6.8 10.1 9.8 6.0 5.8 6.3 8.4 5.7 6.2 7.8 6.0 8.3 8.0 8.3 11.5 12.5 6.8 6.6 8.9 9.8 6.3 7.0 8.8 6.4 9.4 8.8 10.5 12.9 14.4 6.9 6.6 8.5 10.2 6.5 7.0 8.5 6.8 9.3 8.8 10.5 13.1 14.4 6.8 6.2 7.9 9.5 6.0 6.6 7.8 6.3 8.6 8.0 9.7 11.5 13.6 6.0 5.6 6.9 8.2 5.3 5.8 7.2 5.5 7.3 6.7 7.9 9.9 11.7 4.6 4.6 4.9 5.8 4.0 4.3 5.4 4.1 5.7 5.3 5.7 7.2 8.5 3.4 4.0 3.6 3.3 2.9 2.7 3.9 2.5 4.1 3.9 3.5 4.4 6.1 2.3 3.2 2.2 1.9 2.3 1.8 2.7 2.0 3.1 2.6 2.2 3.1 4.4
  • 48. Extractor: Extracts the soil solution and enables the grower to check the nutrient elements in the soil solution. In this way the quantity of fertilizers used can be adjusted to maintain optimum growth. Tensiometers: Used to control irrigation and soil moisture. They help determine the quantity and frequency of irrigation. Nutrition The tomato plant’s nutrition requirements are influenced by the basic requirements for establishing vegetative mass, stems and foliage, as well as from the yield quantity that is expected in a specific time. The plant’s nutrition requirements have been examined in many studies, which have calculated the quantity of dry material produced by the plant and the percentages of the different nutrient elements in the leaf, stem and fruit tissue. As a result of this work, conventional fertilizer formulas were formulated. Most of the studies demonstrated that there is a higher potassium concentration in the fruit than in the leaves, while there is a higher nitrogen concentration in the leaves than in the fruit. The phosphorus concentration is similar in both leaves and fruit. There is also reference to the plant’s requirements regarding other nutrient elements, and according to the findings, Ca, Mg and SO4 elements are also taken into account when determining fertilizers and fertilizer formulas. The microelements Mo, B, Mn, Cu and Fe in the plant tissue are checked in the same way, and their concentration in the fertilizer compound is determined accordingly. Evaporation pan Mercury tensiometers Tensiometers and Extractors Electronic tensiometers 43 It is recommended to place two tensiometers stations in every plot (variety X planting date). In medium to heavy soils, three tensiometers should be placed at each station, at a depth of 25, 50 and 75 cm. The tensiometers are installed at a distance of 10 cm from the dripper and the plant. The upper tensiometer is inserted at the center of the root zone and provides information on irrigation timing. The tensiometer at the bottom part of the root zone indicates whether the water application wetted the entire root zone. The deeper tensiometer displays whether part of the water application penetrates too deeply and is wasted, or whether all the water remains in the root zone area. In light soils, tensiometers are installed at depths of 20, 40 and 60 cm. These tensiometers operate similarly to those that are installed in medium-heavy soils. The tensiometers should be read every day at a fixed time, preferably in the morning, and the readings should be recorded continuously. Entering the data into a graph contributes to analysis of the irrigation process and helps to draw conclusions for future use. New technology of electronic tensiometers are used in tomato greenhouses. The data and information about the soil tension or water content in the soil are transferred to the farmer’s PC, who consequently can control and manage the irrigation intervals and the water amount without being physically in the field.
  • 49. As well as the basic chemical fertilizers, it is recommended to add organic compost to the soil once every two years. The compost should be well prepared and applied at a volume of 40 - 50 m3/ha, when the soil is being prepared and cultivated. Fertilization during the season During the initial growing period, in the first one or two weeks, when the plants are taking root and becoming stabilized, it is customary to apply fertilizer with a nitrogen: phosphorus: potassium ratio (N:P2O5:K2O) of 1:1:1, which also contains the required level of microelements. This encourages development of a branched and deep root system. The required daily applications are about 1,000 to 1,500 g/ha of nitrogen. Another compound fertilizer is applied when the first inflorescence appears, at a ratio of 1:0.3-0.5:1.5-2, and the average daily requirements of nitrogen are 2,500 to 3,000 g/ha. This is gradually increased to the maximum level of 4,000 to 6,000 g/ha/day of nitrogen at the flowering stage and in fruit set in four and five inflorescences and throughout the harvest season. After cutting off the plant tops, fertilizer volume can be reduced by 50 – 60%. Proportional fertilizer is started according to 100 to 150 ppm nitrogen in the flowering of the first inflorescence, and the concentration is increased up to 180 to 200 ppm of nitrogen in the stage of full coverage. The phosphorus and potassium concentrations are calculated according to the nitrogen concentration, at a ratio of 1:0.3-0.5:1.5-2.0. A study conducted in the Besor region (B. Bar Yosef) demonstrated that in the mid-winter harvest stage, the optimal nitrogen level for a high quality yield is 200 ppm of nitrogen in fertilizer, where the N-P-K ratio is 1:0.3-0.5:1.5-2. Other studies in Israel and other countries showed similar results for the optimum fertilizer concentration in the harvest stage. This ratio is recommended in the harvest stage in order to receive a higher quality fruit. In spring, the daily fertilizer quantities are maintained, however since the daily water applications increase as a result of higher temperatures, the fertilizer concentration is lowered to a level of 150 to 180 ppm of nitrogen. The other element concentrations are also reduced, however the ratio between them is maintained. In compound fertilizers, microelements can be supplied as part of the commercial fertilizer components or can be applied separately through the irrigation system. by the plant in two ionic forms: ammonium (NH4+) and nitrate (NO3), both of which are found in commercial fertilizers. In many studies, it was found that a high NH4+ concentration will reduce fruit size, increase the incidence of blossom-end rot (BER) and, in some cases, affect plant growth.According to these findings, it is recommended that the NH4 ammonium ratio in the total nitrogen (N) does not exceed 25% for soil nutrition. 44 Basic fertilization Before planting tomatoes in greenhouses, a soil test should be taken so as to check the amount of potassium and phosphorus in the soil. When the phosphorus level in the upper soil layer is 35 ppm and more (according to the Olsen method), it is not necessary to add phosphorus. When the results of the soil analysis show that the phosphorus level is lower than 35 ppm, about 100 kg/ha of superphosphate should be added in order to increase the phosphorus level by 1 ppm. The required potassium level is 12 ppm CaCl2 or ∆F = 3,200, or 1 meq/L. When the results of the potassium analysis are lower than the required values, potassium chloride should be applied, as recommended in Table 14. Positions of tensiometers and extractors Macroelements (%) Microelements (ppm) N 4.0-5.0 Fe 70-100 P 0.4-0.6 Mn 100-250 K 3.5-6.0 Zn 35-80 Ca 2.0-4.0 CU 5-20 Mg 0.4-0.8 B 30-80 S 0.1-0.15 Table 13. Analysis of element nutrients in tomato plants Table 14. Fertilizing with potassium chloride (kg/ha) according to laboratory test findings Potassium chloride or potassium sulfate (kg/ha) Results according to testing method Soil extract (meq/L) for light soils CaCl2 extract (mg/l) for medium and heavy soils over - 15 10-15 less than 10 Over - 3,200 From -3,400 to -3,300 Less than - 3,400 Over 1.0 0.5-1.0 Less than 0.5 No need to apply 500 1,000 for all soils Cal/mol
  • 50. 45 Recommendation of general nutrition for Daniela type tomatoes Base dressing-Application without soil analysis (1000m2=0.1 ha) Organic compost (processed) 600-800 kg/1000m 2 or organic compost (well prepared) 4-5 m3 /1000 m 2 + 100 kg of 5:11:22 per 1000 m 2 + Magnesium sulfate-50kg/1000 m 2 (especially for light soils) Seasonal nutrition according to growth stages 1. After transplanting till flowering of first cluster Starter fertilizer-N: P2O5:K2O =1:1:1 100-150gm N per day per 1000 m2 2. First cluster until flowering of fourth/fifth cluster Fertilizer-N: P2O5:K2O=1: 0.3-0.5:1.5-2 200-300 gm N per day per 1000 m2 3. Fourth/fifth cluster flowering until first harvest Fertilizer - N: P2O5:K2O =1: 0.3- 0.5: 2 400-600 gm N per day per 1000m2 4. Harvesting period until topping the plants Fertilizer - N: P2O5:K2O =1: 0.3: 2 500-600 gm N per day per 1000 m2 5. Topping the plants until the end of harvest Fertilizer - N: P2O5:K2O = 1: 0: 2 400-200 gm N per day per 1000 m2 Micro-elements Micro-elements should be supplied continuously after transplanting. Use a prepared micro-element mix. Keep 40-50 ppm of Mg in the drip irrigation. Keep 100-120 ppm of Ca in the drip irrigation. Table No.15 describes the influence of fertilizer concentrations and water quantities on the general yield and on the percentage of fruit that is suitable for export. The results show that yield quality and quantity increased significantly when fertilizer concentrations are increased up to 400 ppm (osmotic stress). The same result is achieved when the irrigation water application is reduced to 30% of the evaporation rate (water stress). In both approaches improved quality and a higher percentage of export-quality fruit is accompanied by smaller fruit and a lower general yield level. The information in the table can be used to decide which means and stress method (osmotic or water stress) should be applied to achieve a high quality fruit. Producing quality fruit Quality tomatoes can be produced if a number of irrigation and fertilization principles are adhered to: Adequate potassium and nitrogen ratios, as described above, especially towards the harvest season, help to create a fruit with a long shelf life and a uniform red color. Potassium deficiency results in blotchy ripening, soft fruit and a shorter shelf life. Adequate nitrogen level contributes to a strong growth, high yield and fruit of the right color and size, without sunscald or yellow shoulders. Suitable humidity and water tension in the soil contribute to satisfactory fruit size, quality and shelf life. Extreme changes may damage these properties. Nutrition control and fertilizer monitoring Nutrition control is similar to irrigation control and is based on the knowledge of the contents of the soil solutions. This control method includes an electric conductivity (EC) test of the dripper water by collecting irrigation water during irrigation. The tests show whether the fertilizers are being applied as planned. The soil solution is examined after removing it from the soil with extractors, which are installed in the root zone area at two depths: 20 cm and 40 cm in light soil; and 30 cm and 50 cm in medium-heavy soil. Treatment AII AIII BII BIII CI CII R Accumulated irrigation m3 /ha Accumulated fertilizers (kg/ha) Pan evaporation Coef. Nitrogen concentration in irrigation water ppm Yield per ha Total yield (ton) Yield for export (ton) Export quality fruit (%) Nitrogen Phosphorus Potassium 5,050 12,000 5,700 12,400 2,400 4,900 3,350 390 910 880 1,800 740 1,460 530 70 170 160 330 140 270 500 490 1,140 1,100 2,270 920 1,820 960 0.75 1.60 0.75 1.60 0.30 0.75 0.57 100 100 200 200 400 400 165 165 166 153 166 63 113 100 69 32 83 36 46 74 76 42 19 54 22 73 65 76 Table 15. Effect of different fertilization and irrigation regimes on total production and exportable quantity
  • 51. 46 Iron and/or manganese deficiencies Iron and manganese deficiencies are common in the different growing stages and in all seasons. Extreme iron and manganese deficiencies appear in lime-rich soils and in soils lacking aeration, where flooding and excess water cause lack of oxygen and leach ions from the root zone. The deficiencies are characterized by chlorosis that appears Magnesium deficiency Magnesium deficiency is characterized by yellowing of the mature leaves in the lower and central part of the plant. The veins remain green. Magnesium deficiency is common in autumn and winter, when soil temperatures drop significantly, especially in regions where there is a low level of magnesium in the water. Magnesium deficiency is also common when the EC values in the root zone are high as a result of high concentrations of potassium. on the plant crowns. In extreme situations, it results in necrosis and drying out of the young foliage and degeneration of the plant crowns. Iron deficiency is characterized by a general lightening of the entire leaf, including the veins. In the beginning, signs of deficiency appear close to the leaf base, and quickly spread to the leaf tips. Manganese deficiency is characterized by changes in spots of color on the leaf, which grow and join up to form general chlorosis. Veins remain green in cases of manganese deficiency. Soil treatments If the signs of deficiency are severe, it is recommended to apply one full application of iron chelate (6% Fe): 5-10 kg/ha with two liters of manganese chelate (13% Mn), and to continue with the same materials: 8 g iron chelate and 30 cc manganese chelate for every m3 of water, until symptoms disappear. To prevent deficiency, it is recommended to apply 80 - 100 cc of a commercial microelement compound mix to one m3 of water. The extractors are set once a week, just after the irrigation water for that day has stopped seeping/draining in the soil, and a few hours later, the solution that has accumulated in them is removed. The EC of this solution is tested to ensure that it is not significantly higher than the EC of the dripper water. The nitrogen level in the soil solution is also tested by using a nitrate (NO3) kit. If both of these tests are positive (dripper and extractor solutions produce the same results), it indicates that irrigation and fertilization are satisfactory. A significant difference in the EC and nitrogen levels in the dripper water and extract solution indicates that irrigation and fertilization is unsatisfactory. If the EC and nitrogen levels in the extract are low, application of nutrients should be increased. If the EC and nitrogen levels in the extract are very high compared to the dripper water, the fertilizer concentration in the irrigation water should be reduced. As well as the tests, which are conducted by removing the soil solution with an extractor, the soil should be analyzed in a laboratory test two or three times every season, with the aim of adjusting fertilization to the actual soil condition during the growing season. Acidifying the irrigation water Optimal absorption of phosphorus and microelements takes place in an acidic environment (pH=5.5-6.5). The irrigation water and much of the soils in Israel and in other neighboring countries have a high lime concentration, and bicarbonates are formed when the lime dissolves in the soil. The irrigation and lime in the soil create an alkaline pH of 7-8. This high pH level interferes with the absorption of some of the nutrient elements. In order to improve the absorption of these elements by the root system, the irrigation water can be acidified with phosphoric acid (85%), nitric acid (60%) or sulfuric acid (98%). Phosphoric or nitric acids constitute a source of macro- nutrient elements and this should be taken into account when planning the fertilizer formula. Acidifying irrigation water prevents the formation of calcium sediments in the dripper, which causes gradual clogging and lack of distribution uniformity. It also improves the absorption of nutrient elements. The acids should not be combined with the fertilizer, therefore two fertilizer pumps can be installed at the control head: one to inject the fertilizer, and the other to inject the acid. The acid is injected into the water line about 20-30 cm before the fertilizer is injected. 20 MICRO-ELEMENT DEFICIENCY INTOMATOPLANTS Iron deficiency Manganese deficiency
  • 52. 47 Magnesium deficiency – yellowing between veins Phosphorus deficiency – purple leaves Calcium deficiency - Blossom - end rot Calcium (Ca) is considered to be one of the macroelements that is required by the plants in large quantities, and is present in high concentrations in the cell walls and membranes. In stress conditions, the supply of calcium to the young fruit is irregular, and as a result of this deficiency, the tissue in the blossom end of the tomato collapses, and the damaged tissue turns dark brown. This is known as blossom - end rot and is characteristic in young fruits which are still 30-70% of their final size. Tests show that when the EC level in the soil solution exceeds 3 dS/m-1 and the calcium concentration is lower than 100 ppm, the plant is more susceptible to blossom-end rot. Calcium generally moves through the xylem via the water flow in the transpiration process. However, most of the water which reaches the tomato fruit comes from the phloem system and therefore the quantity of calcium that reaches the fruit is relatively small compared to the quantity that reaches the leaves. The problem may be intensified when there are short stress periods. Since cells and membranes are created in the growing zones of the plants, they may be the first plant parts in which calcium deficiency is apparent. Calcium is an ion that moves with difficulty within the plant and is not transferred from older plant tissue to younger tissue, therefore calcium deficiency is invariably noted in the young plant tissue and especially in growing fruits. In extreme cases of deficiency, damage is caused to the young plant tissue, resulting in browning of young leaf edges or yellowing of the tissue between the veins in the young leaves. For tomato fruit dry matter, calcium concentrations in fruit damaged by blossom-end rot were less than 0.08%, while calcium concentrations in tissues from healthy fruits were between 0.12 and 0.25%. Calcium concentrations in leaves with calcium deficiency symptoms were less than 0.2%, while concentration levels in healthy leaves were between 2 and 4 %. Principal factors that encourage appearance of blossom-end rot 1. Calcium deficiency in the soil or soilless culture 2. Unexpected temporary soil stress 3. Salinity stress as a result of salt accumulation in the root zone 4. Competition with other elements in the soil or substrate 5. Relatively low humidity and hot wind conditions 6. High temperatures accompanied by relatively high humidity 7. Under-developed root system 8. Sensitive varieties: elongated varieties are usually more sensitive to blossom-end rot 9. High levels of ammonium (NH4). Means to control blossom-end rot 1. Sufficient calcium (Ca) supply in the irrigation water 2. Regular irrigation and prevention of water stress 3. Prevention of fertilizer accumulation in the soil or substrate. In these cases, irrigation applications should be sufficient to leach excessive salts. 4. Application of potassium and magnesium, according to plant requirements. High concentrations of these elements in the soil inhibit calcium absorption. 5. Maintenance of proper relative humidity (about 70%) in the greenhouse, especially in autumn and spring 6. Good establishment of the plant and development of a wide and deep root system, which provides the plant with the ability to withstand adverse conditions. 7. Planting of varieties which are tolerant to blossom- end rot 8. Avoidance of excess NH4- in the nutritional formula. It is recommended to increase the magnesium concentration in the water by applying fertilizer, which also contains magnesium or by using special fertilizers, which are injected by another pump when applying fertilizer. The magnesium level in the irrigation water should not be less than 40 - 50 ppm from the beginning of the season. The quantity of fertilizer to be added is determined after a chemical analysis of the water that shows the magnesium concentration. In some studies, it was found that magnesium can also be supplied by spraying the foliage with 2.5% Magnite or 2% Magnisol, both of which are magnesium nitrate. Spraying in hot weather may burn the foliage.
