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High tunel tomato production m00170


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High tunel tomato production m00170

  1. 1. ContentsAuthorsLewis W. Jett, Department of Horticulture, University of Frequently asked questions about high tunnels 1 Missouri-Columbiain collaboration with Constructing a high tunnel 4David Coltrain Kansas State University Producing tomatoes in a high tunnel 7Jay Chism, James Quinn, and Andrew Read High tunnel temperature management 13 University of Missouri-Columbia Cropping systems for tomatoes in high tunnels 15Editorial staffMU Extension and Agricultural Information High tunnel tomato pest management 17 Dale Langford, editor Dennis Murphy, illustrator Marketing & economics of high tunnel tomatoes 21On the World Wide Web Appendix: Sources of supplyFind this and other MU Extension publications on the Drip irrigation supplies 26World Wide Web at Tomato seed 26 High tunnels 27Photographs Biological pest controls 27Except where noted, all photographs are by Lewis W. Jett.AcknowledgmentsResearch reported in this publication was funded in partby a grant from the Initiative for Future Agriculture andFood Systems (IFAFS), U.S. Department of Agriculture.Thanks are due to Mr. Tim Reinbott, supervisor of theUniversity of Missouri Bradford Research and ExtensionCenter for his assistance with this research. For further information, address questions to Dr. Lewis W. Jett College of Agriculture Extension State Vegetable Crops Specialist Food and Department of Horticulture Natural Resources University of Missouri Columbia, MO 65211 Copyright 2004 by the University of Missouri E-mail: Board of Curators
  2. 2. Frequently Asked Questions About High TunnelsWhat is a high tunnel? ary unit, you will need to amend the soil each A high tunnel is a solar-heated, plastic- season or year with compost or other organiccovered greenhouse with no electrical or auto- sources to maintain soil quality and fertility.mated ventilation. It can be used to extend thecrop production season for many horticultural When can I plant vegetables in a highcrops. Crops that are produced within high tun- tunnel?nels are grown in the ground with drip Placing a high tunnel on your farm isirrigation. roughly equivalent to raising the average annu- al air temperatures in your area by 10–15Where can I purchase a high tunnel? degrees F. Therefore, you can schedule plant- There are several manufacturers of high ing based on field planting dates in the USDAtunnels. See the Appendix for a list of high tun- hardiness zone directly south of your farm. Seenel manufacturers. inside back cover for zone map.How much does a high tunnel cost? Should I grow vegetables in a High tunnels can be built at a cost of about greenhouse or a high tunnel?$0.75 to $1.50 per square foot. This includes Input costs for greenhouse vegetable pro-the frame structure and the plastic cover. As a duction are significantly higher than those forrule of thumb, you should expect to pay at least high tunnel vegetable production. Greenhousean additional 25 percent for end wall lumber, establishment costs approximate $6 per squaresite preparation, water lines and other acces- foot, almost five times the cost of a high tunnel.sories. Do I need a building permit for myWhat are the typical dimensions of a high tunnel?high tunnel? Generally speaking, high tunnels are con- Dimensions of a commercial high tunnel sidered to be nonpermanent structures.range from 10 to 30 feet wide by 9 to 12 feet However, you may need to check with yourhigh by 96 to 100 feet long. local zoning regulations.Where should I place a high tunnel on What is the optimal orientation for amy farm? high tunnel? A high tunnel should be placed on a level, When orienting a high tunnel, in contrastwell-drained, accessible site. High tunnels can to a greenhouse, sunlight is less important thanbe moveable, but if you wish to have a station- good ventilation. A high tunnel should be ori-College of Agriculture, Food and Natural Resources
  3. 3. 2 High Tunnel Tomato Production Guide ented in a direction that is perpendicular to the Other choices include peppers, summer squash, prevailing winds on your farm. Remember, all cucumbers, melons, herbs, eggplant, and snap ventilation is manual, so you depend on the or pole beans. wind to ventilate your house. Generally, for locations south of 40 degrees What are some examples of cropping north latitude (central Illinois, northern patterns for a high tunnel? Missouri, southern Nebraska), high tunnels At least two crops per year can be produced should be oriented north–south. This orienta- using a high tunnel. In central Missouri, for tion maximizes light interception and is per- example, tomatoes can be planted as early as pendicular to the prevailing westerly winds. March within a high tunnel, and harvest can begin in mid-June. Depending on the variety Should I use a single or double layer of and type of tomato chosen, harvest can con- plastic for my high tunnel? tinue through July. At this point, the tomatoes A double layer of plastic will almost double can be removed, the soil fertilized and tilled, the insulation properties of the high tunnel. and a second crop of peppers, cucumbers or However, adding another layer of plastic beans can be established for fall harvest. If you reduces light intensity. An inflation fan will be wish to keep tomatoes in the high tunnel, needed to blow air into the area between the spring-planted tomatoes will bear fruit through two layers to reduce moisture buildup and October in Missouri. A cool-season vegetable increase the insulation properties of the cover. can be planted in late November and then be The outer layer of plastic is 6 mil and the inner either harvested or overwintered in the high layer is typically 4 mil. tunnel. Can a high tunnel be mobile? How are tomatoes grown within a Yes. One of the primary objectives of a high high tunnel? tunnel is to lengthen the harvest period. Tomatoes are grown on raised beds with Movable high tunnels may be relocated to organic or plastic mulch. The raised bed (at existing plots of cropland to accelerate early least 6 inches high) will facilitate drainage and growth or extend the growing season for that keep the root system warmer. Plastic mulch crop. However, they are less airtight than sta- (black, clear, or infrared-transmitting) will also tionary high tunnels. Consult Eliot Coleman’s increase soil temperatures. Drip irrigation is Winter Harvest Manual for additional informa- used to water and fertilize the tomatoes tion on design of movable high tunnels. through the growing season. Row covers, a lightweight fabric, must be used to provide What type of plastic is used to cover a early frost protection. The tomatoes can be high tunnel? either staked or caged. Six-mil, four-year, greenhouse-grade poly- ethylene is a suitable material for covering a How many tomatoes can I plant in a high tunnel. 