  • 53. 48 Calcium deficiency (BER) Calcium deficiency (BER) Boron deficiency Tomato plants are considered to be tolerant to salinity and are capable of growing and producing commercial yields when grown in saline soils and even when irrigated with saline water. These facts are known in Israel and around the world, and this knowledge is used to establish agro- technical methods to improve the taste and quality of the tomato. However, when salinity is uncontrolled, situations may be created which have a negative influence on both soil and plants, as a result of salt accumulation in the soil. Heavy soil is damaged by the accumulation of sodium which leads to the dispersal of clay particles and the soil becoming brackish. High soil salinity results in defective water absorption by the plant as a result of an increase in the soil solution’s osmotic potential. This leads to a reduction in cell volume, fruit size and yield quantity. In certain situations, when there is a rise of harmful elements in the soil (such as sodium and chlorine), they are absorbed and signs of toxins appear in the foliage. The soil salinity index is electric conductivity (EC), which is measured in units of deciSiemens per meter (dS/m). The EC expresses the conductivity level, which is from all the salts in the solution. Some salts are beneficial elements (such as potassium, phosphorus and nitrogen), which the plant requires and absorbs, and some are harmful elements (such as chlorine and sodium), which are not absorbed by the plant but they can increase the EC and even change soil texture. Soil samples are analyzed in a laboratory for each of the ions required by the plants, in order to learn the specific composition of salts in the soil, and to learn which factors influence the increase of the soils’ EC values. The ions include: phosphorus, nitrogen, potassium, calcium, magnesium, iron, zinc, manganese and copper. The analysis is also conducted on ions that are known to be harmful to plants, such as sodium and chlorine. Main factors that encourage accumulation of salt in the soil: 1. The concentration of salts in the water which is an indication of its quality 2. Types and quality of fertilizers 3. Uncontrolled nutrition- large fertilizer applications 4. Volume and frequency of water application. Improving quality and taste by irrigation with saline water Much research has been conducted in Israel and other countries, and has demonstrated that the irrigation of tomato plants with saline water increases fruit quality as expressed in significant changes in the fruit’s external appearance, which becomes rounder and has a strong red color. The fruit’s taste improves as a result of a sharp increase in the concentration of total soluble solids (TSS), especially regarding the sugar and acid concentration, 21 SOIL SALINITY
  • 54. 49 which together determine the quality of the fruit’s taste. Irrigation of tomatoes with saline water led to a reduction in the yield level by reducing the fruit size, compared to fruit on plants grown with regular fertigation regimes. In principle, irrigation with water that has an EC of 2.5 does not damage the tomato yield. Research and accumulated experience in growing tomatoes in saline water indicate that an EC level of 4.0-6.0 dS/m in irrigation water may result in changes which improve the quality and taste of the tomato fruit, without significant harm to the yield level. Most researches show that the decreased yield is a result of a smaller fruit size and diameter. Good results in yield level were achieved when salinization (increasing salinity) continued for 60 to 75 days, followed by a gradual reduction. In this way a drastic reduction in the yield level was avoided. It was also found that with proper salinization the yield is reduced by about 25-30%, compared with the yield of plants that grow in non-salinized fertigation conditions. Salinization principles for improved fruit quality 1. Irrigation with natural saline water from local wells. 2. Artificial salinization by adding salt solutions: 15 % CaCl2 + 85% NaCl 30% MgCl2 + 30 % CaCl2 + 40% NaCl 3. Salinization after plants have become established and flowers appear in the first inflorescence. 4. Gradual reduction of saline concentration after 60 to 70 days. 5. Irrigation with large water applications at the end of the salinization process to leach salt which accumulates in the root zone. 6. Monitoring and follow-up to prevent accumulation of surplus salts in the soil or growing medium, by using extractors during the salinization period to analyze and control the soil solution. When irrigating with saline water, steps should be taken to avoid stress caused by a water deficit in the soil, and the water tension in the root zone should be low throughout the salinization period. A combination of water deficit and saline conditions leads to a significant decline in the yield level, and sudden water deficiency increases appearance of blossom-end rot. The efficiency of irrigation with saline water increases in sandy soil or soil-less culture. In these conditions, the root zone can be easily flushed when there is excess accumulation of salts. On the other hand, in soils with a high level of clay, there is a risk of salt accumulation, especially with salts containing sodium (Na). Sodium may cause damage to the soil structure and texture and is very difficult to flush out in clay soils. Therefore, salinization treatments to improve tomato quality are recommended only when tomatoes are grown in light sandy soil or in soilless culture. Salinization of irrigation water Increasing EC by adding Sodium Chloride and Calcium Chloride in distilled water gr./l
  • 55. 22 50 The following graph describes the response of fruit size to saline water during the season (plant age is in days from planting). The key indicates the number of salinization days (S) and salt leaching at the end of the period (+L,-L). Response of the fruit size to salt Vegetable production in substrates has been used for many years. In Israel, tomato production in substrates is growing steadily and covers close to 70 hectares. Growing GROWING TOMATOES IN SUBSTRATES (SOILLESSCULTURE) in substrates in greenhouses is suitable for intensive crops and enables production in all geographical conditions. The advantages of this method are: good control and monitoring of nutrients and irrigation, early ripening, improved fruit quality, quick transition from one crop to another and reduced risk of soil-borne diseases. Soilless culture can be sanitized with several different methods, which are more effective in substrates than in soil. These methods include soil solarization, which is highly effective, and application of Metham Sodium substances. Growing in soilless culture requires extensive professional knowledge in fertigation methods, as well as skills in operating automated control and command systems. Growing media: (Substrates): Growing media which is suitable for tomato production has the capacity to store a sufficient quantity of water, air and nutrient elements that are available to the plant and also has a high drainage capacity. In suitable growing media, excess salts that accumulate in the media and cause damage to plants can be rapidly removed. Good growing media should also be lightweight with a texture that remains stable in the long term. Suitable growing media: Mineral media Volcanic gravel or rock (tuff) Rockwool Perlite Organic media Peat Compost Coconut coir Mineral and organic media mixtures Tuff and compost Perlite and compost Peat or coconut coir with Styrofoam beads Tuff media packed in polypropylene containers In experiments and observations that were conducted on tomato production in greenhouses, it was found that the substrates that are most suitable for tomato production are Perlite 2, Tuff rock M 0.8 or a mixture of tuff or Perlite with organic media. The mixed growing media have a high water retention capacity and a relatively high buffer capacity. This provides tolerance to extreme changes in the supply Burn folaige by high salinity in the soil
  • 56. 51 Nutrient Film Technique (NFT) The Nutrient Film Technique is an additional method used for growing tomatoes under soilless conditions. NFT was developed in the 1970s in the British Isles, the principle being that the roots of the plants grow in a shallow nutrient solution that is kept circulating continuously. The basic features of NFT are based on: Growing gullies that are made out of plastic film laid on a suitable slope A tank containing nutrient solution A catchment tank at the lowest point of the greenhouse A pump that delivers the solution to the upper ends of the gullies A monitoring and control system to maintain the nutrient solution of EC and pH The NTF system is susceptible to damage if there is a sudden interruption in the flow of the nutrient solution to the plants, especially on sunny days. Therefore, it is essential to make adequate provisions for electrical and/or mechanical failure by ensuring safety devices, keeping a spare pump, a stand-by generator and an alarm system. Growing containers: Size and growing media Types of containers 1. Styrofoam containers, with a volume of 70 liters and internal dimensions of 115 x 40 x 15 cm. About 4,000 containers are used per hectare. 2. Black PE buckets or bags, with a volume of 10 liters for one plant. About 22,000 - 24,000 buckets or bags are used per hectare. 3. Black PE bags, with a volume of 20 liters, which are up to 25 cm high, and are suitable for growing two plants per bag. About 11,000 - 12,000 bags are used per hectare. 4. Polypropylene and polycarbonate growing troughs, of different sizes. Dimensions of polypropylene and polycarbonate troughs Height: 17cm Base width: 40 -50cm Length: According to the slope in the greenhouse and the drainage holes of the trough. If the slope is sharp and the trough has no holes, it is recommended to use short troughs of 10 to 15 m. If the troughs have drainage holes at the sides, troughs of up to 30 m or more can be used. Types of growing media according to container type 1. In large containers (Styrofoam, polypropylene, and polycarbonate troughs): unsifted tuff 0-8 M, Perlite, or an organic mixture. Media volume: 300 – 500 m3/ha. The compost that is used in the mixture is composed of mule manure and grape dregs at a ratio of 1:1 re: to volume. Growing tomatoes in rockwool substrate Table 16. Physical properties of various substrates * Natural tuff moistness Property Air capacity at 10 cm tension Hermonit tuff 0.8 M Agriman Cocount Salit rockwool Perlite 2 for agricultural use Optimal Values Calculated porosity (%) Measured Porosity (%) A WP-Available water capacity (%) (10-50cm) WBC-Water Buffering capacity (%) 50-100 cm) LRAW-Less readily available water (%) (100 cm and above) Bulk density (kg/m3 )* 20-6 55-65 43-46 12-15 2.5-3.5 17-22 1,200- 1,300 30-33 85-93 20-24 2-2.5 30-34 80-90 23 80-85 55 0.2 6 90-110 24 85-90 83 21 33 60-80 5 20-30 20-30 4-10 _85+ of water and nutrient elements to the plants which may occur during the growing process. On the other hand, the use of mineral growing media without any added organic substance, such as rockwool, Perlite or tuff, requires meticulous control of the fertigation system in order to prevent extreme changes in the supply of water and nutrient elements. Research shows that the addition of organic substances to the substrate freguently reduces the incidence of soil-born diseases.
  • 57. 52 2. In small containers (bags or buckets): A mixture of sifted Tuff B 0-8 or Perlite (70%) with 30% compost. The growing media volume is about 250 – 300 m3/ha. 3. Rockwool packed with plastic cover, no need for containers. Comments Varieties that are sensitive to blossom-end rot should be grown in large containers. It is recommended to paint the exterior of the black buckets or bags white to prevent the growing medium and root zone from over heating. Drainage of containers Drainage of excess water from the growing containers is necessary to ensure healthy plants. Water that accumulates in containers with no drainage reduces the oxygen level in the growing medium. This damages the root system’s ability to absorb nutrient elements, especially microelements and creates chemical compounds that are harmful to the plants. A good example can occur when nitrates (NO3) encounter lack of aeration and are converted to nitrites (NO2) which is toxic to the plants. In addition, when there is insufficient aeration in the growing medium, the risks of developing root diseases are higher. In order to drain the containers and remove the surplus water, steps should be taken to ensure that the water drains off easily from the outlets in these containers. Styrofoam containers should be perforated before planting, with 3-4 drainage holes on each side, totaling 6 – 8 drainage outlets for each unit. There are two methods for draining polypropylene containers: 1. Drainage along the length of the growing container: A drain, which is attached to a collection pipe perpendicular to the crop rows, is installed at the end of the unit (the crop unit is 10-15m in length). 2. Drainage on the sides of the containers: There is an outlet every 30-40cm. Options for this drainage method include: Side drainage to two gravel ditches, which are on either side of the container Side drainage to a central gravel ditch under the containers In small containers, buckets or bags, 4 - 5 holes should be punched in the lower part of the container (not in the base). It is recommended to punch holes around the entire container diameter. The diameter of the holes should be 8-10 mm. Advantages: Polypropylene containers are heat resistant and are suitable for steam sterilization, unlike Styrofoam containers which are not suitable for this, as they are damaged at temperatures around 80ºC. Covering the containers The containers are separated from the soil by a black 0.15-0.2 mm PE sheet which is spread over the soil. Before spreading out the PE sheet, the area is leveled and a suitable slope is created (0.8 – 1.0 percent), which allows excess water to flow out of the greenhouse. Water that stagnates in the greenhouse constitutes a source of disease. The Styrofoam containers are wrapped with black-white PE film (white on the outside), which is 1.3 m wide. This creates a drainage canal to carry the drainage water along the row. The PE sheet is spread out before the containers are placed on the ground. Holes are punched in the upper side of the PE sheet as preparation for planting the seedlings. PE sheets are used as a covering or as a means to carry drainage water along the row. Polypropylene sheets, which are thinner, can also be used for this purpose. This material is usually durable for many years. Containers filled with agricultural Perlite Preparation for soilless culture: polypropylene containers
  • 58. 53 Preparation for soilless culture
  • 59. 54 Rinsingthegrowingmediabeforeplanting New organic growing media mix: After the containers are filled and placed in the growing area, they are irrigated to leach salts from the growing media. After rinsing, the EC level in the drainage water should be lower than 1.5 dS/m. Old growing media: Experience shows that there is a significant accumulation of salts at the end of the growing season. This may cause serious damage to the new crop and therefore the growing media should be rinsed in the same way as new growing media. Enriching new tuff with phosphorus Since the new tuff absorbs most of the phosphorus in the irrigation water, restricting phosphorus absorption by the plant, it is recommended to enrich the tuff with this element before planting. The tuff is enriched with 100-190 cc of phosphoric acid per 1 m3 of water (according to the bicarbonate content in the water). During the acidifying process, acids cause a titration of bicarbonate in the water. It is usually possible to titrate 1 ppm of bicarbonate by adding 1 cc of phosphoric acid to 1 m3 of water. About 50 ppm of bicarbonate should be maintained in the water during the acidification process to prevent a drastic decline in the pH. For example, 50 cc of phosphoric acid for each 1 m3 of water is added to water which contains 100 ppm of bicarbonate while 100 cc of phosphoric acid for each 1 m3 of water is added to water which contains 150 ppm of bicarbonate. The phosphoric acid is applied with a heavy irrigation session, while ensuring proper drainage and wetting of the growing media. When the phosphoric acid is injected into the irrigation water, the pH level of the dripper water is tested to ensure that it does not drop below 5.5. Irrigation equipment The irrigation equipment is chosen according to the type of container. One dripper with 2-4 l/h discharge is used for each plant in small containers (bags or buckets). This allows effective salt leaching. In containers that are arranged in a row, such as Styrofoam or polypropylene containers, two drip laterals with 1-2 l/h drippers are used, with 15-20 cm between drippers. Low-volume drippers are recommended. Irrigation regime The irrigation regime during the growing season is influenced by a number of factors. Main factors: 1. The plant’s daily water consumption is influenced by the different growing stages, the season, region and climatic conditions. 2. Volume of irrigation is influenced by daily consumption and drainage rate. An adequate quantity is required to prevent accumulation of salts - especially sodium and chlorides - in the growing media. Table 17. Recommended drainage rate according to Chloride concentration in the irrigation water Chloride concentration (mg/l) Below 150 150-250 250-300 Over 300 Drainage rate (%) 20-25 30-40 40-50 50-60 3. Irrigation frequency is influenced by the plant’s requirements and the percentage of water that is available to the plant. This depends on the type, volume and age of the growing media. Growing media that is composed of an organic matter mix usually has a high water retention capacity and accordingly the water volume that is available for the plant is relatively high. On the other hand, the water volume that is available for the plant is lower in growing media with a low water retention capacity. The age of the growing media also influences the water retention capacity. For example, tuff that has been used several times has a greater volume of small aggregates in the growing media. This leads to a higher water retention capacity, resulting in an increase in the available water capacity. The growing media volume has a decisive influence on determining irrigation frequency. In a small volume of growing media, irrigation frequency is high, and in a large volume of growing media, irrigation frequency is low. This approach is relevant to all types of growing media. The irrigation regime and irrigation management for crops grown in soilless culture are determined on the basis of information on the plant’s requirements, irrigation frequency and size of irrigation application. Collection of drainage and irrigation water
  • 60. 55 Nutrition Compound (NPK) fertilizers can be used, or fertilizer solution can be prepared by mixing a number of different types of fertilizers. One or two tanks are used, with a size that is compatible with the size of the area. The use of more than one tank enables application of fertilizers that cannot be mixed due to sedimentation or disintegration of some of the nutrient elements. In addition, the use of more than one tank allows nutrient elements, such as calcium, manganese and sulfur, to be added to the irrigation water according to the crop requirements, and enables control of the pH level in the growing media through use of acids or by changing the ammonia-nitrate ratio in the fertilizer solution. The use of more than one tank requires a number of pumps (one pump per tank) which operate simultaneously and inject fertilizer solution into the irrigation system. In fertilization which is applied with one tank and one pump, compound fertilizers or fertilizer mixtures – such as ammonium sulfate, phosphoric acid and potassium – can be used. In soilless culture it is important to acidify the irrigation water in order to prevent sedimentation of salts and clogging of drippers, and in order to stabilize the pH level in the growing media. Table 18. Fertilizer composition recommended in two tanks (one pump per tank) Concentration of required microelements in the irrigation water is expressed in ppm Fe: 1.2-1.4; Mn: 0.6-0.7; Zn: 0.3-0.4; Cu: 0.1-0.2; Mo: 0.05-0.1; B: 0.25-0.3 Comments: When mixing fertilizers independently, 120-150 cc microelement mix and 5 g iron chelate (6%) are added for every m3 of water. When fertilizing with compound fertilizers (NPK), it is recommended to enrich them with microelement solution (6%) and magnesium (0.5%). It is recommended to prepare a container to collect dripper water by connecting a dripper and tube to the irrigation pipe. The dripper water is collected in a closed container for chemical analysis and the results are compared with those of the drainage water. Ammonium-nitrate ratio: The quantity of ammonium constitutes about 10-20 % of the total nitrogen in the fertilizer solution (according to growing season). The calcium and magnesium concentration in the fertilizer solution is calculated after determining the level of these elements in the tap water. Irrigation and fertilization control Growing tomatoes in soilless culture requires strict irrigation and fertilization control throughout the growing stages: It is recommended to test pH, EC, nitrate and chlorine frequently, using field kits. Once a month, pH, EC, NO3, P, K, Ca, Mg, CI and B should be tested in a laboratory. pH: The pH level in the dripper water should be 6.0-6.5. Acid can be used to bring the pH level down to these values. The bicarbonate content in the water is determined and then acid quantities are calculated. EC: The electric conductivity of the dripper water depends on the EC of the tap water plus the fertilizer solution. The difference between the EC of the drainage water and the EC of the dripper water should not exceed 0.4-0.5 dS/m (according to water quality). If the drainage water EC exceeds these values, the chloride level in the drainage water from the growing media should be tested. If the chloride level exceeds the chloride level in the tap water by 50-100 mg/l (but the nitrate level is satisfactory), it should be rinsed with water, without reducing the fertilizer concentration. If the chloride level is satisfactory, but the nitrate level in the drainage water is much higher than in the dripper water, it should be flushed with water containing half of the fertilizer concentration. The chlorine test is also important to determine the size of the irrigation application. Nitrate (NO3) test: The nitrate level in the drainage water should be about 500-850 ppm. The nitrate concentration in the dripper water varies according to the crop cycle and growing season. If the Litmus paper test shows concentration exceeds 500 ppm (red dark), the solution should be diluted with distilled water at a ratio of 1:1, and the result should be multiplied by two. It is recommended to measure the daily quantity of drainage water to determine the fertigation regime. If drainage is higher than recommended (30%), the water application is reduced, and if drainage is lower than Table 19. Concentration of elements in irrigation water (dripper) Tank A Calcium nitrate (powder or liquid) Tank B Magnesium nitrate (if required) Potassium nitrate (half the quantity) Phosphoric acid Potassium nitrate (half the quantity) Nitric acid Microelement mix (with Boron, if required) Sulfuric acid (if required) Chelate iron Ammonium sulfate Liquid ammonium (if required) Stage of plant growth Planting and establishment g/m3 (ppm) 100-120 N 40-50 P 150-180 K 100-120 Ca 40-50 Mg Flowering in first inflorescence until flowering and fruit set in 4-5 inflorescences 150-180 40-50 250-350 100-120 40-50 Flowering and fruit set in 4-5 inflorescences and so on and picking period 180-200 40-50 300-400 100-120 50-60 Hot season (spring-summer) 150-180 35-40 250-300 100-120 40-50
  • 61. 56 30%, the number of irrigation sessions and total daily application is increased. The dripper and drainage water tests are conducted with reliable field kits, which are calibrated and adjusted to the conventional values in qualified laboratories. Ensuring reserve water Reserve water tanks are required when growing crops in soilless culture. These tanks should have a volume of about 100-150 m3 per hectare, which is sufficient irrigation water for one or two days. This will ensure a continuous water supply if there is a disruption in the regular water supply or a malfunction in the central irrigation system. Field kits for chemical tests A number of tests, which provide the grower with basic data, can be easily conducted in field conditions. These tests can be used to compare solutions that are collected from drainage or pumps with dripper water. The kits that are chosen should be reliable, easy to use and inexpensive. The following kits can be used in field conditions: 1. EC meter (digital): Requires daily calibration; the electrode should be rinsed after use with a solution that has a known EC. 2. Kit for testing pH: Electric pH meter (digital): Requires daily calibration; is sensitive due to accumulation of salts on the electrode. Drops for testing pH: Usually produce reliable results. Sticks for testing pH: Usually produce reliable results. Influence of pH on availability of essential nutrients in soil Curling of top leaves – surplus fertilizer
  • 62. 57 3. Nitrate and nitrite kit: The litmus paper has two bands. The upper checks nitrite (NO2) and the lower checks nitrate (N03). When there is no nitrite, the stripe remains white, however, when there is nitrite, the stripe turns pink or red. Nitrite is toxic and damages the root system, and indicates a lack of oxygen in the growing media. The nitrate kit tests up to 500 ppm. If the color is too dark, the solutions should be diluted with distilled water with a ratio of 1:1, and the result should be doubled. Comment: The nitrate kit tests nitrate only and does not provide data for all the Nitrogen in the solution. 4. Chloride kit: This is based on drops and titration. It supplies data on the Chloride concentration in the solution that is being tested. Using the information that is received, it is possible to analyze irrigation procedures especially the size of the irrigation application. In greenhouse tomato production, where crops are grown in soilless culture, a significant amount of drainage water runs off from the greenhouse to the environment. This constitutes an environmental hazard for various reasons, some of which are listed below: Environmental pollution and constant wet soil around the greenhouse. Growth of unwanted weeds in the different seasons, which serve as a host for diseases and pests. Penetration of nitrates and other toxins into the soil that can pollute the ground water. A high percentage of drainage water runs off from the growing media after each irrigation application. This constitutes a waste of water which is valuable, as it contains a high concentration of fertilizers. The drainage percentage is influenced by the irrigation frequency and initial water quality (chloride concentration in water). This water contains a high level of elements, which is similar to the concentration of microelements in the dripper water. The high level of elements in the drainage water increases the economic value of the water, and thus by collecting the excess water in tanks, it can be reused for irrigation. The most efficient system for recycling drainage water is a closed recycling system. This system collects the drainage water and returns it to the crop after a sterilizing process which eliminates pathogens such as fungi, bacteria and viruses. When planning a closed recycling system, the following Field kits for chemical tests 23 RECYCLING DRAINAGE WATER Diagram of a recycling system
  • 63. 58 Containers for collecting drainage water and reservoirs Sterilizing drainage water Methods for sterilizing drainage water: UV radiation: This system destroys fungi, bacteria and some viruses. The method requires meticulous filtration of the drainage water to increase its clarity before sterilizing with the UV tube. Filtration by a biological filter: This method is efficient and is recommended for selective sterilization of pathogens, especially fungi. Chlorination: Active chlorine is added to the drainage water. The chlorine concentration is suitable for destroying the pathogens and does not damage the plants. The method is already being applied in commercial farms. Thermal sterilization: In this method, the drainage water is heated to between 65ºC and 85ºC for three minutes. This method is efficient for destruction of most pathogens, fungi, bacteria and viruses. Ventilation in greenhouses Ventilation in greenhouses for tomato production has many purposes, the main ones being: 1. To remove humidity 2. To remove excess heat 3. For CO2 enrichment 4. To remove noxious gases Ventilation to remove humidity Plants grown in closed structures emit great amounts of water vapor into the atmosphere, and consequently the humidity rises to high levels. When the external temperature of the greenhouse is lower than the internal temperature (usually at night), the plants cool rapidly and condensation forms on the foliage. Moreover, water vapor accumulates on the internal surface of the structure’s covering. If the plastic film does not have anti-drip additives, the accumulated moisture drips back onto the plants. High relative humidity also creates conditions for development of various fungal and bacterial leaf and fruit diseases. In high humidity, the propagation and ripening processes are disrupted, stamens do not open, pollen is not released, and the quality of the fruit is damaged. In winter, it is often necessary to ventilate the greenhouse to remove excess humidity, even though this causes low temperature. Ventilation instructions 1. In non-heated greenhouses, it is recommended to have narrow openings along opposite sides of the greenhouse at night. On nights when frost is expected, the sides should be closed down if thermal plastic film (IR) is used, however the openings should not be closed if regular film is used. 2. In heated greenhouses that do not have ventilation systems, it is recommended to remove humid air by opening two opposite sides of the greenhouse during the evening hours and in the early morning, while increasing the heating. 3. In heated greenhouses, with ventilation system fans, the fans should be operated for 1-2 minutes every 20-30 minutes (20 fans per hectare). The operation and regulation of ventilation depends on the amount of water vapor emitted by the plants and the humidity level inside the greenhouse. 4. If there is a climate-control system, the humidity control should be based on the combination of air exchange and heating manipulation. Ventilation to remove excess heat On clear sunny days, temperatures inside a closed greenhouse may become too high and could damage the plants, encourage development of diseases and pest infestation, and harm the proper development of the plants. Exchanging the air inside the greenhouse with outside 24 GREENHOUSE VENTILATION basic needs should be taken into account: Preparation of infrastructure to collect the drainage water and rainfall, and if necessary improve the tap water. The infrastructure should include a pipe system, reservoirs and pumps. Dilution of the drainage water with tap water or rain water to reduce brackishness in the drainage water. Filtration and disinfection of the drainage water with a system that takes into account the sensitivity of the plants to pathogens that are transferred in the drainage water. Control system to monitor fertigation and to determine the EC and pH level and the concentration of nutrients required by the plants. In a closed recycling system, chemical testing should be constantly performed, to ascertain the quantity of elements and for pathological control, to ensure the efficiency of the drainage water’s sterilization system.
  • 64. 59 air helps regulate the temperatures, especially when the external temperature is lower than the internal temperature. Excess heat can be removed in the following ways: 1. In winter, it is sufficient to operate twenty 48” - 50” extractor fans for each hectare to remove excess heat and humidity. The fans are operated by a regulator set to the required temperature of 26º-28ºC. The curtain on the side of the greenhouse where the fans are installed remains closed while the curtain on the opposite side is opened to a height of 30 cm, allowing fresh air to enter the greenhouse. 2. In greenhouses without fans, the curtains should be opened in accordance with outside wind velocity and direction. The opening on the side facing the wind should be narrow, while the opposite side should be opened to its maximum. In principle, curtains should be left open as much as possible. 3. During spring and summer, when the outside air is hot, it is difficult to maintain the required temperatures inside the greenhouse. Every means available to the grower, such as opening side curtains and roof windows, and operating extraction and circulation fans, should be used. When the temperature rises to high values, one of the shading methods described in the Shading chapter can be used to reduce the heat load. Ventilation for passive CO2 enrichment All ventilation methods result in passive CO2 enrichment in the greenhouses. In closed structures, the CO2 concentration in the greenhouse air and plant environment Greenhouses with roof vents, passive ventilation As stated in the chapter dealing with climate, tomato plants require precise temperatures. When the temperature drops below a certain minimum, tomato plants are damaged considerably, resulting in inferior yields and quality. Experiments and observations carried out at experimental stations and tomato farms show that optimum yields and desired quality are obtained in Israel when the minimum temperature is increased to 12º-14ºC. In countries with low day temperatures, more night heating is usually required. Main advantages of heating tomato greenhouses: 1. Regulated growth and development 2. Good plant fertility and fruit set 3. Efficient absorption of nutrients by plants 4. Improved quality of fruit color and shape 5. Continuous and reliable product supply to the market and for export 6. Reduced use of pesticides 25 GREENHOUSE HEATING Frost - damage to foliage Frost - damage to fruit and foliage is drastically reduced to 180-200 ppm, compared to the concentration outside which is 320-340 ppm. Air replacement changes the CO2 concentration in the greenhouse and increases the concentration to the same level as on the outside. These ventilation methods allow the plants to function normally, without any damage to the photosynthesis process or to the yield and fruit quality. Greenhouse with fans, active ventilation
  • 65. Heat transmission via hot water pipesCirculation of hot air via plastic sleeves 60 rows, to provide better circulation of hot air throughout the greenhouse. The heater should be placed on a raised concrete platform to prevent corrosion and other damage to its casing. The wind direction and velocity, as well as the location of the extractor fans and wind shear, should be taken into account when positioning the heater. The heater booth should have a door to the outside, allowing easy access without the need to pass through the greenhouse. A light and electricity socket should be installed in the booth for use at night. 3. Control regulators should be installed in a waterproof box. Regulator sensors are placed in ventilated containers that protect the measuring equipment from dripping water and direct sunlight. The sensors should be installed where they can read the temperature required in the greenhouse. 4. A system of plastic sleeves for heating with hot air is placed along the floor to distribute hot air. The sleeves have holes all along the length. The holes are not spaced uniformly - they are closer together at the end farthest from the heater and become further apart closer to heater. The diameter of the air circulation sleeves is usually 23 - 25 cm. 5. An external fuel tank should be positioned close to the greenhouse, in accordance with safety regulations and with easy access for refilling. Heaters require regular maintenance and periodic services to ensure that they are in efficient working condition. When the greenhouse is completely sealed and a thermal screen is used efficiently, the required heat output will be 20 -30% lower. Heating methods There are three main methods for heating greenhouses: 1. Heating with hot air: Hot air circulates through perforated plastic sleeves that are placed in the paths between the plant rows or between row pairs. 2. Heating with hot water: Heat transmitted by hot water flows through a system of metal pipes that are positioned along the plant beds or in the paths between the rows. These are also used for moving and operating equipment and as an accessory for greenhouse treatments. 3. Combination of the two systems: hot water system and distribution of heat through heat exchange using sleeves. Positioning and operating heaters in tomato greenhouses: 1. Even when heating the greenhouse, heat is lost to the ambient. To reduce heat loss and minimize heating costs, ensure that the curtains, windows and entrances are well sealed. 2. A hot air heater is designed to draw in air, heat it and discharge the heated air back into the greenhouse atmosphere. The heater’s kcal per hour output is selected according to the temperature (∆T) difference between the prevalent minimum temperature and the required temperature. If the outside temperature often drops to 4ºC, the heater required to raise the temperature to 12ºC should be able to provide the 8ºC difference per 0.1 hectare. About 10,000 kcal/h are required to raise the temperature by 1ºC in a 0.1 hectare greenhouse. Therefore an 180,000 kcal/h heater would be suitable for heating a 0.2 hectare tomato greenhouse. An air heater that heats and circulates air throughout the greenhouse should be installed inside the greenhouse or in a special booth adjoining it. The booth, which is closed from the outside and open from the inside, should be attached to the side of the greenhouse. The heater should be centered on the side of the greenhouse, opposite the pathway at the end of the
  • 66. 61 26 CO2 ENRICHMENT FORTOMATOES The photosynthetic process: CO2 + H2O + light } C6Hl2O6 + O2 CO2 is considered to be one of the most important compounds in plant life. During photosynthesis, plants utilize the CO2 from the atmosphere in order to produce sugars. The concentration of CO2 in fresh air is about 330 ppm. When the greenhouse is closed, the plants use the CO2 in the greenhouse for photosynthesis. This results in a drop of the CO2 concentration the greenhouse air. In addition to ventilation for the removal of heat and humidity, CO2 enrichment ventilation is introduced to restore the greenhouse CO2 concentration to fresh air levels. Research shows that the introduction of CO2 into the greenhouse atmosphere greatly increases the vegetative growth of many plants, including tomatoes. Results of studies in Israel indicate a positive response to CO2 enrichment in greenhouse tomatoes grown during the winter and spring months, with yield increases of 8-12%. Financially, this increase does not justify the required investment and running costs. The relatively low yield increase stems from the fact that in Israel, where temperatures rise to extreme levels even in winter and require ventilation and opening of curtains, CO2 enrichment, which is performed in closed greenhouses to prevent loss of gas, is applied for relatively short periods. On the other hand, in countries further north, such as Holland, France and Belgium, where the climatic conditions enable more hours of enrichment during the day, CO2 enrichment in tomato greenhouses is found to have significant advantages and financial justification. Therefore many greenhouses in these countries incorporate CO2 enrichment systems to improve yield and quality. The recommended enrichment level is 700-1,000 ppm, and the conventional enrichment level is 900-1,000 ppm. Ethylene (C2H4) is a colorless and odorless gas which acts as a hormone even in low concentrations. It serves as a growth regulator and constitutes a positive factor by encouraging seed germination, root development and fruit ripening. In high concentrations, ethylene is harmful to plants. The tomato plant is considered to be very sensitive to ethylene, and it serves as an indicator for the presence of the gas. Tomato plants are damaged by ethylene at concentrations of 0.01-0.05 ppm. The symptoms and damage are expressed as deformation of leaves and flowers. The leaves curl downwards and become yellow, growth is stunted and flowers abscise, especially those which have not started to develop as fruit. Since it is not possible to discover the ethylene in the greenhouse air in advance, increased ethylene concentration is indicated by damage to plants. There are different reasons for increased ethylene levels and these include the release of ethylene by ripening or rotting fruit. However, the most common reason is a faulty heating system that produces ethylene as a by-product of poor combustion. The most common cases of ethylene damage were observed when there was uncontrolled use of liquid CO2 tanks used for CO2 enrichment. The heating system in the greenhouse should be checked regularly and there should be proper ventilation to remove toxic gases before they accumulate to harmful levels. 27 ETHYLENE DAMAGE Photosynthesis
  • 67. Disappearance of growing crown When indeterminate plants stop growing for unknown reasons, an inflorescence or leaf appears at the crown, similar to that at the end of growth in determinate varieties. This is common in fields where the plants have dense vegetation, a thick stem and large leaves, as a result of uncontrolled irrigation and fertilization. It appears in different seasons and in most commercial varieties. In general, disappearance of crown occurs following 5-6 normal inflorescences in the plant, and it appears in only a small percentage of the entire crop. In certain cases, termination is complete, while in other cases a new secondary branch grows to replace the original crown. When disappearance of growing crown is encountered and the determinate plant stops growing, a secondary stem should be developed to replace the main stem, or a secondary stem should be allowed to grow on an adjacent plant, to compensate for the plant which has stopped growing. 62 Leaf roll Plants with leaf roll have a lower photosynthetic and transpiration rate, which may result in a significant reduction in yield. Leaf roll is the plant’s response to extreme stress conditions, such as continuous low or high temperature. In harsh conditions, the leaves curl inwards and take on a shape of deep, half-closed teaspoons. The curled leaves become brittle and fragile. When leaf roll is more severe, the fruit is exposed to the extreme climatic conditions and quality is damaged by susceptibility to fruit cracking, different levels of sunburn and even damage to their firmness. The curled leaves maintain full turgidity and do not wither. Different varieties have different levels of sensitivity to leaf roll. These differences are also expressed in less extreme conditions. Leaf roll becomes more severe when the plant rows are east-west. There is a greater incidence of this disorder on the southern side of the rows. Planting in north-south rows significantly decreases incidence of leaf roll. Curled leaves, low temperature Stopped growth without renewal of secondary branches Development of a secondary branch following end of growth Curled leaves, direct radiation 28 GROWTH AND FRUIT DISORDERS