20 x 96 high tunnel? The optimal spacing for tomatoes in a high How high should the sidewalls be for a tunnel is 6 square feet per plant. Therefore, high tunnel? approximately 300 plants can be planted per A sidewall 5 feet high is superior to a 3-foot house. sidewall with respect to air circulation. For tomatoes, a sidewall at least 5 feet high will per- Is pollination of tomatoes adversely mit air to move above the crop canopy. affected by the high tunnel? No. Tomatoes are self-pollinated. Research What warm-season vegetables can be at the University of Missouri has shown no pol- produced in a high tunnel? lination problems with tomatoes in a high tun- Warm-season vegetables are sensitive to nel. Air movement, which reduces humidity frost. Many types of vegetables can be grown and vibrates the flower, is important for good successfully in a high tunnel. Many growers pollination. If you have to keep the vents closed have used high tunnels for early tomatoes. for an extended period, you may want to shake University of Missouri Extension
  4. 4. 3 Frequently Asked Questionsthe cages or stakes to facilitate pollination. If Can I use pesticides within a high tunnel?you are using row covers, they should be Some pesticides can be used within a highremoved when the plants are flowering and the tunnel, but growers must read the label specifi-sidewalls are rolled up. If temperatures are pro- cally for each crop. Current regulations main-jected to fall to 55 degrees F or less, the row tain that when high tunnel sidewall vents arecovers should remain on the plants. High side- rolled up, the high tunnel may be treated as awalls improve cross-ventilation within the high field crop. Opening just the end walls is not suf-tunnel. ficient for applying pesticides within a high tunnel. When the sides are down, the high tun-What is an average yield for high nel should be treated as a greenhouse. Keep thetunnel tomatoes? sidewall vents open for the length of the reentry High tunnel tomatoes average about 10–12 interval (REI).pounds of tomatoes per plant over a four-weekharvest period (mid-June to mid-July). The Are certain tomato cultivars bestpercentage of unmarketable fruit is much lower suited for high tunnel production?for high tunnel tomatoes than for field Any field or garden tomato will performtomatoes. well in a high tunnel. If the objective is to pro- duce early tomatoes, the best choice would be aDo I need to spray tomatoes in a high hybrid, determinate cultivar that concentratestunnel for disease and insect control? its fruit-set within a narrow window (4–6 High tunnels provide a protected environ- weeks). Indeterminate types will perform wellment for crop growth. However, this does not in a high tunnel. However, these types of toma-mean that you will not have any harmful dis- toes continue to set fruit through the summereases or insects. Protecting the crop from rain and fall and will not yield a large quantity ofwill significantly reduce disease problems. fruit per harvest. Indeterminate tomatoes areHowever, you should scout your crop for any well suited for late summer and fall tomatoes.sign of disease. Pay close attention to the rowsnearest the baseboards or doors. Insects Can high-bicarbonate irrigation waterencountered on tomatoes in the Universitiy of be a problem for high tunnel tomatoes?Missouri high tunnel trials include aphids Using irrigation water that is high in calci-(Myzus persicae), hornworms (Protoparce quin- um and magnesium can increase the pH of thequemaculata) and fruitworms (Helicoverpa zea). soil over time and cause nutrient imbalances.Many of these insects can be controlled by bio- Test the water for pH and bicarbonate levels.logical methods (beneficial insects) or using Using sulfur fertilizers or injecting acids intobiological insecticides (Bt insecticides) or by irrigation water can neutralize the bicarbonates.exclusion (closing vents at night). For more information about high tunnels Coleman, Eliot. 1998. The Winter Harvest Manual. (Four Season Farm, 609 Weir Cove Road, Harborside, ME 04642) Web site for the Central Great Plains High Tunnel Collaborative Project Pennsylvania State University Web site for high tunnel horticulture research Noble Foundation high tunnel research projectsCollege of Agriculture, Food and Natural Resources
  5. 5. 4 High Tunnel Tomato Production Guide Constructing a High Tunnel High tunnels are solar-heated, plastic- sandy loam soil. Deep soil facilitates the forma- covered structures that provide a protected tion of raised beds; tomatoes have a large root environment for high-value crops. These pro- volume requiring deep, well-drained soils. Do tective structures consist of a series of evenly not place the high tunnel in a frost pocket spaced bows that provide structural support for where either air or water drainage is a problem. the polyethylene covering. Most commercial Make site adjustments to allow for surface units are available in widths ranging from 14 to water runoff. Drainage pipe can be buried 30 feet, and may vary from 48 to 96 feet long. around the perimeter of each high tunnel to At the University of Missouri, a “Polar” high prevent water from seeping into the structure. tunnel kit was purchased from Stuppy Select a parcel of land that is larger than what is Greenhouse Manufacturing, Inc. (Kansas City, immediately needed to allow for expansion if Mo.). The dimensions of this structure are 20 necessary. Additional areas may also be needed feet wide by 12 feet high with bows spaced four to accommodate service or storage buildings. feet apart and 5-foot high sidewalls (Figure 1). Care should be taken to avoid locations where This structure can be up to 100 feet long. trees or buildings may cast shadows on the solar-heated structures. Selecting the site High tunnels should be oriented to facili- The first step in constructing a high tunnel tate good air movement across the structure. is site selection. The site