  • 68. 63 Cracks in tomatoes There are three types of cracks in tomato fruit: 1. Radial cracks: cracks that develop from the calyx towards the tip of the fruit 2. Concentric cracks: cracks that partially or completely encircle the calyx 3. Micro cracks: minute cracks that develop around the shoulders of the fruit and are usually not uniform in appearance or quantity Micro cracks Concentric and Radial cracks Concentric cracks The main causes of fruit cracking are: 1. Fluctuation in soil moisture, which causes concentric cracking. 2. Wet vegetation, usually by rain in open fields. 3. Extreme differences between day and night temperatures, which create conditions for the expansion and contraction of the cells in the fruit. 4. High atmospheric humidity that limits evaporation through the foliage and creates water stress, causing cracks. 5. Tomatoes that are exposed to direct sunrays and lack foliage cover. Generally the higher clusters, which are close to the support wires, are especially affected by the extreme temperature differences. 6. High sugar concentrations and general soluble solids in fruits generate lower osmotic potential in the fruit than in other parts of the plant, encouraging flow of water into the fruit and thus forming cracks. This is very common in cherry tomatoes. 7. Old plants and plants with sparse vegetation, small, damaged and defective leaves, have limited evaporation through the foliage and this can result in cracking due to excess water reaching the fruit. 8. Strong removal of leaves results in reduced evaporation and lack of fruit cover, which increases cracking due to root pressure. 9. Low levels of nutrients, especially of potassium (K) and calcium (Ca), which are essential for building and strengthening cell walls. 10. Early morning condensation on fruit, when the fruit temperature is lower than the air temperature, particularly encourages micro cracking. Cracks on all the fruit of the cluster
  • 69. 64 Means to reduce cracking on tomato fruit 1. Extreme soil dryness followed by a large volume of irrigation causes fruit cracking. Therefore, it is important to follow a regular irrigation routine and maintain a stable soil moisture level. 2. In winter when temperatures are low, days are short and plants are not in the best condition, it is necessary to irrigate with very small amounts of water to prevent accumulation of excess moisture that might not be absorbed by the plants due to climatic conditions and limited growth. On the other hand, the excess moisture could be absorbed by the roots, which creates pressure on the fruit and causes cracks. 3. Leaves should not be removed from plants, especially in winter, to increase the vegetative evaporation surface and thereby reduce water stress on fruit. 4. Suitable greenhouse ventilation is required to remove excess humidity from around the foliage and fruit. Damp fruit absorbs the condensation, which results in fruit cracking. 5. New and continuous growth and healthy foliage should be encouraged, to promote a continuous transpiration stream and evaporation of water absorbed by the roots. 6. Plant protection, to maintain healthy plants. Damage caused by mildew, leaf mold and other diseases significantly reduces the foliage evaporation surfaces and causes over-exposure of fruit, which encourages cracks. 7. Fertilization with Calcium (Ca): Calcium should be applied, and its availability to and absorption by plants should be ensured, without creating competition with various nutrients in the soil or bedding material. The recommended concentration is 100-120 ppm. 8. Fertilization with magnesium (Mg): In winter when the temperatures are low, magnesium is more difficult to absorb, causing deficiencies in foliage, especially yellowing between the veins. This reduces evaporation through the leaves, causing water stress on the fruit and increasing cracking. Therefore, during this season the Mg concentration should be increased to 50-60 ppm (including the initial concentration in water). 9. Because a large amount of fruit cracks after being picked, cherry tomatoes should be left in crates in the packing shed for at least one day to ensure that the fruit that cracks during this period can then be eliminated during the grading and packing process. Puffiness in tomato fruit The formation of a gap between the fruit wall and the carpel seed pulp is known as fruit puffiness or hollowness. Hollow tomato fruit lack firmness and have a short shelf-life. They rot quickly and their shape is not characteristic of the variety. Factors encouraging puffiness in tomato fruit 1. Excessive use of Nitrogen when applying fertilizers: prevalent during all seasons. 2. Excessive use of fruit-set hormones: prevalent in fruit treated with hormones. 3. Lack of sunlight: widespread in spring, and especially in winter fruit set (short, cloudy and cold days). 4. Genetic susceptibility: certain varieties are especially susceptible to puffiness, while others are relatively tolerant. Hollowness, Excess of hormones Triangular hollow fruit – internal view Triangular hollow fruit – external view
  • 70. 65 Control of puffiness 1. Controlled fertigation and creation of slight stress to prevent unbalanced growth. 2. Careful use of fruit-set growth hormones. 3. Increase the sunlight in the greenhouse and between plants by: a. Cleaning roofs especially in autumn and winter and whenever they are covered with dust. b. Arranging the support system to allow sunrays to penetrate between the double rows, by maintaining a distance of 60-70 cm between the horizontal support wires. 4. Prevention of overcrowding of plants in the rows. 5. Planting of varieties that are less susceptible to puffiness. Blotchy ripening Blotchy ripening in tomatoes appears as lack of color in certain areas of the fruit. The blotches are not uniform in shape or size and often run into one another, spreading over a large area of the fruit surface. These blotchy areas do not turn red, but tend to remain green with brown spots. The fruit turns brown on the inside, especially around the walls, which is known as brown wall. The un-ripened areas usually remain firmer than the red areas. This problem is prevalent in the winter and spring, and usually affects the first, second and third fruit clusters. Research and experiments indicate that climatic conditions greatly influence development of blotchy fruit. There is a high probability that blotchy ripening will develop on fruit on the first clusters under conditions of low temperature, lack of sunlight and high humidity. In autumn plantings and harsh winter conditions, the plants grow and develop slowly and a dense vegetative mass with short internodes and large leaves is produced, which covers the first clusters This type of growth greatly reduces the amount of sunlight that reaches the clusters, does not allow proper airflow, and the humidity surrounding inflorescences will not dissipate. Consequently, the fruit on these clusters are more susceptible to blotchy ripening. Other reports note that a potassium deficiency aggravates this problem, and in addition some varieties have been found to be more susceptible to blotchy ripening than others. Blotches on fruit Fruit affected by blotchy ripening Reducing blotchy ripening 1. Avoid planting during the cold autumn and winter months, when days are short and cloudy and there is little sunlight. 2. Raise greenhouse temperatures at night by heating. 3. Apply sufficient nutrients with Potassium and maintain the N:K ratio at 1:2 respectively. 4. Ventilate the greenhouse and prevent accumulation of excess humidity around the clusters and the ground. 5. Avoid dense planting, which reduces the passage of light and air between plants, especially on the lower parts of the plant. 6. In late transplanting, use white PE mulching to increase light reflection to the plants. 7. Remove leaves in order to allow penetration of sunlight to the base of the plant, when vegetation is dense. 8. Control irrigation and avoid over watering, especially in medium-heavy soil, by placing tensiometers in the soil to determine correct irrigation times and quantity. 9. Avoid planting varieties that are susceptible to blotchy ripening. Discoloration - Blotchy ripening
  • 71. 66 Diameter (mm) 50-57 57-62 62-67 67-77 77-82 more then 82 Harvesting Fruit destined for the fresh market, or fruit that is considered to be choice grade, has to be of high quality, without flaws and without bruises. Fruit damaged by bruising and perforation during harvest is not immediately detected in the packinghouse. Damage marks, excessive softness and even rotting only appear after shipping, when the fruit is marketed. In order to avoid damage to fruit it is important to be extremely careful during harvesting and grading. Quality and standards The following table indicates the recommended fruit diameters (in centimeters) for grading of single tomatoes, in accordance with local and export market demands. Table 20. Export market and local market sizes and markings for packaging 29 TOMATO HARVESTING AND POSTHARVEST When packing, the smaller fruits are packed in two or three layers, while the larger fruits are packed in one or two layers. Qualityrequirementsforgradingtomatoes 1. Characteristics of variety 2. Uniform shape and size 3. Uniform color 4. Firm, with long shelf life 5. No puffiness (hollow fruit). 6. No blotches and discoloration 7. Fresh stems and calyx 8. Clean of dust and pesticide residue 9. Short zippers on the fruit 10. No mechanical damage 11. Free of diseases and pests 12. Good taste and improved flavor Recommendations 1. Fruit should be picked at the proper stage of ripeness, corresponding to market requirements. 2. Fruit should be picked during the cooler hours of the day. Morning picking should be after condensation on plants and fruit dries up. Name Small Medium Large Extra large Giant Super-Giant 3. It is advisable not to pick the fruits when temperatures are high. Fruit that is picked at high temperatures softens quickly and is of poor quality. 4. Fruit should be picked into special containers, basins, cartons or crates that are padded with a double layer of plastic film to prevent pressure. 5. Picking containers should be dry and cleaned of all sand and plant debris. 6. Picking containers should hold only two layers of picked fruit. Fruit in the bottom layer should be placed with stems facing downwards and fruit in the top layer should be placed with stems facing upwards. 7. It is recommended to use picking trolleys that hold the containers and can maneuver between the rows, to increase efficiency of the picking process. 8. The filled containers should be placed in a shaded area to avoid overheating of the fruits. 9. Picking frequency depends on the rate of ripening and color development. Tomatoes usually need to be picked every two to five days, depending on the temperature and ripening rate. 10. Care should be taken to avoid shaking the fruit when transferring to the packinghouse because of the mechanical damage that may occur. 11. Care should be taken to prevent mechanical damage to the fruit during the grading and packing process. Picking trolley for picking between rows
  • 72. Grading and Packing The fruit is marketed in various sizes, according to their diameter. Each size is packed into separate cartons marked with the size and weight. Size grading is performed mechanically on a grading table. The various sizes are graded into separate compartments by setting the height of the grading table rulers (according to diameter) or by weight. Quality grading is manual: fruit that is not suitable for marketing is removed as it moves along a conveyor. During quality grading, damaged fruit, fruit with blotches, uneven color, irregularity, puffiness and sand or spray residues are removed. The high quality fruit is then packed into the various cartons that are weighed and marked according to their quality. 67 Stages in color development of tomato fruit This illustration shows the development of tomato fruit color, from the mature green stage (1) through to the full red stage (12). The tomato fruit reaches its maximum size at the mature green stage, when the chemical processes begin, as presented in the Changes Graph on page 7. The most important stage is the start of color development at the turning point. The mature green stage can be recognized in fruit that set and develop after pollination by the condition of the parenchyma tissue attached to the pericarp that coats the seeds. When a tomato fruit is cut widthwise with knife and the seeds are also cut, this indicates that the paranchyma tissue is stable and the fruit is not yet ripe. On the other hand, when a ripe tomato is cut widthwise, the seeds cannot be cut through, since the parenchyma tissue has changed, forming a mucous-like substance around the seeds and protecting them with its glutinous property. Simple grading table System for grading cherry tomatoes according to color and diameter Lift on a cherry tomato grading table Harvesting and handling cluster tomatoes Although cluster tomatoes are considered to be a top quality product, they are vulnerable to jostling, and therefore the option of incorporating final packaging during the picking process should be considered. This process could also be laborsaving. 1 - Green mature 12 - Full red Green and mature fruits
  • 73. 68 One of the possibilities for packing during the picking process is to use picking trolleys equipped with packaging for export. The trolleys will also have containers for fruit that has to be removed from the clusters for various reasons, such as cracked fruit (usually the first fruit on the cluster), small fruit at the end of the cluster, and other damaged fruit that is unsuitable for marketing. In addition to removing the unsuitable fruit from the clusters, it is necessary to make sure that the rest of the fruit on the cluster is free of dust and pesticide residue and therefore a small soft brush for cleaning fruit during picking should be part of the equipment. After cleaning the cluster, it is gently laid into the export carton. The cartons are finally weighed in a shaded area in the packing shed. An alternative possibility for packing is to pick the clusters into larger containers on picking trolleys that run on a conveyor that moves between the rows. Handling, such as removal of unsuitable fruit, cleaning off dust and pesticide residue, packaging and weighing, is performed in the packing shed. Cleaning systems It is recommended to wash cluster, regular and cherry tomatoes after harvest, in order to remove dust particles, chemical residue and soil, and to minimize spread of diseases. There are two main systems for cleaning fruit before final packing. 1. Cleaning dust off clusters by brushing In order to clean dust from the tomato clusters prior to packaging, it is necessary to construct a device (cleaning stand) suitable for cleaning cluster tomatoes of various sizes (large, regular, cherry) without damaging the fruit. The device should contain two brushes placed horizontally adjacent to one another and that rotate in opposite directions. The bristles should be very soft and gentle to avoid scratching the fruit and dropping them from the clusters during cleaning. The bristles should be of nylon fibers in rows of varying heights, so that the brush appears to be stepped. The brush diameter should be about 290 mm with embedded bristles. The brushes should rotate at a speed of about 80 rpm. It is recommended to build a double cleaning stand for easy and speedy operation. The motor and operating system are usually placed in the center of the stand while two sets of brushes operate on either side. The fruit-filled containers coming in from the field should be placed above the cleaning stand for easy access during cleaning. Cleaning is performed by holding the cluster between the fingers at the end of the cluster stem and “dipping” it between the brushes two or three times. The clean cluster is then placed on a moving round table close by. This table is used to collect the cleaned clusters and perform additional cleaning if necessary, and therefore the work surface should be large enough (the recommended diameter of the table is two meters). A container should be placed under each set of brushes to collect any fruit that may fall during cleaning. At the end of each day, the brushes and packaging apparatus should be cleaned and prepared for the next day. 2. Washing machines for cleaning cluster, regular and cherry tomatoes Washing machines for cleaning cluster tomatoes have a feeding belt, rinsing compartment (with spray nozzles installed above and below the conveyor belt) and a conveyor belt with fans for drying the fruit. The washing machines are differentiated mainly by the structure of the conveyer system, which transports the trays or cluster tomatoes. The machine for washing trays is suitable for 40 x 60 cm trays. The trays are fed widthwise, and therefore these machines are at least 60 cm wide. Machines that are used for individual clusters have different widths, varying from 50 cm to 1 m, according to the required output and the daily volume of fruit. One worker is needed to feed the plastic trays, while two workers are needed to feed individual clusters. A motor adjusts the speed of the conveyor belt, so that when the cluster tomatoes are removed from the washing machine, the drying action is also completed (although complete drying is not necessary). The different machines are similar only on the outside. Length is determined by the following parameters: - Feeding section: up to one meter - Closed washing compartment: about 1.2 m long - Drying section: up to 5 m long The washing system has two nozzles systems (upper and lower). It is important to use full cone nozzles with big droplets (over 300 micron) to ensure the wetting and cleaning of the clusters. There is a water-collection tray system at the bottom of the machine, which drains the dripping water and enables recycling of water used for washing. A filtration and sterilization system, (using chlorine) which is integrated into the collection tank and pump, is required for recycling this water. The recycling system can be adjusted as needed, according to the water volume used for washing and according to the number of daily work hours. When choosing a machine for washing trays, it is important to take into account the size of the general area, the harvest intervals and the quantity of planned harvest, and to ensure there are sufficient trays. At least 200 trays are needed for one ton of picked tomatoes. Do not use hot water for washing. The water should be the temperature of the water pipe. Cleaning clusters by brushing
  • 74. 69 Packaging house with washing and grading machines. Packaging system Packing is mainly performed after the washing machine. Other components, which complement the system, include: a conveyor belt, along which packing is performed at individual work stations; a gravitational or motorized roller conveyor to box the full cartons; and a weighing station for weighing and palleting the full cartons. Although the packing line is simple and short, it is important to plan the packing house to ensure optimal exploitation of the area and to achieve efficient work. It is recommended to position the packing conveyor belt directly after the washing system. Each worker should have an organized work station on which the packing carton is placed. The full carton is transferred to the gravitational or motorized roller conveyor. The conveyor for empty cartons (new) is above the roller conveyor. A weighing station at the end of the roller conveyor is important. When packing cluster tomatoes, the cartons often weigh more than necessary. Payment is not received for surplus addition, and therefore it is important to use a stable and level electronic scale, which is accurate to 10 grams. Packing systems for cluster tomatoes are suitable for all tomato varieties: cluster, cherry, midi, baby and regular tomatoes. Coarse spraying - pesticide residue Green shoulders Irregular fruit Gold speckles Malformed - Cat face
  • 75. 70 Mechanical damage and perforations Direct sunlight and sun burn Zippering ( Sutures ) Effect of sun burn internal view Blossom-end rot Crack injury Chilling injury
  • 76. 30 71 Improving the quality of tomato fruit 1. Climate: ensure appropriate temperature by heating and cooling as needed to prevent frost damage, improve color and ensure a continuous and reliable supply. 2. Controlled irrigation and fertilization prevents hollowness and blotchy ripening, improves color, increases firmness, extends shelf life and improves taste (by increasing the fruit sugar level). 3. Gentle handling during the harvesting, grading and packing processes prevents bruising, damage from stems perforating other fruit, and mechanical scratches. 4. Appropriate foliage-fruit ratio protects the fruit from frost damage in winter and sunburn caused by direct sunlight in summer. 5. Removal of excess humidity from the greenhouse improves growing conditions, reducing appearance of blotchy ripening and micro cracking and minimizing development of diseases. 6. Better fruit set improves shape uniformity and reduces fruit puffiness. 7. Better penetration of sunlight by cleaning roofs in winter reduces puffiness, increases yields and improves color. 8. Shading in summer prevents sunscald and green shoulders. It also prevents fruit turning white inside, especially around the pericarp tissue or from the stem towards the center, along the walls between the carpels. 9. Growing tomatoes in a soilless culture improves the shape and color. 10. Fine spraying with the correct nozzle and at the proper time reduces chimical residue and prevents disease and rotting during shipment. Storage of tomato fruits The optimal temperature for storing tomatoes for periods of 10 to 14 days is 10-12ºC. Varieties that are known to have a long shelf life are suitable for storing under these conditions, while varieties lacking firmness should be sold immediately after harvesting. Storage at 10º-12ºC has various purposes: To store fruit after packing until shipping to the market. This period is usually from a few hours to a few days. To refrigerate fruit during land and sea transportation to distant destinations. The storage method and the color at harvesting both affect the storage period suitable for tomatoes. For example, when the harvested tomatoes are in color they can be stored for longer, while fruit harvested at a more developed color stage can be stored for shorter periods. If the fruit is harvested at a more advanced color stage, it can be stored at a lower temperature, for example 10ºC. In general, tomato fruit can be stored for two to three weeks, depending on the ripening stage at harvest. When stored for an extended period, fruit may start to rot. Therefore the various packages have to be resorted after the storage period and before marketing, to remove any damaged or rotten fruit. Fruit is not usually refrigerated at 12ºC before grading and packaging since condensation forms on cold fruit once it is removed from refrigeration. It is therefore preferable that fruit be kept in a cool packing shed after being harvested. It is important to ensure that the fruit is graded and packaged within a short period, and that the packed product is quickly stored at 12ºC. The relative humidity recommended for storage is 90-95%. Onset of rot during storage Spread of rot Etheral is a commercial product containing 48% ethephon (2-chloroethyl) phosphoric acid that accelerates the ripening process when coming into contact with fruit, by increasing the production of plant ethylene. Israeli studies have found that fruit treated with Etheral ripen and become red quicker than untreated fruit. General review and findings of studies: Mature green processing tomatoes that were dipped in a 1,500-3,000 ppm Etheral solution ripened to full red in 12 days. Etheral sprayed on foliage of processing tomatoes works well when 25% of the yield is beyond turning stage. The suitable dosage is 30 gm active ingredient in 50 liters water per 0.1 hectare. ETHERAL TREATMENT TO ACCELERATE TOMATO RIPENING