should be relatively For maximum light interception, high tunnels level to reduce the cost of grading. If possible, above 40 degrees north latitude (northern select a site that has deep, well-drained loam or Missouri) should be oriented east–west. For locations below that line, north–south is the optimum orientation. The deciding factor should be prevailing wind direction on your farm. The long axis of the high tunnel should be perpendicular to prevailing winds during spring and summer. Cold, winter winds from the northwest should contact the end wall. Windbreaks on the north sides of high tunnels may be applicable in some areas. Access to the high tunnel is also important when considering location. Because high tun- nels require manual labor to vent, the structuresFigure 1. High tunnel components include sidewall, end wall, bows and purlin. should be in a convenient location to minimize labor cost. Construction Side posts Begin constructing your high tunnel by at 4- or 6-foot spacing positioning and squaring the four corner posts. Guide strings after Use a hand-held level to make sure the posts moving out half the diameter are set vertically in the ground. To check for a of the column square layout of the corner posts, measure each Diagonal measure diagonal. The lengths of the two diagonals should be within half an inch of each other. Use the Pythagorean theorem to set the high tunnel square: the square of the diagonal Batten boards should equal to the sum of the squares of the two sides of the high tunnel. The diagonal of aFigure 2. Design layout for high tunnel. (Source: Nagengast, 2003). 20 x 96 high tunnel is 98.06 feet. Measuring University of Missouri Extension
  6. 6. 5 Constructing a High Tunnelthis distance for both diagonals will ensure that structure, there may beyour corner posts are set 90 degrees to each one to four purlins perother. You may wish to cement the corner posts tunnel (Figure 4).to add structural integrity to the high tunnel.Set all posts to a depth of 24 inches. Metal posts Baseboard and hipcan be driven into the ground by using a metal board installationfence post driver or by placing a trailer hitchball on top of the post to protect the post ends Baseboards fastenedand striking the ball with a heavy hammer. to the support posts Run a string line from one corner post strengthen the founda- Figure 5. Baseboard and hip board attached to sidedown the long axis of the tunnel to the corner tion of the high tunnel. on the other end, drive the remaining side A 2" x 6" pressure-treat-posts in the ground to the proper depth (Figure ed board makes a good2). The top of each post should be the same dis- baseboard for mosttance from the string line to ensure the proper applications. Use post ordepth and to keep the bows level. conduit clamps to attach the baseboard to theInstalling the bows side posts (Figure 5). Most manufactured high tunnel bows are Hip boards adddelivered in two or three pieces. Stuppy’s strength to the tunnel“Polar” unit is delivered in three sections. and serve as a top point Figure 6. Plastic attached to hip board.Assemble a bow by joining two bow sections for rolling up the side-with a ridge connecter to form an arch. Attach walls. Hip boards should be located 5 feet abovethe complete bows to the side posts. At least two the baseboards for maximum ventilation.people are needed to insert the bows into the Attach the hip board in the same manner as theside posts. After the bows are in place, the cen- baseboard. Then attach a 1" x 3" board alongter purlin can be attached to each bow with a the top of the hip board. This will serve as thepurlin bracket (Figure 3). The center purlin sits attachment point for the polyethylene cover-on top of the bows in the Stuppy “Polar” design, ing. Pull the polyethylene over the 1" x 3"but some manufacturers’ purlins will be board and then install another 1" x 3" board toattached under the high tunnel bows. Additional sandwich the plastic film between the twopurlins may be added to give extra stability to boards (Figure 6).the high tunnel. Depending on the width of the End wall construction End wall designs are numerous (Figure 7). University of Missouri Research High Tunnels are framed so that end wall panels can be removed. Removable end walls allow larger equipment, such as utility tractors, to be oper- ated inside the tunnel (Figure 8). Four 8 x 8 panels are installed on each tunnel. It is alsoFigure 3. A purlin bracket (left) is used to connect the necessary to construct a storage rack near thetwo bow sections. The center purlin of the Stuppy tunnel locations to allow for easy storage of the“Polar Cub” design (right) sits on top of the bows .Figure 4. Purlins can number from one to four on a Figure 7. Various end wall designs used on commercial high tunnels.high tunnel.College of Agriculture, Food and Natural Resources
  7. 7. 6 High Tunnel Tomato Production Guide panels when they are plastic to the 2" x 6" hip removed for the sum- board with the 1" x 3" mer months (Figure 9). boards. The cover Attached to each panel should come over the are two handles that top of the upper 1" x 3" make the panels easier board and under the to lift. Each panel is other board as previous- held in place by four ly described. Keep the Figure 10. Wiggle (zigzag) modified angle-iron plastic tight as you wire is used to secure the gate latches (Figure 8). secure the covering. plastic to the frame. The edge of the During end wall angle iron attached to construction, attach aluminum channel lock on the end wall framing top of the two end wall bows. This channel was ground down to allows the plastic covering to be attached to the make the panels easier bows by using a 13-gauge, high tensile wireFigure 8. End wall panels are held in place by modi- to remove. called wiggle wire, which locks the polyethyl-fied angle-iron brackets. ene in place (Figure 10). Covering the high Attach the sidewall plastic to a 3⁄4"-diameter tunnel PVC pipe to allow the sidewalls to be rolled up (Figure 11). Attach the sidewall plastic to the Plastic films for roll-up pipe with a second PVC pipe that has covering high tunnels been ripped in half and screwed to the roll-up should be 6-mil green- pipe. house-grade plastic with UV light resistance. Handles for the roll-up sidewallsFigure 9. End wall panels can be removed (left) and Greenhouse-grade Figure 11 shows the roll-up sidewall handlestored (right) during the summer. polyethylene films usu- design. The PVC pipe handle is easily moved to ally carry a manufacturer’s guaranteed life span roll the sidewalls up and down or lock the side- of three or four years under normal conditions. walls in place. Always roll up the sidewalls in a Covering the high tunnel should be direction that prevents water from accumulat- attempted only when there is little or no wind. ing in the roll. Before covering the high tunnel, rough edges on the structure should be taped or smoothed to prevent tearing of the plastic film. Unroll the plastic along one side of the structure and unfold it. For a 20-foot-wide high tunnel, you will need a piece of plastic at least 32 feet wide. Try not to let excessive moisture from rainfall or morning dew settle on the film before instal- lation. Tie a rope to one corner of the plastic and at 20-foot intervals down the sidewall edge. Figure 11. A 3⁄4-inch PVC t-handle (left) rolls the side- With the plastic wrapped around a tennis ball, wall vents up (open) or down (closed). a rope can be attached to pull it slowly over the frame. The plastic is easier to handle and pull over the bows when it is dry. Once the film is For further information pulled over the structure, make sure it is square Nagengast, D. 2003. Siting and building the by checking to see that all creases run in a hoophouse. In: The Hoophouse Handbook straight line. Attach the film to the frame in (L. Byczynski ed.) Fairplain Publications, four or five places to secure it temporarily while Lawrence, Kan. it is being permanently attached. Attach the University of Missouri Extension
  8. 8. 7 Producing Tomatoes in a High Tunnel Producing Tomatoes in a High Tunnel Many vegetable crops can be successfully Table 1. Plastic mulch effects on soil temperature.grown in a high tunnel. Tomatoes are particu- Mulch type Soil temperature increaselarly well adapted to production within a high (+) or decrease (–) (F)tunnel because tomatoes can be trained to grow Black +5vertically by trellising or staking. Early-season Clear +8–14tomatoes also reward growers with premium Infrared transmitting (IRT) +5–10prices because of the difficulty of consistently White -2harvesting field tomatoes before July in the Note: Soil temperature at the 2-inch depth.central Great Plains. Source: Penn State University Center for Plasticulture and University of Missouri.Production inputs A permanent high tunnel should be placed Organic mulches create a favorable environ-on fertile, unshaded, well-drained soils with a ment for many beneficial insects while increas-pH in the range of 6.0–7.0. Because high tun- ing organic matter. However, some organicnels are manually vented, they should be placed mulches (straw or hay) can significantly lowerin an accessible location. The soil should be soil temperature and thus would not be effec-tilled to a depth of 6–8 inches, and nutrients tive for warming the soil in the spring.should be applied based on a recent soil test. Compost (being dark colored) can increase soilTomatoes should be established on a raised bed. temperatures, but not as effectively as black Raised beds will significantly enhance plastic mulch. Organic mulches can be appliedtomato rooting by increasing soil warming, when soil temperatures have increased.drainage and volume. Tomatoes are a relativelydeep-rooted vegetable. An ideal raised bed is Irrigation Figure 12. Raised bedabout 8–10 inches high and 30–36 inches wide Because the high tunnel excludes natural with black plastic mulchat the top. Typically, a 20 x 96 high tunnel will rainfall, irrigation must be provided. Drip irri- (1-mil, embossed). Dripaccommodate five rows of tomatoes. Raised gation for tomatoes significantly improves mar- tape is placed under the plastic mulch.beds can be made with power tillers or compact ketable yield and overall quality. A uniformbed shapers attached to small tractors. After the application of water reduces fruit cracking andraised beds are formed, fertilizer, drip tape and other physiological problems such as blossomplastic mulch can be applied (Figure 12). end rot. The drip tape (a 3⁄4-inch small, collapsi- ble tube) should be buried slightly below theMulch soil surface 2–3 inches to the side of the plant For early tomato production, black, clear with the drippers on the top. Eight- or 10-milor IRT (infrared transmitting) mulch can be tape is acceptable with drippers spaced 4–12applied to increase soil temperatures and to inches apart. A drip system operates at 8–15 psireduce weed emergence and soil evaporation. pressure. (See the Appendix for a list of region-For maximum effectiveness, black plastic mulch al drip irrigation suppliers).should be in good contact with the surface of Tomatoes use a large volume of water, espe-the bed for effective transfer of heat. Embossed cially during fruit sizing. The fruit is about 95plastic mulch will fit tightly over the bed. Clear percent water. From fruit set to harvest, 1.5-3plastic will increase soil temperatures signifi- quarts of water per plant may be needed each day.cantly more than black plastic, but weeds will Soil moisture can be monitored with a ten-emerge under the clear film (Table 1). White siometer, a device that measures soil moistureplastic (white on black or white) will signifi- tension in centibars (cb). The drier the soil, thecantly lower soil temperatures and can be used higher the centibar reading from the tensiome-for high tunnel tomato production in late sum- ter. Place the tensiometer in the center of eachmer or fall. raised bed. When 50 percent of the available Organic mulches such as straw, hay or soil water is depleted, irrigation should occurcompost can be used for high tunnel tomatoes. (see Table 2).College of Agriculture, Food and Natural Resources