  • 77. 72 Eighty percent of mature green tomato clusters in a greenhouse sprayed with a 0.4% Etheral solution ripened within 11 days, compared to only 67% in the untreated plots. In a greenhouse, ripening was accelerated in 88% of mature green tomatoes that were picked seven days after their shoulders were brushed with a 0.5% Etheral solution, compared to only 12% in the untreated plots. In a greenhouse, ripening was accelerated in mature green tomatoes four days after cluster stems were brushed with a 6% Etheral solution. 61% of the fruit ripened compared to 41% in the untreated plots. Etheral treatment is not common in regular tomato production in Israel although it is used in various places around the world to accelerate ripening. It is used in processing tomatoes, to accelerate ripening of fresh market tomatoes when the price is high and to accelerate ripening in greenhouses at the end of the season. Spraying Etheral on plants causes leaves to dry up and can also cause much damage to the plants. A combination of high temperature and high concentration of Etheral solution affects the severity of the damage. Introduction The growing awareness of health and environment, together with the demand for uncompromising quality of organic produce requires the use of advanced technologies when growing organic tomatoes. This combination has resulted in a growing system which meets the requirements of all organic standards, while producing a high quality and quantity yield. The produce is free of pesticide residue and the production method encourages re-cycling of waste and improves the quality of the immediate environment. Production is user-friendly and contributes to the immediate environment. Production of organic tomatoes in greenhouses requires a long-term commitment, attention to small details, performance of tasks on time, and a long-term view. Growers and field extension staff tend to test a crop by its economic performance in a single growing season. While this may be feasible with a regular crop, with organic production the crop results should be tested over a longer period. 31 OVERVIEW OF ORGANIC PRODUCTION OF TOMATOES Organic standards and inspection Modern organic agriculture should adapt itself to the local organic standard and to the standard of the target markets. In Israel, produce should be grown according to the Israeli organic standard, while adapting to the requirements of the European standard - EU 2091/92 Directive - if it is targeted for the European market, and the National Organic Program (NOP) of the United States Department of Agriculture, if it is targeted for the USA market. Some markets also require approval from the International Federation of Organic Agriculture Movements (IFOAM). Organic production should be inspected by a certified inspector for the organic standards in the target market and the regulations and standards in the source country. In the organic greenhouse, only materials and technologies meeting the approved standards and checked by the certified inspector may be used. Approval by a certified inspector constitutes reliable evidence that the product that is marketed as organic does indeed meet the organic standard for that market. Agrotechnical aspects In principle, there are no significant differences between a greenhouse for organic production and regular tomato production. It is important to maintain complete sealing by using an insect-proof net, and the greenhouse should have a double entrance to prevent penetration of insects into the greenhouse. The greenhouse should be covered with IR and UV blocking plastic to reduce the activity of whitefly and aphids. In the Arava desert in southern Israel, tomatoes can also be grown in net houses. Soils, Soil fertility and crop rotation In the organic greenhouse, crops must be planted in the local soil. All organic standards prohibit growing in soilless culture. In order to produce a successful crop, proper construction of the soil fertility should be ensured, as a principal component of nutrition for the crop and for control of weeds and soilborne diseases. The main component in soil fertility in the greenhouse is application of a generous volume of quality compost. The compost quality is important, and there should be no compromise on well-prepared compost which has completed the process of rapid decomposition and was left for a further ripening period, in which positive micro- organisms develop. These micro-organisms create resistance to the establishment of soilborne diseases and serve as a major substitute for soil sterilization. The compost should be at the same temperature as the environment when ripening, in which it does not heat up even if wetted or turned over. It should be free of weed seeds and vectors of pathogens. It is recommended to spread the compost over the greenhouse surface and to cover it with the upper soil layer. In the first years, a relatively large amount of compost is spread out, which decreases with the development of soil fertility. The amount of compost stems from the condition of soil fertility and is based on accumulated experience in the area and the condition of the plot’s fertility. The compost should be
  • 78. 73 moistened at least two weeks before planting to ensure biological activity. If possible, it is recommended to sow a soil-improving crop such as legumes or cereals in the greenhouse before planting tomatoes. The type of crop is determined according to the season and time available for growing the crop in the greenhouse. Short-term crops, such as millet also have a positive contribution to soil behavior. Asoil-improving crop or intermediate crop may serve as a partial substitute for crop rotation, which is difficult to apply in organic greenhouses due to the limited variety of crops that can be grown. One of the basic requirements of organic production is the desire to apply full crop rotation of a range of crops from different families in the organic greenhouse. It is recommended to integrate crops from the Cruciferae family, such as cabbage, cauliflower and broccoli between solanaceous crops. It is important to bury the crop debris in the greenhouse. If this cannot be performed for economic reasons, intermediate crops should be integrated for green manure. Irrigation system A drip irrigation system is recommended, with two drip laterals per bed and close dripper spacing. The drippers should have a relatively high discharge and should be resistant to clogging by organic nutrients applied through the irrigation system. The irrigation system should be well planned for uniform distribution of water over the entire greenhouse area. A collection pipe should be installed at the end of the laterals, to allow easy flushing of the drip- lines to remove any accumulated nutrient material. Varieties These should be selected according to conventional standards in the region and according to market requirements, especially for export markets. In most cases, the conventional varieties are also compatible with regular agriculture. Multi-resistant varieties are recommended, especially those that are resistant to soilborne pests, as well as show resistance to viral or leaf diseases. Grafted plants may also be considered in nematode-infested plots if there is no suitable variety that is nematode-resistant, or resistant to other soil-borne diseases. Preparation of greenhouse for planting The greenhouse should be sealed and cleaned of weeds and crop after-growth at least two weeks before planting, to prevent establishment of pests in the greenhouse. If the soil fertility is low, feather meal can be added to enrich the soil with nitrogen. If feather meal is added before autumn planting, care should be taken to avoid excess nitrogen in the soil, which may damage the young plants. During this period, irrigation should be applied and the soil should be kept moist, to ensure proper microbial activity in the compost. It is recommended to hang up yellow sticky traps and to wrap greenhouse posts and coverings with yellow sticky film to trap whitefly, and with blue sticky film to trap thrips. The greenhouse should be brought to biological balance by crop rotation, intermediate crops, green manure and use of good compost. If nematodes or pathogenic soil fungi have developed in the greenhouse, it is recommended to integrate soil solarization. In particularly severe cases, it is recommended to consult a field extension specialist and to consider steam sterilization or use of grafted plants. Planting Before planting, weeds that germinated in the greenhouse after application of compost should be removed by light plowing or raking. The seedlings should be protected from Bemisia tabaci (whitefly) from the time that they are removed from the nursery until they are brought into the greenhouse. It is important to ensure that the greenhouse is sealed during planting. Before planting, the plant’s root plug should be saturated with water. If the plug is dry, it is important to wet it before planting, by dipping it in water. The seedling should be planted in moist soil with planting holes dug by hand or with a planting pick. The seedling should be placed in the hole and the soil around it should be gently pressed down. Post-planting activities in the greenhouse After planting, it is important to irrigate lightly and to continue with light irrigation until white shoots develop from the plug. When the shoots develop, irrigation intervals should be spread out to the maximum, without causing damage to the seedlings. These irrigation intervals encourage establishment of a large root zone and prevent lack of aeration in the soil. Lack of aeration encourages wilting diseases and accumulation of nitrites, due to termination of the nitrification process as a result of oxygen deficiency (nitrite is toxic for plants). Fertilization and irrigation At the beginning of growing, irrigation is applied without nutrients. The soil in the organic greenhouse is rich in nutrients from the compost and feather meal. Crop development does not need to be encouraged too much before fruit set, to avoid development of a plant which is too large and vegetative. In regular agriculture, where compost is not applied, it is customary to apply moderate amounts of fertilizer. When the plants develop, it is recommended to consider addition of approved organic fertilizer near the drippers, or application of liquid organic fertilizer through the irrigation system, according to the plant’s appearance and the fertility of the soil. Fertilizer should be applied carefully and excess fertilization should be avoided, as it may encourage damage and lead to unbalance in the plant. The types and quantities of fertilizers are determined by their accessibility, the condition of the plants and the fertility of the greenhouse. Therefore they are adapted to the time and place and it is not possible to provide an accurate growing recipe. In Israel, it is conventional to use solid guano or guano extract (bird manure from Peru or Namibia) and fermented cow manure, which is approved by certified inspectors. Soil-improving elements can also be added, such as amino acids and microelements approved for use in organic agriculture.
  • 79. 74 Plant protection Leaf diseases and pests are controlled according to organic standards in the season and area, while striving to create optimum conditions for growing and poor conditions for the pest or fungus. Creation of a biological balance is preferred, and if intervention is required, mass trapping or disorientation is recommended. When there is no other solution, pesticides approved for use in organic agriculture are applied. When pesticides are applied, it is recommended to use substances and methods that do not harm natural enemies. Principal pests and possible solutions in organic agriculture Tomato yellow leaf curl virus (TYLC) Control is by sealing greenhouses with a suitable screen, hanging yellow sticky traps, covering poles and greenhouse coverings with yellow sticky film and application of approved substances, such as LQ215 detergent combined with Azadirachtin, which is the active ingredient of neem seed extract. When using these substances, it is important to ensure that they are included in the list of materials approved for use in organic agriculture, which is updated periodically and published on the website of the Ministry of Agriculture PPIS department Israel or other local certification body. It is recommended to remove contaminated plants from the greenhouse. Russet mite This pest can be controlled by powdering, spraying or vaporization with approved sulfur materials, preferably liquid sulfur, which are less harmful to natural enemies and to the plastic covering the greenhouse. Sulfuric vaporization can also be considered, with a lower application per hectare and operation of 4 hours at night. Care should be taken when applying sulfur when bumblebees are used in the greenhouse for pollination. Sulfuric treatment is also efficient for control of powdery mildew. Late blight Integrated control is required for late blight, including sanitation, removal of lower leaves and contaminated leaves, spraying with approved substances and maintenance of low humidity. In humid regions, it is recommended to consider covering soil with plastic to reduce the humidity in the greenhouse. The recommended method today is combination of neem oil with approved copper substances. Use of copper may be prohibited soon, and efforts are being made to find an efficient substitute. It is recommended to consult with a field extension specialist for information on control of other pests. Postharvest When harvesting, sorting and packing, it is recommended to maintain proper conditions for preserving the fruit quality and to apply conventional treatments, such as hot brushing, which is also suitable for organic fruit. However, other treatments are prohibited, and therefore special care should be taken to ensure sanitation in all handling processes. Organic production is a way of life, requiring long-term commitment, and is not just another production method. Organic production is still developing, and therefore it is recommended to work together with field extension specialists researchers and experienced organic growers, who are familiar with the subject of organic agriculture, in order to achieve crop management which is compatible with the time, place and grower. Tomato plants are susceptible to many diseases and pests, some of which affect numerous other crops and some of which are specific only to tomatoes. Tables describing the various types of damage according to their specific groups appear below. Pest control is a significant part of tomato production costs. In recent years, efforts have been made to reduce the use of pesticides for various reasons: 1. Saving in production costs 2. Prevention of toxic residues on fresh produce and in foodstuff 3. Prevention of air pollution and environmental damage Pest control methods are divided into groups: 1. Conventional pest control: the application of chemical pesticides as routine preventative treatment (proactive approach), and then following the appearance of a particular disease or pest. 2. Agro-technical methods which are complementary to or are an alternative to chemical pest control. These methods include physical protection of crops using special greenhouse coverings such as special plastics, nets (insect proof), double doors, soil mulching and climatic manipulation to minimize conditions for the development and spread of insects and diseases, soil mulching reduce conditions for development of leaf diseases. Solar sterilization of the soil and greenhouse space is now a common and widely used method. In addition there is steam sterilization which is limited to substrates and light soils. 3. Biological pest control: Using predators to control insects and colored sticky traps that attract insects, in order to monitor and reduce the insect population. 4. Genetics: Growing varieties that are resistant or tolerant to specific diseases and the use of rootstocks to prevent soil-borne diseases. 32 DISEASE AND PEST CONTROL
  • 80. 75 Undoubtedly, these auxiliary means are beneficial and are intended to reduce the use of chemical pesticides. Nevertheless, the application of chemical pesticides is still the most commonly used and important method for protecting plants from pests and diseases. Details of the recommended chemical preparations can be found in the booklet “Recommendations for Pest Control in Vegetables”, published by the Agricultural Extension Department of the Ministry of Agriculture and Rural Development in Israel (published in Hebrew). Sanitation of greenhouses and surroundings Greenhouse crops should not be planted unless the greenhouse has undergone suitable preparation to include sterilization of the soil or soilless culture media. Clean the greenhouse of refuse, and ensure that the water drainage system in the greenhouse is operating properly. All remaining stalks, leaves and fruit, as well as all the weeds inside and outside the greenhouse, which could host diseases, hide pests, and prevent proper airflow, should be removed from the greenhouse. It is extremely important to ensure good ventilation and hence a good environment for healthy plants. The following cleanup process is recommended for greenhouses at the end of a crop and before planting a new crop: At the end of the crop, the plants should be pulled out of the soil. Every effort should be made to remove all parts of the plants, including as much of the root system as possible. In soilless culture, where large containers such as long polystyrene tubs are used, it is easier to remove the plants with their root system after they dry out slightly. In other containers such as buckets or bags, the plant stems should be cut as close as possible to the substrate surface. The plants should be removed whole, and unnecessary shaking should be avoided to preventspreading spores or broken off parts of diseased plants. The plants that have been removed should be collected and destroyed by burning in a remote area that is not intended for agriculture and is not close to residences. Before replanting and after preparing the greenhouse, a basin or tray containing a foam mat soaked in a 3% chlorine solution, should be placed at the entrance to the greenhouse. This device is for cleaning shoes every time anyone enters the greenhouse, to prevent the recently sterilized soil becoming contaminated with pathogens (which cause soil diseases). Every time the foam dries out, it should be re-soaked with the solution. Yellow sticky trap for insect monitoring P. persimilis - spider mite predator Diglyphus – leaf miner predator
  • 81. 76 Clean healthy environment Materials for plant protection The use of plant protection materials in tomato production for the export and local markets are su bject to the directives of the target markets. Pesticide residue on fruit is examined in Israel and abroad, and the fruit is rejected if residues of prohibited products or levels higher than those permitted are found. Instructions regarding these subjects are published every year in many countries and in Israel by the Plant Protection Department of the Ministry ofAgriculture and Rural Development (in Hebrew). Lists of products permitted for use on tomato crops are found in these publications. Information is also included regarding the number of days a specific chemical can be used before harvesting. This is based on the assumption that the material will begin to break down over this period and that the residue level will decrease to non-harmful levels. Pesticides are applied to greenhouse tomato crops as preventative measures and as reactive treatments to stop insects from spreading and to prevent establishment in the greenhouse of any type of pest that might cause direct or indirect damage to the plants. Most commonly used pesticides are marketed in various forms, such as soluble and suspendible powders, soluble granules, concentrated suspensions, emulsions and liquid solutions. Pesticides are usually applied to plants by spraying. The plants should be sprayed in such a way that the solution reaches all parts of the plants, entirely covering the foliage, to ensure total control of all pests and pathogens on the various parts of the plants. Pesticides are usually applied in small quantities per plot and it is difficult to spread them evenly in their marketed form. To ensure even distribution on foliage and to prevent damage to plants, the various pesticides are diluted and mixed with water, separately or in combinations. This depends on the type of damage the chemicals are meant to prevent, the sprayer volume and size of plot to be sprayed. Directions for use appear on the packaging for each product, indicating quantities of solution to be used per plot size, and these recommendations should be followed. Various methods and types of sprayers are used to apply pesticides. The different types of sprayers have diverse actions, droplet size and volume requirements in order to obtain the best results. Pesticide application methods for greenhouses 1. Motorized backpack sprayer: operated by a gasoline motor. The motor activates a blower that drives high velocity air (more than 80 m/sec) through the spray hose and nozzles. The solution is delivered through the nozzles to the plants in tiny airborne droplets. The size of the droplets ranges from 50 to 200 micron. Motorized backpack sprayers are considered the most important greenhouse pesticide application tool. 33CHEMICAL SPRAY APPLICATION TECHNOLOGIES Motorized backpack sprayer Poor sanitation – source of diseases and pests Poor sanitation