  9. 9. 8 High Tunnel Tomato Production GuideTable 2. Using a tensiometer to monitor soil moisture and irrigate tomatoes. preplant nitrogen is necessary. However, if your Soil texture Soil tension (cb) Soil moisture status soil organic matter is less than 3 percent, and Sand, loamy sand 5–10 you have not been supplementing the soil with Soil at field capacity. Irrigation is not organic residues, you should apply the equiva- Sandy loam, loam, silt loam 8 required. Clay loam, clay 20–40 lent of 1.4 pounds of actual nitrogen per 1,000 square feet (equivalent to 60 pounds per acre) at Sand, loamy sand 20–40 Irrigate tomatoes (50% of soil water or before transplanting (Table 3). Additional Sandy loam, loam, silt loam 40–60 is depleted). Provide approximately nitrogen can be applied by the drip system at a 2 quarts per plant. Clay loam, clay 50–100 weekly rate of 8–10 pounds per acre starting two weeks after transplanting. For example, An additional advantage of drip irrigation assume a 20 x 96 (1,920 ft2) high tunnel has in a high tunnel is the ability to inject water- five rows of tomatoes spaced 18" x 48". The soluble nutrients through the drip line as the total plant population in the high tunnel is 320 plant needs them. Generally, large quantities of plants. Providing 8–10 pounds of nitrogen per phosphorus and potassium should not be acre is equivalent to applying 19–24 ounces of applied through the drip system. Rather, based calcium nitrate (15.5N-0-0-19Ca) per 1,000 on a recent soil test, all the needed phosphorus square feet (Table 4). A 20 x 90 high tunnel and most of the potassium can be applied at containing 320 plants require 36–46 ounces of planting or between cropping cycles within a calcium nitrate per week. high tunnel. Additional potassium can be Taking tissue samples periodically through applied during harvest. About 40–50 percent of the growing season may be useful. Randomly the total nitrogen requirements for tomatoes select 10–12 plants per house. Break the fifth or can be applied before planting, and the balance sixth limb from the top of the plant and place can be applied through the drip system over the the entire limb in a brown paper bag. course of the growing season. Nitrogen Preferably dry the sample before sending to a requirements for tomatoes depend on the soil diagnostic lab for analysis. quality (i.e., organic matter) and previous crop- ping history. Generally, for each 1 percent Row covers organic matter content of your soil, you can Row covers are an important component of assume that there are 20 pounds of residual successful high tunnel tomato production. Row nitrogen per acre. Therefore, if you have covers are lightweight, spun-bonded organic matter levels greater than 3 percent, no polypropylene blankets that are supported loosely over the crop row or canopy. In theTable 3. Nitrogen rates for several granular commercial fertilizer analyses (pre- field, a light to medium-weight (0.5–0.9 oz/yd2)plant). row cover will increase air temperature around N required N per 1,000 ft2 10-10-10 13-13-13 20-20-20 the crop by 2–6 degrees F, while protecting the (lb per acre) (oz) (oz/1,000 ft2) (oz/1,000 ft2) (oz/1,000 ft2) crop from adverse weather and insect injury. 50 18 184 141 92 Using row covers in a high tunnel can signifi- 60 22 220 170 110 cantly increase the average daily temperature. 75 28 275 212 138 For early tomato production, row covers can be 100 37 367 283 184 two to three times more effective in a tunnel 125 46 459 353 230 than they are in the field. A medium-weight (single or double layer) row cover should beTable 4. Amount of several water-soluble fertilizers required to supply nitrogen(fertigation). placed over the plants after transplanting in March. Do not keep row covers on the toma- N required 15.5-0-0† 34-0-0‡ 20-20-20 (lb/acre) N/1,000 ft2 (oz) (oz/1,000 ft2) (oz/1,000 ft2) (oz/1,000 ft2) toes too long. During flowering, you will need 2 1 5 2 4 to remove the covers to ensure adequate polli- 4 1 10 4 7 nation. If temperatures become cold during 6 2 14 7 11 flowering, the row covers can be reapplied. In contrast to field conditions, wind cur- 8 3 19 9 15 rents do not remove trapped thermal energy 10 4 24 11 19 under the row cover within a high tunnel, andNotes: †Calcium nitrate ‡Ammonium nitrate the row cover acts as an insulating layer over University of Missouri Extension
  10. 10. 9 Producing Tomatoes in a High Tunnelthe plant. Another option is the use of plastic prolonged temperatures below 55 degrees orlow tunnels that act as mini-greenhouses (18- above 90 degrees, flowers can drop from the24" high) with a single or double layer of plas- plant. High humidity (higher than 80%) cantic (1-mil). Low tunnels can significantly also adversely affect pollination, producing cat-increase air temperatures but must be vented to faced (misshapen) fruit. The period betweenprevent excessively high temperatures. flowering and harvest is about 45 days for most Row covers can be kept on the plants from tomato cultivars.the time of transplanting (mid to late March) Because temperature and humidity affectuntil the appearance of the first flower cluster. tomato pollination, yield and fruit quality, theAt this point, they can be removed and kept in high tunnel environment should be monitoredreserve in the event of freezing temperatures. If carefully. In early spring, the period of ventingthe sidewall vents are rolled up (i.e., ambient is usually between 10 a.m. and 4 p.m. If lefttemperatures are warmer than 60 degrees) the unvented, a high tunnel can reach extremelyrow covers can be removed at any time. Row high temperatures (Figure 13). A 60-degree daycovers should be kept on tomato plants if the can produce 100-degree temperatures withinnight temperatures fall below 50 degrees. the high tunnel. The amount of venting required depends on prevailing winds and sun-Tomato plant characteristics light intensity. The goal should be to keep day- The tomato is a warm-season vegetable time temperatures between 75 and 85 degreescrop that is sensitive to frost and will be killed and relative humidity below 80 percent. If thereby freezing temperatures. Tomato plants have is a forecast of frost, close the vents in midafter-either a determinate or an indeterminate noon and place row covers on the plants.growth habit. Determinate tomato vines pro-duce side shoots that terminate in a flower clus- High tunnel tomato cultureter, and the plant reaches a height of 3–4 feet.Therefore, yield is concentrated over a 4- to 6- Producing transplantsweek period. Indeterminate tomato plants con- In a high tunnel, tomatoes are usually estab-tinue to produce additional vines and flower lished by transplants. The critical first step inclusters throughout the growing season and transplant production is to purchase quality seedmay reach 5–7 feet in height. of a cultivar that possesses characteristics you Tomato plants do not need a specific day prefer. One ounce of tomato seed contains Note:length to flower. The flowers are self-pollinat- 6,000–12,000 seeds. (See the Appendix for a list 1 oz/gallon = 75 ppmed, but physical vibration of the flower by shak- of tomato seed suppliers.) The optimum germi-ing the plant, wind movement, or insect polli- nation temperature for tomato seed is 75 To determine the parts per million (ppm) of anation will promote pollination. The optimum degrees F, and the optimum temperature range specific fertilizer nutri-temperatures for pollination are 68–75 degrees for growth of the transplant is 60–70 degrees. ent, multiply the per-F at night and 60–90 degrees during the day. At Seeds should be sown in a germination flat or centage of the nutrient 50- to 72-cell tray 5-7 weeks before you antici- by 75. The product will be ppm of the nutrient Open pate transplanting. Container size is important per ounce of the fertil- Close 120 vent vent for early tomato production. Research has izer dissolved in 100 100 90 revealed that the container for a tomato seedling gallons of water. 80 should be at least 2.25 inches in diameter. For For example, if you 70 wish to prepare a 200 example, if the seed is sown in a 72-cell tray, the Temp (ºF) 60 ppm nitrogen solution 50 seedlings can be replanted in a 606 Compack 40 of 20-20-20, 30 (2.25" x 2" cell) flat beginning at the two-true- 0.20(75) = 15. Thus, 20 leaf stage. Low light or excessive watering, in 1 ounce of 20-20-20 10 0 nitrogen or temperature will cause excessive (dissolved in 100 gal- 12 . . . . am “leggy” growth. Transplants should be fertilized am . pm pm . . . 10 . . . . am pm lons of water), there am pm am pm am pm 12 10 2 2 6 6 8 8 4 4 Time with 100–200 ppm of nitrogen per watering. are 15 ppm of nitrogen. To make a 200 ppm Outside High tunnel For example, approximately 1 pound of 20-20- solution, (200 ppm 20 can be dissolved in 100 gallons of water for a 15 ppm/oz) 13.3Figure 13. Daily temperature fluctuations in anunvented (single plastic layer) high tunnel, Columbia, fertilizer source. A good tomato transplant ounces of 20-20-20 willMo. (3/27/02). should be stocky. Tomato transplants can be be needed.College of Agriculture, Food and Natural Resources
  11. 11. 10 High Tunnel Tomato Production Guide conditioned or “hardened off” before trans- First flower planting. Hardening of tomato plants enables cluster the plants to survive the shock of transplanting within the high tunnel in early spring. Plants that are not properly hardened will be slow to Leave this sucker start growth after transplanting. Hardening of (below first flower cluster). tomato transplants can be accomplished by tak- Do not prune ing plants from the greenhouse about 10 days higher on Remove all other the plant before transplanting and exposing them to out- suckers below side temperatures (no cooler than 55 degrees) and wind for a few hours each day. Transplanting Tomato plants can be transplanted when soil temperatures reach 60 degrees F at a depth of 2 inches. A starter solution of fertilizer (e.g., Figure 16. Remove all but one sucker below the first 9-45-15) should be used to promote root devel- flower cluster to achieve balance between vine and opment. Three pounds of the dry material is fruit growth. mixed per 50 gallons of water and one-half pint tunnel, one of the preferred ways to train toma- is applied to each plant. For early tomato pro- toes for early harvest is the stake-and-weave duction, row covers, raised beds, drip irrigation system. Drive a 48–52" x 1" square wooden and plastic mulch are essential. You may wish to stake (or metal rebar) that is driven between invest in portable backup heaters if you feel the every other tomato plant (Figure 14). When the risk of a freeze is great. tomato plants reach a height of 12 inches, the A tomato plant in a high tunnel should first string can be applied. Nylon plastic twine occupy 4–6 square feet of land. Early-yielding is the best source of string. Every 6 inches of new growth will require a new string to provide support for the tomato vine and fruit load. Caging tomatoes is another option for training. If you choose to trellis tomatoes from the roof frame, make certain your high tunnel frame can support the crop load. Otherwise, tensile wire supported by metal posts can be used to trellis the vines. String tool Pruning, the removal of suckers or axillary shoots that grow between the leaf and the main stem, will accelerate early harvest and improve disease tolerance by enhancing air circulation around the plant (Figure 15). While pruning may be too labor intensive for field production, tomatoes in a high tunnel should be pruned ifFigure 14. Staking and stringing of tomato plants will improve fruit quality and the objective is early harvest. Pruning will notearly marketable yield. increase total marketable yield. The purpose of cultivars that do not produce a large vine can be pruning is to achieve a balance between vine spaced closer than midseason cultivars or those and fruit growth. Remove all suckers up to the that tend to have vigorous vines. one below the first flower cluster, resulting in two stems per plant (Figure 16). Prune when Training and pruning the suckers are less than 4 inches long, and do Training tomatoes within a high tunnel is not prune the plants if they are wet. After prun- very important. When tomato are staked, light ing, you may wish to apply a labeled fungicideFigure 15. Pruning interception and disease tolerance are improved to protect against disease outbreak.(suckering) tomatoplants accelerates early and the plant is more likely to set early fruit, See Table 5 for a guide to troubleshootingharvest. and disease tolerance is improved. For a high problems with tomatoes in high tunnels. University of Missouri Extension