  • 82. 77 The volume of solution in this spraying method is 500 - 800 liters per ha. of mature plants. The operators of this type of sprayer carry the sprayer on their back and hold the spray gun in their right hand while the left hand gradually activates the fuel lever to its maximum position when starting to spray. The worker first opens the valve for the fluids and then directs the spray gun towards the plants in such a way that the airflow reaches the plants 3 meters ahead. The spray height should be directed towards the middle and upper plant parts and the hand and nozzle kept level and steady. An “up and down” hand movement should never be used. 2. Fixed greenhouse sprayer: usually positioned outside the greenhouse and attached to it by a system of pipes fixed along the length of the greenhouse. The pipe system includes valves with quick couplings for connecting to a flexible hose that is attached to the spraying mechanism, either a spray gun or a mobile vertical spray-pole. The sprayer tank is fitted to a pump that operates according to various factors such as pressure, flow and rpm. Minimum 30 atm. pump pressure is required and flow capacity required in greenhouses is 60 l/min. The fixed pipe system usually consists of half inch galvanized tubes and has valves with quick couplings for connecting the flexible hose, fitted along the length, and a valve for cleaning and draining the pipe system fitted at the end. A portion of flexible pressure hose should be connected between the fixed pipe system and the tank, to prevent the tank from being damaged when the sprayer vibrates. The mobile hose is usually a 3/8 inch flexible hose able to withstand 40 atm. The length of the flexible hose should equal the length of the row, plus half the distance between the row and the valve fitted to the fixed pipes. The spray gun for greenhouses is operated by a valve that is also the handle. The spray gun handle can be fitted to a vertical pole made of sections of thin, lightweight tubing that enable nozzles to be attached at 25-30 cm spacing. The bottom of the spray-pole should be 20 - 30 cm from the ground with the option of fitting two nozzles at the bottom to cover the lower parts of the plants. The height of the spray-pole should be according to the Sprayer tank The conventional solution volume for this spray method is 500-1,200 l/ha of mature plants. During spraying, the operator activates the spray gun and directs it up and down to ensure complete coverage of the foliage. This action is usually performed by holding the spray gun in the right hand and spraying the left side while walking up the row and repeating the operation while coming back down the row. The operators pace should be 1.5-3 kmhour. On the other hand, in order to avoid getting wet from the spray pole and the sprayed plants when spraying with a vertical spray-pole, it is recommended that the operator walks up to the end of the row with the spray-pole and then operates it by opening the activation valve while slowly walking backwards back down the row. 3. Air sprayers: Israeli manufacturers have recently developed several types of sprayers for spraying greenhouses with air. The principle of the method is to force the solution out of the sprayer with the air current. This action turns the leaves, so that both top and bottom sides are covered almost equally. The plant height, with the option of extending and adding nozzles when needed as the plants grow. A single or double adjustable spray-tip nozzle is fitted at each spray junction. A quick coupling should be connected to the spray-pole to attach it to the solution supply hose. The spray-pole is connected vertically to the centre of a two-wheel trolley with a handlebar. The width of the wheels should enable easy passage along the paths between the rows. The trolley should be fitted with a coupling for a flexible hose, an activation valve for operating the spray-pole and a pressure gauge similar to the one attached to the spray gun, so that the true spray pressure can be seen. A flexible tube is also necessary for the flow of solution from the gauge to the spray pole. Vertical pool of nozzles
  • 83. 78 spray nozzles suitable for this method are elbows or spray system nozzles, which are hollow cone nozzles that generate the required pressure of between 5-10 bars. The air sprayers are narrow vertical sleeve boom sprayers and track-driven greenhouse sprayers. A width of 70 cm between rows is required for this equipment. Narrower equipment (60 - 64 cm has also been developed, such as, sleeve sprayers and boom sprayers) . This spraying method is more efficient than the other methods. Air sprayer 4. Low volume sprayers: Cold foggers in greenhouses. In the search for more efficient greenhouse chemical spray application methods that are both labor saving and minimize the use of chemicals, new technologies such as foggers that dispense cold fog have been introduced. Fogging disperses chemical spray throughout the greenhouse without the operator being present. This technology is based on two consecutive operations: creating aerosol (tiny droplets, less than 20 microns) and distributing it throughout the greenhouse atmosphere with the regular air currents. The aerosol created by the cold fogger does not require the pesticides to be heated to high temperatures and therefore a very wide range of products can be used with this form of application. Asmall volume of solution is required for fogger application, 10 liters per ha. is sufficient. Recent experiments show that distribution is more even when circulation fans operate inside the greenhouse during the fogging process. Pesticide application by cold fog requires the use of equipment approved by the Institute for Agricultural Engineering. Air currents easily carry the tiny droplets (5 - 25 microns) through any tear or hole and are liable to pollute the outside environment, causing possible harm to people, animals, and even to other plants. Therefore, to prevent pesticide clouds from escaping to the outside atmosphere, it is essential to ensure that the greenhouse is completely sealed while operating a fogger. It is recommended to fog in the late afternoon or evening. The greenhouse can be reopened three hours after the fogging process has been completed. There are many flaws and disorders in tomato fruit and plants that are not caused by insects or pathogens. Some of these disorders appear on the plant foliage and/or on the fruit. These disorders usually cause damage to fruit quality as well as to the yield. These non-pathogenic disorders are affected mainly by climatic conditions and by agro-technical methods which encourage their appearance. The table below presents a general review of the non-pathogenic disorders in tomato production. 34 NON - PARASITIC DISORDERS Cold fogger Air sprayer
  • 84. 79 Table 22. Non-parasitic disorders Blossom- end rot Light tan, water-soaked lesion spot at the base of the fruit that grows and usually turns black and leathery. All year round Regular irrigation; balanced fertilization; correct calcium concentration; use varieties tolerant to BER. Gold speckles Golden spots around the calyx and on the fruit shoulders that usually spoil the external appearance and cause the fruit to soften quickly, thus reducing shelf life. This is an accumulation of calcium oxalate crystals in cells under the epidermis. Winter and spring Use varieties tolerant to this condition. Proper levels of nitrogen and general plant nutrition. Fruit cracking Micro, Radial and Concentric cracks. Cracked fruits are not suitable for marketing. Spring, summer and autumn Tolerant varieties, proper fertigation program to prevent succulent plants, limit fruit exposure by encouraging leaf cover of fruit, reduce humidity Chilling injury Glassy or watery marks on the fruit. Plant foliage becomes purple or black and dries up. Winter when temperatures drop below 6oC Prevent chiling by heating the greenhouse. In addition ensure good air circulation. Use IR thermal plastic covering. Nutritional deficiencies Generaly yellowing leaves and a typical element deficient. All year round Adding the deficient elements, usually iron, magnesium and manganese; avoiding deficiency by proper nutrition. Phytotoxicity of chemicals Leaves or other parts of the plant appear burned by fertilizers or chemical sprays. All year round Use correct dosages of chemical and fertilizer sprays; only use recommended chemical combinations. Diease Sunscald Damage The part of the fruit that is exposed to direct sunlight becomes yellow or white. Varieties with green shoulders are more susceptible. Season Summer and autumn Control Prevent fruit that has been shaded from sudden exposure to the sun. The greenhouses should be shaded or whitewashed during the risky seasons. Grow thick foliage to protect clusters from being exposed to direct radiation. Silvering Sudden change in the leaf color, starting with parts of the leaf turning silver and spreading to the whole leaf. The fertility of these plants is reduced and fruit does not form. Incidents of silvering and symptoms appear under poor climate conditions, as a combination of low temperatures during the days (below 180 C) and a lack of radiation. Poor climate conditions Avoid sensitive varieties; leave side shoots as thay may not show the symptoms. Replace by growing side shoot of the neighbor plant. Puffiness (hollow fruit) Fruit shape is usually distorted, appearing flat sided or angular; when cut spaces can be seen between the locules contents and the walls of the fruit. All year round Tolerant varieties; balanced fertilization; aviod excess irrigation; proper use of growth hormones. Winter Proper spacing between plants in the greenhouse; cleaning roofs to improve light intensity; heating during cold winter. Blotchy ripening Gray - brown spots or stripes that are visible on the skin as well as inside the fruit. The phenomenon is known as Brownwall. Winter and Tolerant varieties; proper fertilization, good light and removal of excess humidity; heating during cold winter. Spring Zippering Thin brown necrotic scars from the calyx towards the base of the fruit, in different lengths caused by anthers being attached to overy wall. Summer and autumn Tolerant varieties; prevent stress condition; extreme temperatures and excess humidity. Oedema Small bumps that split on the underside of the leaf and are caused by a combination of high humidity and low temperature. Autumn and winter Good ventilation and reduction of humidity.
  • 85. 80 Oedem on leaves Table 23. Parasitic plants and other weeds that attack tomato plants Disease Orobanche spp Damage Parasitic plants cause direct damage to tomato plants. There are different types of Orobanche with typical flowers, white and purple. Season All year round Control Soil sterilization, avoid spreading seeds on cultivation equipment; avoid grazing and entry of animals into the growing area. Cuscuta campestris Parasitic plant, yellowish, clings to all parts of the tomato plant and causes it to distort. Late spring, summer and autumn Chemical herbicides; avoid spreading seeds as above and through water system. Clean external greenhouse surroundings. Other Weeds All kinds. Could germinate in greenhouses used for growing tomatoes and cause direct damage to tomato plants. Weeds are also hosts for insects and diseases. All year round Cleanliness - weeding the greenhouse surroundings; soil sterilization; use of soil mulching and herbicides. Application of wrong material (chemical) Silvering Weeds are plants that grow in unwanted places at unsuitable times. Weeds cause damage to cultured plants, including tomatoes, in various ways: 1. They compete for and deplete nutrients and water in soil. 2. When weeds grow next to cultured plants, they undergo rapid growth and elongation of the stem because of competition for light. This causes the cultured plants to weaken and reduces their yield. 3. Weeds are host to pests and diseases that are easily transferred to cultured plants and contaminate them in various ways. 4. Certain weeds cling directly to the cultured plants and thereby deplete the moisture and nutrients in the plants causing them to weaken and eventually die. Various ways to fight weeds: 1. Mechanical eradication by tilling, plowing, and rotovating. 2. Chemical eradication by soil sterilization such as Methyl Bromide or selective use of herbicides. 3. The use of opaque plastic film that prevents the sprouting and development of seeds that lie under the plastic. 35 WEEDS AND PARASITIC PLANTS
  • 86. Soil-borne diseases are usually caused by fungi and bacteria that can be sustained in the soil for years. The damage caused by these pathogens is severe and causes enormous financial losses. Contamination by some of these pathogens can result in young plants dying off immediately after planting. Examples of this are the damping off diseases. In older plants, there can be wilting before or even during harvest, due to root rot or damage to the xylem vessels. In both cases, where both young seedlings and adult plants are damaged, the yield loss is great in quantity as well as quality. Efforts are made to minimize these types of affliction as much as possible, based on the assumption that a constant number of plants throughout the season will guarantee the potential yield per plant and the expected yield per planting. Soil sterilization is the conventional method to control these soil diseases. Crop rotation helps reduce the pathogen population while traditional genetic breeding develops varieties that are tolerant or resistant to these diseases. Based on the assumption that in the future fewer pesticides will be used and the fact that crop rotation is not possible in greenhouse production, it appears that development of resistant varieties is the most efficient method for successfully fighting soil-borne pathogens. Successful genetically engineered disease-resistant tomato varieties include resistance to Fusarium oxysporum f.sp. lycopersici, Verticillium dahliae, and Fusarium oxysporum f.sp. radicis, and the successful development of varieties that are partially resistant to root-knot nematode that have become very common. Among the most efficient methods for controlling soil-borne diseases are soil sterilization (chemical and solar) and traditional plant breeding for soil-borne disease resistance. In addition, another method that is gaining popularity involves grafting desired variations onto a suitable rootstock that has the appropriate range of disease resistance. 36 SOIL-BORNE DISEASES 81 Orobanche spp. in greenhouse Table 24. Soil-borne fungal diseases Disease Damping off diseases Cause: Various fungi, such as: rhizoctonia solani, Pythium spp. Alternaria spp. Description Season Control Damage to young seedlings while in nursery or field. Seedlings turn black, shrivel at root-stem junction and wilt. All year round Soil and seed sterilization; avoid humidity and excess moisture in soil and substrates. Fusarium wilt Races 1 and 2 Fusarium oxysporum f.sp. lycopersici Plants rot and dry up, xylem vessels turn brown. The plants wilt completely. Mainly during the hot seasons. In high soil infection the diseases will be all year round Resistant varieties; soil sterilization; rootstock- grafting. Verticillium wilt Verticillium dahliae Adult plants rot and dry out, xylem vessels turn brown. The plants wilt in the day and recover at night but usually die. All year round Resistant varieties; soil sterilization; rootstock grafting. germination of weeds Cuscuta campestris climbing on foliage
  • 87. 82 Disease Southern blight Sclerotium rolfsii Description Season Control Roots and stems at soil level rot; plants wilt and dehydrate; white mycelium and light brown spots appear on the roots and stems at soil level as well as on fruit lying on the ground. Summer, combination of high temperatures and high humidity conditions. Soil sterilization; solar sterilization; prevention of excess moisture in soil. White mold Sclerotinia sclerotiorum Root, stem and fruit rot. Dried hollow stem with black bodies known as sclerotia. Winter and spring. High humidity conditions and moderate temperature encouraging the disesase. Soil sterilization; ventilation; chemical fungicides soil mulching. Corky root Pyrenochaeta lycopersici Plant degenerates, roots have brown lesions arranged in bands with 2.0-5.0 cm lengthwise cracks. Winter and spring. Spreads in heavy soils. Crop rotation; soil sterilization; rootstock grafting. Crown and root rot Fusarium oxysporum f.sp. radicis-lycopersici Adult plants can wilt, root systems dry with brown rot in cortex and xylem, stem cankers at soil level; 20-30 cm of the stem above soil level becomes grayish-pink with brown center. Winter and spring. Spreads under saline conditions. Resistant varieties; sterilization of seeds, soil, and greenhouse atmosphere; rootstock grafting. Pythium damping off Damping off – fullness and lack of uniformity Fusarium – Crown rot Fusarium wilt of susceptible tomato variety Fusarium – Crown rot Infection with pythium
  • 88. 83 While most of the fungi that attack tomato plants are pathogenic and microscopic, a few are macroscopic. Parasitic fungi develop mycelia, have insufficient chlorophyll and therefore, invade host plants to obtain carbohydrates. More than one pathogen is often present in tomato plants at any given time. This indicates the existence of conditions suitable for their development and their ability to cause foliage, stem and fruit diseases. These fungi and the diseases that they cause can be controlled by eliminating and avoiding the conditions that promote their development, such as humidity and high or low temperatures, or a combination of both. Pathogenic fungi reproduce in various ways that enable them to spread far and thus reach hosts in different places and cause diseases when the conditions are right. Due to its importance, data regarding late blight caused by the fungus Phytophthora infestans is presented in Table 25. This disease is widespread in most tomato growing areas and affects tomatoes and potatoes. An epidemic outbreak of the disease could cause very severe financial losses. Late blight attacks leaves and stems, forming large 3-4 mm brown spots with a grayish-white halo (mycelia and spores). Dark brown spots form on the stems and petioles (leafstalks) and as the disease develops in the field, the vegetation seems to wither. Dry or firm brown rot develops on the infected tomato fruit. The fungus produces lemon-shaped sporangia which, in the presence of adequate water at 15ºC for 4 - 6 hours, release zoospores. Mycelia develop in plant tissue in temperatures of 18-20ºC. This disease develops especially in humid conditions, in spring and autumn, when the nights are cool and the days are warm. Sprinkler irrigation Tomato plant infected with verticillium dahliae Pyrenochaeta lycopersici - Corky root Roots infested with nematodes Sclerotium rolfsii (southern blight) 37 TOMATO LEAF DISEASES
  • 89. 84 encourages the conditions for development of this disease when temperature conditions are right. Hot dry weather delays and even suppresses development of the disease. Today the most widespread control methods are agro- technical, and involve preventing conditions for the development of the disease, such as avoiding wetting the plants, removing excess humidity, and greenhouse ventilation. Table 25. Fungal leaf diseases Alongside this method, there are also chemical control methods through preventative or systemic chemicals. However, the repeated use of these substances results in the development of resistant strains of the fungus. Consequently, a wise Integrated Pest Management (IPM) routine is one that combines agro-technical and chemical methods. Disease Late blight or tomato blight Phytophthora infestans Description Season Control Dark spots on leaves, stems and fruit. In severe cases, the entire plant dries up. Spring and winter and sometimes autumn Prevent moisture on the plants; good ventilation and chemical control; soil mulching. Early blight Alternaria solani Circular spots, usually concentric, on the leaves, stems and fruit, especially adult plants. All year round Prevent moisture on the plants; good ventilation and chemical control; soil mulching. Gray leaf spot Stemphylium solani Small round or elongated, brown-black spots on leaves and stems that often dry out and crack. All year round Resistant varieties; chemical control; prevent unnecessary humidity; soil mulching. Powdery mildew Leveillula taurica Yellowish spots on leaves, white spores usually on the underside of leaves and sometimes on the upper side. All year round - on adult plants the disease develops quickly in warm and dry environments Chemical control immediately with appearance of symptoms; tolerant varieties. Gray mold Botrytis cinerea Gray rot on leaves, stem and fruit accompanied by gray spores. Ghost spots on fruit. Autumn, winter and spring, high humidity- encouraging infection with Botrytis Prevent moisture on the plants; good ventilation, chemical control and sanitation; soil mulching White mold Sclerotinia sclerotiorum Rot at the base of stems, stems, fruits and leaves. Hollow stem with black sclerotia in the pith. Winter and spring high humidity Soil sterilization; ventilation; chemical control; soil mulching. Leaf mold Fulvia Fulva Cladosporium Fulvum Yellow spots on leaves, greenish-gray spores on the underside of leaves. Summer, autumn and winter. High humidity, the disease develops quickly at 20º-27ºC. Prevention of humidity; resistant varieties; chemical control and soil mulching. Powdery mildew Oidium lycopersici Irregular white spots on the upper side of the leaves, strong infected leaves usually become yellowish and non-effective. All year round Chemical control immediately with appearance of symptoms.