  12. 12. 11 Producing Tomatoes in a High TunnelTable 5. Troubleshooting tomato problems in a high tunnel. Problem Possible cause Solution Temperatures are either too cool or too warm. Proper venting for temperature management Flowers falling off plants Thrips See Midwest Vegetable Production Guide for Commercial Growers Flowers fuse together Too cool. Proper temperature management Fruit catfaced or misshapen Pollination disorder. Humidity may be too high or temperature too low. If the upper leaves experience cupping or rolling, check for aphids. Aphids produce sticky Aphids can be controlled by using registered, labeled organic or excrement that attracts flies and ants and is synthetic pesticides and releasing beneficial insects. colonized by a dark fungus. Cupping or rolling of leaves Some early-season cultivars roll or cup their Genetics leaves when they have a heavy fruit load. Water stress (excess or deficiency) Irrigation management Temperatures are too high or low, or humidity Temperature management. Do not keep row covers on plants too is excessive. long. Poor fruit set Flowers are not being vibrated enough for Roll up sidewalls if temperature permits. Shake tomato stakes to pollination. promote pollen release. Use bumblebees. Disease that is promoted by high humidity and cool, cloudy Fruit has gray mold on the Gray mold (Botrytis) fungus weather. Vent high tunnel properly. Use labeled fungicides, and stem end increase air circulation around the fruit. Bt insecticides should be applied every 8–14 days beginning at Border rows have fruit with Worm feeding flowering. If worms are visible, you may wish to use another holes. Foliage feeding. labeled pesticide. Stem lesions cause the Disease Have plants diagnosed by your local extension specialist. plant to wilt. If picking during hot weather, use a shade cloth. Late fall tomatoes Fruit fails to ripen Temperature may not ripen because of low light and temperatures. Blossom end rot is caused by a localized deficiency of calcium to the developing fruit. Make sure your soil has medium to high Black spots on bottom of calcium levels; water uniformly; do not overapply NH4 fertilizers or Blossom end rot fruit overprune. Calcium can be applied through the drip system. Do not apply foliar calcium. Fruit cracking Irregular watering Mulch and water uniformly.Table 6. Some tomato varieties for high tunnel production. Days to Disease Variety Comments harvest resistance Determinate BHN 543 72 F12 V1 Midseason early; Excellent size, shape and quality. Carolina Gold 75 F12 V1 GW Yellow (tangerine) colored fruit; Vigorous vine. Excellent quality. Florida 47 75 F12 V1 Large, smooth, crack-resistant fruit; Good quality; Vine slightly less vigorous than Fl 91. Florida 91 72 F12 V1 Large, smooth, crack-resistant fruit. Heat-set variety with good disease tolerance. Floralina 72 F123 V1 Large, smooth, crack-resistant fruit. Very good taste. Merced 69 F12 V1 Early; Good quality. Has a tendency to crack in the field but not the high tunnel. Mountain Fresh 78 F12 V1 Excellent midseason variety; Very good quality. Vigorous vine. Good disease tolerance. Mountain Spring 70 F12 V1 Early; Excellent fruit size. Sunleaper 70 F12 V1 Heat-set variety good for summer and fall production. Indeterminate Trust F12 V1 Excellent quality and yield Big Beef 73 F12 V1 Excellent yield 1Thislist is not intended to include every variety that may perform well in a high tunnel. F = Fusarium wilt race 1, 2, 3 V = Verticillium wilt GW = Gray wallCollege of Agriculture, Food and Natural Resources
  13. 13. 12 High Tunnel Tomato Production Guide Figure 17. Tomatoes can be packed in single- (15 lb) or multiple-layer (20–25 lb) boxes for market. Variety selection or shipping containers for tomatoes vary. Typically tomatoes are packed in 20- to 25- The essential first step in successful high- pound boxes or single layer, 15-pound boxes tunnel tomato production is selection of a suit- (Figure 17). able variety. Table 6 lists several varieties that Do not refrigerate vine-ripe tomatoes or have performed well in high tunnel trials at the allow the fruit to be exposed to temperatures University of Missouri. higher than 85 degrees. If tomatoes are held in storage, the temperatukre should be 50–75 Harvest and postharvest handling degrees F with 85–90 percent relative humidi- Tomatoes can be harvested for vine-ripe ty. On hot days, pulp temperature of tomatoes fruit about 45 days after flowering. However, can be 20 degrees warmer than air tempera- tomatoes continue to ripen when picked at any tures. Picking fruit early in the morning or in stage from mature green onward. If high tunnel the evening reduces field heat. Shade cloth can tomato production is extended into late fall, significantly lower temperatures in the high mature green fruit can be harvested before a tunnel during harvest in late June and July. hard freeze and allowed to ripen at room tem- Tomatoes can be packed immediately after har- perature. Mature green fruit can also be har- vest without washing, or growers can clean the vested and allowed to ripen at room tempera- fruit with chlorinated water. If the fruit is ture. Mature green fruit exhibits a color break washed, do not use ice or cold water, and the in the shape of a star at the blossom end. water should be properly chlorinated for sani- Another way to gauge maturity is to cut the tation (125 ppm). The pH of the wash water fruit, and if the seeds are cut, the tomato is not should be 6.5–7.0. A washing and sizing unit ready to harvest. can be used to clean and size harvested fruit. Tomatoes are graded as USDA No. 1, No. Avoid storing vine-ripe tomatoes with fruits 2, and No. 3. Within each grade class, tomatoes such as apples or cantaloupes. These fruits can be sized as jumbo (more than 3.5" diame- emit ethylene, a gas hormone that accelerates ter); extra large (2.75" to 3.5"); large (2.5" to ripening of tomatoes and can reduce their shelf 2.75") and medium/small (less than 2.5"). Boxes life. Also from Extension Publications 1-800-292-0969 MU publication MX 384, Midwest Vegetable Production Guide for Commercial Growers, 177 pp. This comprehensive guide, revised annually, gives a wealth of information on how to protect your vegetable crops from insect and disease pests. It contains reference sections for planting, spraying, cultivating, harvesting and storing more than 30 vegetables common to the Midwest. In addition, dozens of tables give information on varieties, maturity dates, handling and storage life, estimated yields per acre and more for each vegetable. University of Missouri Extension