  • 90. 85 Botrytis – Ghost spots Botrytis – Stem rot Fruit rot Early blight (Alternaria solani) on seedlings Early blight on fruit Botrytis Early blight on leaves
  • 91. Powdery mildew - Oidium lycopeici 86 Powdery mildew - Leveillula taurica White mold dried stem with sclerotia White mold on stems Leaf mold - Fulvia fulva
  • 92. 87 Infection on foliage and fruit Fruit infection Infection of tomato plants and fruit with Phytophthora infestans (late blight) Foliage infection
  • 93. 88 In the group of plant diseases that are caused by bacteria, the various types of diseases are distinguished according to the affected area and the appearance of damaged tissue. Accordingly, the best-known types are: 1. Parenchymatous diseases that cause rot or necrosis of the parenchyma tissue; the final result is wilting of the plants. 2. Diseases that develop local necrosis, in which case the damage is local. The developing spots have round or ribbed shapes. 3. Diseases causing various parts of the plants to die off. Bands encircling parts of the plant that cause the branches or young shoots to die off. 4. Diseases of the xylem vessels. Diseases that develop in the xylem vessels of plants and damage the xylem, resulting in the plant wilting and dying. Note: Soil treatment with Formalin is effective in controlling bacterial plant pathogens occurring in Israel, such as Clavibacter michiganensis, streptomycess spp. and others. 38 BACTERIAL DISEASES Bacterial speck on foliage Table 26. Bacterial diseases in tomatoes Disease Bacterial speck Pseudomonas syringae tomato Description Control Bacterial spot Xanthomonas campestris vesicatoria Tomato pith necrosis Pseudomonas corrugata Bacterial soft rot Erwinia cartovora Southern bacterial wilt Pseudomonas solanacearum Bacterial canker Clavibacter; corynebacterium michiganensis Brown angular spots with a clearly defined yellow halo on leaves. Brown dark spots of 3-4 mm on stems, fruits with a dark green halo around them. Spreads in wet weather, wounds plants by drops of water from covers and gutters which encourages infection. Lower leaves drop off followed by wilting of the entire plant, no yellowing occurs with this disease. When the stem is cut a slimy gray material oozes out. The disease spreads under high humidity - tropical and subtropical conditions. Soft rot on stems, yellowing of foliage. Part of the stem becomes brown causing wilting of the plants. In dry conditions diseased plants overcome the infection and grow again. Hollowing of the pith, stems rupture. Plants wither and wilt. Small cankerous and white spots on fruits, stems, leaves and brown in the center resembling a bird’s eye. Leaflets turn yellow and plants wilt completely. Brown area on the stems and the pith look glossy and darker near the vessels. Appearance of adventitious roots causing splits on stem. High humidity and high levels of nitrogen and vegetative growth encourage the bacteria. Irregular brown spots on leaves and along the stem sometimes the center of the spots dry and fall out. Fruit infection began as small black spots which later become brown and scabby spots surrounded with an oily halo. Seed treatments, crop rotation, avoidance of moisture on the plants and use of copper materials in case of infection; use tolerant varieties to bacteria. Use disease-free seeds; avoid high humidity in the greenhouses; good sanitation and control by copper materials. Soil drying and sterilization, removal of diseased plants from greenhouses. Good sanitary conditions by pruning and correct handling of the plants. Soil and seed sterilization, use crop rotation and good sanitation by plant pruning and management. Good sanitation, avoid high humidity; Good sanitation. Use crop rotation; soil drying and sterilization. Since the bacteria survive in soil, needs crop rotation; soil sterilization and use of rootstocks for grafting. Bacterial speckBacterial spot
  • 94. 89 Bacterial canker Viral diseases differ from other parasitic diseases. Other parasitic disease pathogens can be identified with an optic microscope, while viral disease pathogens can only be distinguished with an electronic microscope. Viral pathogens have various shapes - ball, string or stick - and they are measured in nanometers (millionth of a millimeter). The chemical composition of plant viruses is relatively simple and those that have been examined are composed of protein and nucleic acids. Viral diseases can be identified according to their important vector and symptoms. 39 VIRAL DISEASES Viruses can be divided into two main groups: 1. Non-persistently transmitted viruses: The virus is acquired by a vector in a short acquisition period from an infected plant and is immediately transmitted to a healthy plant. However, the vector looses its infecting ability after short period of time. 2. Persistent transmitted viruses: A vector acquires the virus in a long acquisition period for a relatively long period. The virus can only infect a healthy plant after an incubation period in the insect’s body. A relatively long period on a healthy plant is required for the virus to be transmitted. In this case, the virus is usually persistent in the vector that continues to transmit the virus during its lifecycle. Due to the significance of the tomato yellow leaf curl virus (TYLCV) in tomato production, a review describing the main characteristics of this virus follows: Tomato yellow leaf curl virus (TYLCV) TYLCV geminivirus causes severe damage to tomato crops in Israel and other countries. The disease causes normal growth to stop, new leaves are small and curled in groups at the top of the plant and they often become yellow. The damage is most substantial when young plants become infected and there is generally no fruit set. This virus is universally widespread and can today be found in the Mediterranean region, Africa, Asia, Eastern Europe including the CIS, Latin-American countries, the Caribbean Islands, Australia and it has recently also been found in Florida in the USA. Its wide distribution is mainly caused by transport of infected plant material or infected whitefly vectors. The virus is transmitted exclusively by the tobacco whitefly (Bemisia tabaci). It is not transmitted mechanically; however it can be transmitted through grafting. The virus is not transmitted through seeds or by physical contact between plants or by cross-pollination. Stranglewort (Cynanchum acutum), little mallow (Malva parviflora), jimsonweed (Datura stramonium) sow-thistle (Sonchus oleraceus) and certain tobacco varieties are among the alternate virus hosts identified so far. Pseudomonas corrugata
  • 95. 89 Bacterial canker Viral diseases differ from other parasitic diseases. Other parasitic disease pathogens can be identified with an optic microscope, while viral disease pathogens can only be distinguished with an electronic microscope. Viral pathogens have various shapes - ball, string or stick - and they are measured in nanometers (millionth of a millimeter). The chemical composition of plant viruses is relatively simple and those that have been examined are composed of protein and nucleic acids. Viral diseases can be identified according to their important vector and symptoms. 39 VIRAL DISEASES Viruses can be divided into two main groups: 1. Non-persistently transmitted viruses: The virus is acquired by a vector in a short acquisition period from an infected plant and is immediately transmitted to a healthy plant. However, the vector looses its infecting ability after short period of time. 2. Persistent transmitted viruses: A vector acquires the virus in a long acquisition period for a relatively long period. The virus can only infect a healthy plant after an incubation period in the insect’s body. A relatively long period on a healthy plant is required for the virus to be transmitted. In this case, the virus is usually persistent in the vector that continues to transmit the virus during its lifecycle. Due to the significance of the tomato yellow leaf curl virus (TYLCV) in tomato production, a review describing the main characteristics of this virus follows: Tomato yellow leaf curl virus (TYLCV) TYLCV geminivirus causes severe damage to tomato crops in Israel and other countries. The disease causes normal growth to stop, new leaves are small and curled in groups at the top of the plant and they often become yellow. The damage is most substantial when young plants become infected and there is generally no fruit set. This virus is universally widespread and can today be found in the Mediterranean region, Africa, Asia, Eastern Europe including the CIS, Latin-American countries, the Caribbean Islands, Australia and it has recently also been found in Florida in the USA. Its wide distribution is mainly caused by transport of infected plant material or infected whitefly vectors. The virus is transmitted exclusively by the tobacco whitefly (Bemisia tabaci). It is not transmitted mechanically; however it can be transmitted through grafting. The virus is not transmitted through seeds or by physical contact between plants or by cross-pollination. Stranglewort (Cynanchum acutum), little mallow (Malva parviflora), jimsonweed (Datura stramonium) sow-thistle (Sonchus oleraceus) and certain tobacco varieties are among the alternate virus hosts identified so far. Pseudomonas corrugata
  • 96. 90 Most commercial tomato varieties are susceptible to the virus. Bean plants are also susceptible to this virus. In cut flower production in Israel, TYLCV has also seriously affected Lisianthus spp. The pathogen has been identified as having Gemini-shaped molecules characteristic of the geminivirus family, and are approximately 18x30mm in size. They envelope a single molecule of single strain DNA composed of 2787 nucleotides. For transmitting the virus naturally, the whitefly requires at least a few minutes to acquire the virus from phloem tissue of an infected plant. The longer the acquisition period, the higher the concentrate of acquired particles. A latent period follows, when the whitefly is not able to transmit the acquired virus. This latent period lasts about eight hours during which time the virus passes from the whitefly’s mouthparts into its digestive system. The virus passes from the digestive system to the hemolymph, and then enters the salivary glands at the front of the insect’s head. Once the whitefly has acquired the virus, it is able to infect plants throughout its lifecycle. A single whitefly is able to infect diverse types of plants. The number of infected plants increases with the number of whitefly vectors. The symptoms of the disease are typical. However to examine the virus in the plants and in the whitefly, new molecular methods have been developed for identification and verification of various isolates, by using detectors based on viral nucleic acids. Agrotechnical methods, including insect-proof nets and insecticide control, are used to reduce the damage caused by the disease. The most efficient method is the cultivation of resistant or tolerant varieties, some of which are available on the market. Other damaging viruses: Tomato bushy stunt virus (TBSV) TBSV causes stunted growth and leaf chlorosis and necrosis. In severe cases, there is abscission of flowers and small fruit. In developing and mature fruit there can be browning under the calyx and at the bottom of the fruit. The virus, which was first identified in California, is found in the soil, disseminated through water and is mechanically transmitted even by pruning suckers or side-shoots. No specific vector is known. Tomato chlorosis virus (ToCV) This is a new disease. Plants infected with ToCV develop chlorosis in the lower leaves, which spreads to the upper parts of the plant. Damaged plants are less vigorous and produce a low yield. Fruit is small and ripening is delayed. At the end of the 1990s, the disease spread significantly in the Malaga Province in Spain, and caused severe damage to tomato fields. There was widespread infestation of tobacco whitefly in the tomato fields, which transmitted the disease to healthy plants. Tests showed that Bemisia tabaci biotype “Q” was the most common whitefly. Disease TYLCV Tomato yellow leaf curl virus Damage Control TMV Tobacco mosaic virus PVY Potato virus Y Table 27. Viral diseases in tomatoes CMV Cucumber mosaic virus TSWV Tomato spotted wilt virus Infected plants become yellow; leaves become small and curled, growth stops and no fruit set. Period of infection according to the activity of the whitefly. Chemical control of the whitefly that transmits the virus. Use of insect proof nets and cover with UV filtering plastic and use of resistant varieties to the virus. Round spots on leaves and some necrosis, withering of plant branches, malformation and discoloration of fruits, usually green, yellow and red raised rings on the fruit skin. The virus is transmited by aphids causing mosaic spots on leaves which become narrow and curled, especially at the top of the plants. Infected plants produce unmarketable fruits. Brown elongated spots on leaves and fruits. Plants become bushy, yellowish and leaves curl; virus causes discoloration of fruits. Mosaic spots on the leaves and the fruits. An infected plant is generally stunted and causes necrosis on fruits, leaves and stems. Monitoring and reduction of the western flower thrips population which transmits the virus, good sanitation, use insect proof nets; chemical control of the thrips and use of resistant varieties. Use insect proof nets, good sanitation, avoid growth of weeds and other hosts of the virus close to tomato fields. Good sanitation surrounding the greenhouses. Use insect proof nets, protected conditions, sanitation, chemical control of aphids and avoid growth of weeds which can be a host for the virus. Use of resistant varieties; use seeds that are treated for the virus. Use crop rotation in soils infected by TMV. Steam and sterilize equipments and containers and use sanitation before handling the plants.
  • 97. 91 Tobacco mosaic virus on leaves Tomato yellow leaf curl virus PVY on foliage Tobacco mosaic virus on fruit Pepino mosaic potexvirus (PepMV) PepMV was first reported and diagnosed in Peru in 1974, in Solanum muricatum. In 1995, the virus was reported in tomato greenhouses in Holland and South America. The virus in Holland is different from that in Peru, which is without symptoms. In experiments with artificial contamination, the virus infected other solanaceous crops, such as eggplant, pepper and potato. The symptoms of the virus that was discovered in Holland are strongly expressed when temperatures are low, as well as on cloudy days, and disappear in high temperatures and clear days. Symptoms usually appear 2-3 weeks after infection and the disease spreads along the row. Diseased plants appear stunted at the apex or display symptoms similar to those of hormone or herbicide damage. Leaves close to the apex display dark spots, while lower leaves display brown spots. Dark brown spots often spread to the stem and the inflorescence, which result in abscission of the flowers. The browning can also appear on the calyx of mature fruit. Sometimes chlorosis appears on the leaves. Pepino mosaic potexvirus is mechanically transmitted when pruning and treating plants, as it is found on hands, clothing, shoes and tools. British scientists found the virus in roots, and Dutch scientists found it after 90 days in dry vegetative matter. Seed transmission is unlikely. Control is mainly by meticulous sanitation and protection throughout the growing period, starting with the treatment of seeds, production of healthy nursery plants, special care when grafting and the use of protective means by workers, such as frequent changing of work clothes, covering shoes and use of disposable gloves. In the greenhouse, workers continuously inspect the crop to find infected plants, marking them and then carefully removing them. Direct contact with the infected plant is prevented by wearing protective clothing and burning the diseased plants in a special place. Tomato apical stunt (TASVd) Tomato plants infected with TASVd show stunted growth in the upper part of the plant as a result of shortened internodes close to the crown. The leaves in this area are distorted, and mature leaves show crinkling and chlorosis with brittle tissue. Sometimes necrotic spots also appear on the leaves. Vegetative growth is stunted and the fruit size and color is also damaged. TASVd can be transmitted from diseased tomato plants to healthy plants by grafting or mechanical inoculation, and this may be the reason for the pattern of spreading along the crop rows. The incubation period of the disease until the symptoms appear is about two weeks. In tomato plants that were infected in experimental conditions, leaves curled downwards and the plants remained stunted and bushy. It is not clear how the disease reached Israel, and it is also not known how it spreads in nature. Epidemiological research and identification of possible vectors may enable implementation of steps to prevent the disease from spreading to further tomato production areas.
  • 98. 92 Tomato spotted wilt virus on fruit PVY on fruit Tomato spotted wilt virus on foliage Tomato plant infected with TASVd Tomato plants infected with PepMV © Queen’s printer for Ontario, 2001 reproduced with permission
  • 99. 40 PESTS The pests listed in the following table are the most common in greenhouse tomato crops. Most of them also attack other crops. There are other pests, apart from those that appear in the table, that attack many crops, such as mole crickets, cutworm (Agrotis), ants, birds, tobacco thrips, weevil, snails, mice and rats. Any of these can appear and cause damage to the plants during the early growing stages, and in the later stages can damage the plants as well as the fruit. Pest control is chemical, biological and agro-technical. In addition, biological control using predator insects (natural enemies) against tomato pests is widespread. Pest management that includes the various chemical, biological and agro-technical pest control methods is known as Integrated Pest Management (IPM). The use of chemical pesticides is significantly reduced in an IPM regime, without any harm to the yields and quality of the tomatoes. Heat necrosis in TMV-resistant tomato varieties Exposure to heat of 28-30ºC or higher and to high concentrations of TMV causes excess sensitivity in a certain percentage of Tm-2a heterozygotic varieties, which is accompanied by localized death of cells. This is known as hypersensitivity or heat necrosis. This reaction results in necrotic lesions on leaves and fruit. The lesions on the fruit are brown and not aesthetic. Damaged fruit is not marketable. Certain genetic combinations, such as virus- resistant homozygotes, or the addition of other alleles, provide plants with virus resistance and prevent the occurrence. TMV hypersensitivity Table 28. Pests Pest Tobacco whitefly Bemisia tabaci race B and Q Description Damage Season Flying insect 1-2 mm long. Wings covered with a white powdery wax Feeds on leaves and transmits TLYCV virus Spring, summer and autumn Often active in greenhouses all year round Aphids Various species, especially aphis gossypii myzuspercisae 2-3 mm long, green to black, wingless as well as winged species Feeds on leaves that curl as a result. Transmits PVY and CMV viruses. All year round Beet armyworm Spodeptera exigua Caterpillars are green when young and turn gray or brown, up to 3 cm in length. Hairs along the segments. Feeds on leaves in long narrow stips. Spring and Autumn Bollworm Heliothis armigera Green or reddish-brown to dark brown caterpillar, 4 cm long, with lighter stripes along both sides and setae along the back. Feeds on fruit and leaves. Spring, summer and autumn Looper Plusia spp. Caterpillar similar to the Bollworm, light green with light stripes along the sides, up to 3 cm long. Feeds on leaves and sometimes on green and red fruit. Summer, autumn and spring. 93
  • 100. 94 Pest Description Damage Season Small 0.3-0.4 mm red or yellow mite, yellow larvae, adult has 4 pairs of legs, found on the underside of the leaves. Small gray moth up to 8-9 mm long, larva color depends on food it eats. Larva reaches 15 mm length. Tiny elongated mite which can only be seen through magnifying glass, on underside of leaf on stem and fruit stalk. Small yellow 2.4 mm fly, maggots colorless when hatch, becoming orange- yellow, final size 3mm. Adult is narrow and 1.2 mm long. Yellow upper side, back appears dark and front yellow when wings closed. pairs of legs, found on the underside of the leaves. Root Knot Nematode Meloidogyne spp. Spider mites Tetranychus spp. Potato tuberworm Phthorimaea operculella Russet mites Aculops lycopersici Leaf miners Liriomyza trifolii, Liriomyza huidobrensis Microscopic, female usually round and male long and threadlike. Galls form in roots; when infection is heavy, plants wither and die. Scratches the leaf cuticle and then feeds on leaves, usually on the underside, creating silvery-gray spots, leaves dry up. Larvae develop on leaves, worms then move to fruit, entering under the sepal and burrowing under stalk into fruit. Leaves and stalks green/dark-brown, ust- like, leaves dry up. Maggots burrow tunnels in leaves, reducing photosynthetic area, secondary leaf disease infection such as early blight and grey mold (Botrytis cinerea) Found in flowers and plant tops. Could cause malformed fruit and transmit TSWV virus. All year round (for more details - page 34). All year round - intensified in dry weather. Spring, summer and autumn Spring and summer, intensifies in dry weather All year round Western flower thrips Frankliniella occidentalis Young caterpillar is green and turns dark gray or brown-black. The body segment closest to the head has two dark spots, the adult also has these spots at the back. Egyptian leaf worm Spodoptera littoralis Feeds on all parts of the plant. Summer and autumn Black cutworms, adult caterpillers are large brown or gray, mature larvae about 4 cm long. Cutworms spend winter as larvae in the soil, there are several generations each year. Cut crowns of young plants, active at night and hide during the day underneath plants below the soil surface. Spring and autumn. Intensifies in soils rich in fresh organic matirial. Cutworms Agrotis Spp. All year round
  • 101. 95 Red spider mite damage on leaves Russet mites damage on fruit Russet mite damage on foliage and fruit Red spider mite damage on fruit Yellow spider mitesRed spider mites Looper - plusiaCotton worm
  • 102. 96 Bemisia tabaci - tobacco witefly Leaf miner - Adult Pupa of leaf miner Adult and caterpiller of potato tuberworm Infection by potato tuberworm Leaf miner injury Western flower thrips
  • 103. BibliographyBIBLIOGRAPHY 1. Banuelos, G. S., Offermann, G. P., and Seim, E .C. 1985. High relative humidity promotes blossom-end rot on growing tomato fruit. HortScience 20 (5), pp. 894-895. 2. Benton Jones Jr., J. 1998. Tomato Plant Culture: In the Field, Greenhouse, and Home Garden. 3. Burnham, T. J. 1997. Storage for tomatoes. The Grower, pp. 33-34 (March). 4. Den Outer R.W. and Van Veenendaal W.L.H. 1998. Gold Speckles and Crystals in Tomato Fruits. Department of Plant Cytology and Morphology, Agriculture University Wageningen, The Netherlands 5. Kretchman, Dale. 1990. Tomato disorders are preventable. American Vegetable Grower. 6. Navas-Castillo J., Camero, R., Bueno M. and Moriones E. 2000. Severe yellowing outbreaks in tomato in Spain associated with infection of chlorosis virus. Experimental Station, Malaga, Spain, Plant Disease, Vol. 84, No. 8, pp 835-837. 7. Ohta Katsumi. 1993. Influence of the nutrient solution concentrations on cracking of cherry tomato fruit grown hydroponically. Japan Soc. HortScience 62 (2); pp 407-412. 8. Peet M. M., Gipson J .L., Whipker B. E. and Blankenship S. 2000. Ethylene damage, what it is and how to prevent it, The Tomato Magazine, pp 16-20 (April). 9. Rylski, I., Shan, S. 1988. Effect of plant growth regulators on tomato fruit set and fruit growth under high temperature conditions, First Annual Report, Agriculture Research Organization, Volcani Center. 10. Sonneveld C. 1987. Magnesium deficiency in rock wool grown tomatoes as affected by climate conditions and plant nutrition. Journal of Plant Nutrition (9-16), pp 1591-1604. 11. Stevens and Rick. 1986. Genetics and breeding in Atherton and Rudich. The Tomato Crop. 12. Winsor, G. and Adams, P. 1987. Diagnosis of minimal disorders in plants. Volume 3, Glasshouse Crops. London: Her Majesty’s Stationary Office. 13. Wisler, G. 2000. A new disease is spreading. Greenhouse Insider 97
  • 104. 98 List of Hebrew SourcesLIST OF HEBREW SOURCES Ʊ˙‡ϘÁ·†ÌȘ¯Ù†≠†˙Èχ¯˘È‰†˙È‚¯Â‡‰†˙‡ϘÁ·†ÌȘÂÁ†ÌÈÁ˜ÈÙ†¨ÌÈ˜˙†®≤∞∞¥©†Æ‡†¯Ï„‡ Ʊ≤≠±¥†ÌÈ„ÂÓÚ†˙„ÂÒȆү˜φ˙¯·ÂÁ†˙È‚¯Â‡‰ Æ≤Ï˘†Ë¯Ëȇ‰†¯˙‡†≠†‰ÁÈÓˆ†È˙··†˙È‚¯Â‡†˙ÂÈ·‚چτȂφ˙ˆÏÓ‰†®≤∞∞¥©†Æ‡†¯Ï„‡ ÆÈ‚¯Â‡‰†Ô‚¯‡‰ Æ≥±∑µ†≠†Â†±¥¥†ÌÈʉӆ‰ÓÓÁ†˙ÂÈ·‚Ú†˙·Â‚˙†®±ππ≤©†ªÆÚ†ÛÒ‡†¨Æ‡†ıȷ˜·Ï†¨Æ‡†Ô˙Ó†¨Æ·†ÛÒÂȆ¯· Æ¯Â˘·‰†¯Âʇ·†ÔÂ˘È„Â†‰È˜˘‰Ï Æ¥Æ¯Â˘·‰†¯Âʇ·†‰ÓÓÁ†˙ÂÈ·‚Ú†˙Ș˘‰Â†ÔÂ˘È„†®±π∏∞©†ªÆ‡†Â‰Èχ†¨Æ·†·È‚˘†¨Æ·†ÛÒÂȆ¯· Ƶ‰„˘†ÈÈÂÒÈ†Ìȯ˜ÁÓ†ÌÂÎÒ†≠‰ÁÈÓˆ†˙È··†˙ÂÈ·‚Ú·†ÌÈÓ†¯ÂÊÁÈÓ†®≤∞∞≤©†ªÂȯ·ÂÁ†Ʒ†ÛÒÂȆ¯· Ʊ≤±≠±≥∂†ÌÈ„ÂÓÚ†≤∞∞±Ø≤†Ï·ӆ˙ÂÈ·‚Ú· Æ∂‰˜ÏÁÓ‰†˙‡ˆÂ‰†ÆÔ˙¯·„‰Â†Ô˙ÂÁ˙Ù˙‰†¨ÌÈÙ¢‰†˜¯È‰Â†È¯Ù‰†˙ÂÏÁÓ†®±ππ∑©†ª†Æ¯†ÔÏ‚≠ȇ˜¯· ÆȇϘÁ‰†¯˜ÁÓ‰†Ï‰Ó†¨ÌÈÈÚ„Ó†ÌÈÓÂÒ¯ÙÏ Æ∑Æχ¯˘È·†˙˜ÏÚ†®≤∞∞≥©†ª†Æ˘†„ÏÙÈϘ†¨È†¯Ò„Ï‚ Æ∏‰Î¯„‰‰†˙Â¯È˘†˙‡ˆÂ‰†¨‡ÂˆÈφÈÓ˜Ӊ†˜Â˘Ï†Ï·ӆ˙ÂÈ·‚چτȂ†®±π∏µ©†ª†ÆÁ†‚¯·ÊÈ‚ ƯÙΉ†ÁÂ˙ÈÙ†˙‡ϘÁ‰†„¯˘Ó†¨Úˆ˜Ó‰Â ÆπÏ˘†˙·Ï¢ӆ‰¯·„‰†®±ππ𩆪Æچχ„ӆ¨Æ‡†Â˜Â‡†¨ÆȆÔ˘†¨Æ†‚¯·ÏÈʆ¨Æ‡†ÔÈÈˢȯ‚†¨Æ‡†Ï‡ÈÏÓ‚ ±ππ∏Øππ†¯˜ÁÓ‰†˙ÂÚ†ÌÂÎÈ҆Ɖ·¯Ú·†˙˜¯È†ÈÏ„Ȃ·†„ÈÓ¯·†ÏÈ˙Óφ˙ÂÙÂÏÁ≠Ú˜¯˜†Èڂ٠Ʊ∞≠≤±†ÌÈ„ÂÓÚ†˙ÈÂو†‰ÂÎÈ˙†‰·¯Ú†Ù¢ÂÓ Æ±∞ÌÈÚ‚Ù†˙¯·„‰Ï†¯ÂËȘ·†Ú˜¯˜†ÈÂËÈÁ†Ì¢ÈȆ®≤∞∞≤©ª†ÆȆ‰˜ÈÒÓ†¨ÆÓ†ÔÓ¯‚ȯˆ¨Æ‡†Ô˙Ó†¨Æ‡†Ï‡ÈÏÓ‚ Ʊ∑±≠±∏∞† ÌÈ„ÂÓÚ† ≤∞∞±Ø≤† ̯„† Ù¢ÂÓ† ‰ÂÚ† ÌÂÎÒ† ¨®≤∞∞∞©† ‰ÓÓÁ·† ˙ÂÈ·‚Ú· Ʊ±Ìȯ˜ÁÓ†ÌÂÎÒ†≤∞∞∞ر†˘ÈÎφ˙ÂÈ·‚Ú·†˙·ί‰†ÔÁ·Ó†®≤∞∞±©†ªÆÚ†Ô‡„Èʆ¨Æ˘†Ô˙„†¨Æ˘†ı‚ Æπµ≠±∞¥†ÌÈ„ÂÓÚ†≤∞∞∞ر†˙˘Ï†˙ÂÈ·‚Ú·†‰„˘†ÈÈÂÒÈ Ʊ≤ÌÂÎÒ†¨˙ÂÈ·‚Ú·†„ÈÓ¯·†ÏÈ˙Óφ˙ÂÙÂÏÁ†˙ÈÁ·†®≤∞∞≤©†ªÆ˘†Ô˙„†¨ÆÚ†Ô‡„Èʆ¨ÆȆҘʆ¨Æ˘†ı‚ Æππ≠±∞≥†ÌÈ„ÂÓÚ†≤∞∞±Ø≤†Ï·ӆ˙ÂÈ·‚Ú·†‰„˘†ÈÈÂÒÈ†Ìȯ˜ÁÓ Æ±≥ÆÏ·ӆ˙ÂÈ·‚Ú·†„ÈÓ¯·†ÏÈ˙Óφ˙ÂÙÂÏÁ†˙ÈÁ·†®≤∞∞≥©ªÆȆÔÂÏÁΆ¨ÆÚ†Ô‡„Èʆ¨ÆȆҘʆ¨Æ˘†ı‚ Ʊ±±≠±±∏† ÌÈ„ÂÓÚ† ≤∞∞≤Ø≥† Ï·ӆ ˙ÂÈ·‚Ú·† ‰„˘† ÈÈÂÒÈ† Ìȯ˜ÁÓ† ÌÂÎÒ Æ±¥ÆÚ„Ó·†ÌÈÓÂÒ¯ÙφÔӈȆ„ÒÂÓ†˙‡ˆÂ‰·†Ï‡¯˘È·†ÌÈÁÓˆ·†ÌȘ„ÈÈÁ†˙ÂÏÁÓ†®±π∏µ©†ªÆˆ†È˜Ï Æπ±∞∞∑†ÌÈÏ˘Â¯È†∏∞±†Æ„Æ˙ ƱµÆßȆ˙¯·ÂÁ†¨·¢Ú†Í¯Î†¨‰„˘‰†¨˜˙ÂÓ†ÚˆÓ·†˙ÂÈ·‚چτȂ†®±ππ≤©†ªÆ‡†Ô„È·‡†¨ÆÚ†Ô‡„ÈÊ Æ±∂Æ˙˜¯Èφۂ‡‰†¨Úˆ˜Ó‰Â†‰Î¯„‰‰†˙Â¯È˘†¨‰ÁÈÓˆ†È˙··†˙ÂÈ·‚چτȂ†®±ππ≥©†ªÆÚ†Ô‡„ÈÊ Æ±∑„¯˘Ó†¨Úˆ˜Ó‰Â†‰Î¯„‰‰†˙Â¯È˘†¨±π∏πØπ†˙˘Ï†‰„˘†ÈÂÒÈ·†¯˜ÁÓ†ÌÂÎÈÒ†®±ππ𩆪ÆÚ†Ô‡„ÈÊ Æ¯ÙΉ†ÁÂ˙ÈÙ†˙‡ϘÁ‰ Ʊ∏ËÒ‚‡†Ó¢‰˘†˙‡ˆÂ‰·†˙ˆÏÓ‰†ÔÂÙ„†–†‰ÁÈÓˆ†È˙··†Ï·ӆ˙ÂÈ·‚Ú†Èʆ®≤∞∞≥©†ªÆÚ†Ô‡„ÈÊ Æ≤∞∞≥ Ʊπ˙‡ϘÁ‰†„¯˘Ó†¨Úˆ˜Ó‰Â†‰Î¯„‰‰†˙Â¯È˘†¨˙˜¯È·†ÌÈÚ‚Ù†˙¯·„‰Ï†˙ˆÏÓ‰†®≤∞∞≤©†ªÆÈ†Ò˜Ê Æ¯ÙΉ†ÁÂ˙ÈÙ Æ≤∞¨±ππ∞†·Èˆ˜˙‰†˙˘Ï†ÌÎÒÓ†Á„†¨ÌȘ˙ÂÓ†ÌÈÚˆÓ·†˙˜¯È†Ï„Ȃ†˙ÈÁ·†®±π𱩪†ÆȆ¯·Ú†¨ÆȆÔÁ Ɖ·¯Ú†Ù¢ÂÓ†˙˜¯È‰†ÛÚ†˙ω‰Ï†˘‚ÂÓ
  • 105. 99 Æ≤±ÌÈ˘„Á†ÌȯˆÂÓ†˙ÈÁ·†®≤∞∞≥©†ªÆ˘†ÈÏȇ†¨Æ‚†Û˘¯†¨ÆÚ†Ô‡„Èʆ¨Æ¯†„È·¯†¨Æ‡†˙ÙȆ¨Æ˘†„„†¨ÆÁ†Ï‡˜ÊÁÈ Æ≤≥≠≥∏† ÌÈ„ÂÓÚ† ≤∞∞≤Ø≥† Ï·ӆ ˙ÂÈ·‚Ú·† ‰„˘† ÈÈÂÒÈ† Ìȯ˜ÁÓ† ÌÂÎÒ† ¨˙ÂÈ·‚Ú· Æ≤≤‰˜ÏÁÓ‰†˙‡ˆÂ‰†¨Ï‡¯˘È·†ÌÈÁÓˆ†˙ÂÏÁÓ†®±ππ∏©†ª˙ÙȆԷ†˙ÙȆÈËÏÙ†ÛÒÂȆ¨Ì˙¯†ÛÒÂÈ ÆÔ‚„†˙È·†¨È˜Ï†Êίӆ¨ÌÈÈÚ„Ó†ÌÈÓÂÒ¯ÙÏ Æ≤≥˜˙ÂÓ†ÚˆÓφ‰¯˜·Â†ÔÂ˘È„†¨‰È˜˘‰†˙ίÚÓ†˙È˙˘˙†˙Ήφ˙ÂÈÁ‰†®±ππ∏©†ª‰È¯‡†˜ÁˆÈ Ɖ„˘†˙Â¯È˘†Û‚‡†¨Úˆ˜Ó‰Â†‰Î¯„‰‰†˙Â¯È˘†¨‰ÁÈÓˆ†È˙·· Æ≤¥ÌÈÓÂÒ¯Ùφ‰˜ÏÁÓ‰†˙‡ˆÂ‰†¨Ì¢ÈȆ˙Â¯˜Ú†¨ÌÈÁÓˆ†Ï˘†‰È‚ÂϯȆ®±ππ≥©ª†„‚†ÔÈÈˢ·ÂÏ ÆÔ‚„†˙È·†¨È˜Ï†Êίӆ¨È‡Ï˜Á‰†¯˜ÁÓ‰†Ï‰Ó†¨ÌÈÈÚ„Ó Æ≤µ˙ÂÈ·‚Ú†ÔÂÒÁ‡·†Ìȯ˜ÁÓ†¨˙ȇϘÁ†˙¯ˆÂ˙†¯˜Áφ‰˜ÏÁÓ‰†Á¢Â„†®≤∞∞≥©†ªÂȯ·ÂÁ†Ƈ†¯ËÎÈÏ Æ±∏≥≠±π∂† ÌÈ„ÂÓÚ† ≤∞∞≤Ø≥† Ï·ӆ ˙ÂÈ·‚Ú·† ‰„˘† ÈÈÂÒÈ† Ìȯ˜ÁÓ† ÌÂÎÒ† Æ≤∞∞≤Ø≥ Æ≤∂Æȯˆ ‡ÂˆÈÈφ ˙„ÚÂÈÓ‰† ˙ÂÈ·‚Ú† ÔÂÒÁ‡·† Ìȯ˜ÁÓ† ®±ππ∏©† ªÂȯ·ÂÁ† ̯ÂȆ Ò˜ÂÙ Æ≤∑Æχ¯˘È·† ÛÈ˘φ ÌÈ„¯Â† ÈÏ„Ȃφ ÈÚˆ˜Ó† Íȯ„Ó† –† „¯Â‰† ͯ„† ®±ππ𩆠ªÌÈÒÈ† ÒÈÙ Æ≤∏‰È˜˘‰†˜˘ÓÓ†˙ÂÚˆÓ‡·†‰ÓÓÁ†ß‚Ú†˙ÂÎȇ†ÏÂ·È†Ï˘†‰ÙÂÏÁ˙†®±ππ∂©†ªÂȯ·ÂÁ†ƈ†Ë‡ÏÙ ÆÌÈÁÈÏÓ†ÌȯÈÙ˘†ÌÈÓ· Æ≤π˙ÈÏÓ˘Á†‰¯Â·„Ó†‰ÏÈÚȆ¯·†˙¯Â·„†®±ππ≤©†ªÆ‡†‰˜ÒÏȯ†Æ¯†„˜˘†¨Æ˜†„ÏÙʯ†¨Æ‡†ÔÓÒ¯Ù Æ·†˙¯·ÂÁ†¨‚¢Ú†Í¯Î†¨‰„˘‰†¨‰ÓÓÁ†ß‚چȯن˙˜·‡‰· Æ≥∞‰„˘†ÈÈÂÒÈ†Ìȯ˜ÁÓ†ÌÂÎÒ†¨˙ÂÏÂ΢‡·†˙ÂÈ·‚Ú†ÛÚ†ÁÂ˙ÈÙ†®≤∞∞±©†ªÂȯ·ÂÁ†Ƈ†ÔÓÒ¯Ù Æ∏±≠∏∏†ÌÈ„ÂÓÚ†≤∞∞∞ر†˙˘Ï†˙ÂÈ·‚Ú· Æ≥±‰ÙÈˢ†˙¯ÊÚ·†ÛÈ˘‰†¯Á‡Ï†˙Âȯˆ˙ÂÈ·‚Ú†˙ÂÎȇ†¯ÂÓÈ˘†®≤∞∞≤©†ªÆ˘†ÈÚϘχ†¨Æ‡†˜ÈÏ٠ƥ±≠¥≥† ÌÈ„ÂÓÚ† ≤∞∞≤† ËÒ‚‡† ¨˜˘Ó† ‰„˘† Ô‚† ƉÒÁ‡‰† ÈÙφ ‰ÓÁ† ‰˘¯·‰Â Æ≥≤Æ≤±≤≠≤∂∞†ÌÈ„ÂÓچ߇†˙˜¯È†¨˙‡ϘÁφ‰È„ÙÂϘˆȇ‰†®±π∏𩆪†ÆÁ†‚¯·ÊÈ‚†¨Æ†¯„Ș Æ≥≥Æ˙ÂÈ·‚Ú† ÏÚ† ϯ˙‡† ˙ÚÙ˘‰·† Ìȯ˜ÁÓ† ®±π∑±©ª† Æ† ¯„Ș† ¨Æ·† ˜È„¯† ¨Æ‡† ¯ËϘ Æ≥¥‰È·‚Ú‰†È¯Ù†Ï˘†‰ÏÈ„‚‰Â†‰ËÁ‰†˙¯·‚‰†®±π∏∞©ª†ÆÁ†Ì‰¯·‡†¨Æ„†¯È‰†¨Æ˘†¯ÂÓ†Ô‚†¨Æ‡†‰˜ÒÏȯ ¨„ÁÂÈÓ†ÌÂÒ¯Ù†¨È‡Ï˜Á‰†¯˜ÁÓ‰†Ï‰ÈÓ†¨‰ÁÈÓˆ†È¯ÓÂÁ·†ÒÂÒȯ†˙ÂÁ¯Ù˙†¯ÂÚÈ†˙¯ÊÚ· Ʊ∑∏†¯ÙÒÓ Æ≥µ‰Î¯„‰‰†˙Â¯È˘†¨¯‰‰Â†‰ÏÙ˘‰†ÊÂÁÓ·†Ú˜¯˜·†Ï„Ȃ·†˙˜¯È†˙ÈȘ˘‰Â†ÔÂ˘È„†®≤∞∞∞©†ªÆ‚†Û˘¯ Ɖ„˘†˙¯˘†Û‚‡†¨Úˆ˜Ó‰Â Æ≥∂˙ÂÁ˙Ù˙‰‰†ÏÚ†‰Áȯى†ÏÚ†‰ȯ˜‰†˙ÓˆÂÚ†˙ÚÙ˘‰†®±π∑𩆪ÆÓ†Ò˜ÂÙ†¨Æ‡†‰˜ÒÏȯ†¨Æ‡†‡È‚˘ Æ≤∞∏†¯ÙÒÓ†ÔÈËÏ·†¨ß‚Ú·†È¯Ù‰†Ï˘