  14. 14. 13 High Tunnel Temperature Management High Tunnel Temperature Management Temperature management is one of the Extremely high temperatures (above 90most critical components of successful high degrees) can cause tomato flowers of some cul-tunnel tomato production. Early-season toma- tivars to abscise and will prevent the tomatotoes can be successfully grown in the central from developing a uniform red color. HighMidwest without supplemental heat. Using temperatures cause the tomato leaves to turnraised beds, plastic mulch and row covers in the brown at the margins; the plant looks almost ashigh tunnel will significantly increase average if it has been in a furnace. Using shade fabricdaily temperatures. Adding a second layer of (30–50%) from late June through July harvestpolyethylene covering will reduce heat loss and will significantly lowerthe formation of condensate on the inside sur- temperatures within theface of the cover. Growers who wish to use high tunnel.heaters may find them useful in protecting the Shade cloth can becrop during a hard freeze and in accelerating applied externally overgrowth of the tomatoes. the high tunnel in June The optimum temperature for growth of and removed in early fallthe tomato plant is 70–75 degrees F. Average (Figure 18). The shadedaily temperatures should not be lower than 65 cloth should not coverdegrees. Temperatures below 55 degrees dur- the sidewall vents. Toing flowering can reduce fruit set and produce calculate the width ofmisshapen fruit. Growers must monitor tem- shade cloth needed, use Figure 18. Shade cloth applied over the high tunnel moderates midsummer temperatures.peratures carefully by placing a minimum/max- the following formulaimum thermometer in the center of each high for a semicircular (arched) structure:tunnel at the height of the tomato canopy. ((W/2) x 3.14) – (Hsw x 2),Shade the thermometer to avoid false highreadings due to direct exposure to sunlight. where W = width of the high tunnel and Hsw = For early-tomato production, April is the height of the sidewalls.most variable month for temperature within the Figures 19–25 show daily temperaturehigh tunnel. Often, the vents are adjusted three cycles throughout the 2003 growing season asor more times per day to maintain an optimum recorded in the University of Missouri hightemperature. Roof vents or vents at the top of tunnel trials.the end walls may be useful in preventing exces-sive heat and humidity buildup within the high 100 90tunnel. 80 70 120 60 50 Temp (ºF) 100 40 80 30Temp (ºF) 20 60 10 40 0 1 5 9 13 17 21 20 Time (hours) 0 Outside High tunnel 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 Time (hours) Figure 20. March 15, 2003. Tomatoes were trans- Outside Inside Inside planted. Ambient conditions were sunny and warm. (no rowcover) (rowcover) All vents were closed. The average 24-hour tempera- ture in the high tunnel was 56 degrees F relative toFigure 19. January 16-20, 2003. Row covers (double 51 degrees F ambient temperature. The growinglayer; lightweight) were used to overwinter lettuce degree day (gdd) base temperature for tomatoeswith excellent results. below which growth is negligible is 51 degrees F.College of Agriculture, Food and Natural Resources
  15. 15. 14 High Tunnel Tomato Production Guide 80 90 70 80 Vents closed 60 70 60 50 50 40 Temp (ºF) Temp (ºF) 40 30 30 20 20 10 10 0 0 1 5 9 13 17 21 1 5 9 13 17 21 Time (hours) Time (hours) Outside High tunnel Outside High tunnel Figure 21. March 30, 2003. Ambient conditions: Cool, Figure 22. April 4, 2003. Warm morning, then turning sunny with vents closed. Twenty-four hour tempera- colder through the day. Winds WNW; vents opened ture average within the high tunnel was 48 degrees F on east side and closed at 3 p.m. compared with 36 degrees F ambient conditions. 120 90 80 100 70 80 60 50 60 Temp (ºF) Temp (ºF) 40 40 30 20 20 10 0 0 1 5 9 13 17 21 1 5 9 13 17 21 Time (hours) Time (hours) Outside High tunnel High tunnel Outside High tunnel & row cover Figure 23. April 21, 2003. Flowering of tomatoes Figure 24. May 31, 2003. Ambient conditions: Cloudy, observed. Ambient conditions: Cloudy, cool morning; cool. Vents open until 6 p.m. Sunny afternoon. Vents closed. Single layer of light- weight row cover used. 100 90 80 70 60 50 Temp (ºF) 40 30 20 10 0 1 5 9 13 17 21 Time (hours) Outside High tunnel High tunnel/ shade cloth Figure 25. July 4, 2003. Tomato harvest. Shade cloth (47% black) significantly lowered temperatures and improved ripening of high tunnel tomatoes. University of Missouri Extension
  16. 16. 15 Cropping Systems for Tomatoes in High Tunnels Cropping Systems for Tomatoes in High Tunnels Seed tomatoes Seed lettuce Relay tomatoes Transplant for transplants Seed carrots Seed lettuce into lettuce and basil Relay lettuce Seed beets, for transplant into tomatoes carrots, spinach, transplants brocoli, kale & Relay 2nd tomato into tomatoes crop (grape) lettuce carrots under row covers into basil Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Harvest Harvest Harvest basil Harvest Harvest lettuce Harvest lettuce grape lettuce & carrots tomatoes tomatoes Remove basil Intercropping system plantsFigure 26. A hypothetical intercropping system for tomatoes in a high tunnel in central Missouri. Intercropping is the growing of two or be relay planted into the existing lettuce bedmore crops within the same production area (Figure 28). Because the root systems of lettuceduring part of the life cycle of each crop. and tomatoes do not compete, fertilization prac-Intercropping in a high tunnel allows growers tices for the tomato can be used for both cropsto produce many vegetables within a limited without diminishing the yield of either. Lettucespace and thus improve the output of the high harvest begins in April and extends throughtunnel. Interplanting one vegetable with anoth- mid-June. Peak yields of lettuce occur beforeer after the first vegetable has become estab- tomatoes set fruit. Tomato harvest begins inlished is called relay intercropping (Figure 26). mid-June and extends through July. The lettuce does not accumulate nitrates. Both crops areCropping system I able to maximize yields without competing withTomatoes interplanted with lettuce each other. Starting in January, leaf lettuce can be directseeded onto preformed raised beds within thehigh tunnel (Figure 27). Each raised bed is24–30 inches wide by 6–10 inches high. The let-tuce is direct seeded as two or three rows perbed, 6–8 inches apart. In March, tomatoes can Figure 28. Lettuce, carrots and basil are among the crops that can be intercropped Tomato successfully with tomatoes in a high tunnel. plants Cropping system II Tomatoes interplanted with carrots Carrot & lettuce Carrots can be seeded as soon as soil tem- understory peratures reach 45 degrees F. For example, car- rots can be seeded from February through early April in a high tunnel. Tomatoes can be relay 6-8 in. 6-8 in. interplanted into the carrot bed with no loss in 6-10 in. yield of either crop. The carrots can be harvest- ed one month to one week before harvest of the 24-30 inch width tomatoes begins.Figure 27. Cool-season crops can be interplanted withtomatoes in preformed raised beds.College of Agriculture, Food and Natural Resources