The growing Demand for Essential Oils for Agricultural Applications
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The growing Demand for Essential Oils for Agricultural Applications

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The growing demand for essential oils for agricultural Applications

The growing demand for essential oils for agricultural Applications

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  • Hi Murray, I simply cannot get enough of your work. Great stuff! Have you ever come across Lippia javanica as fungicie and insecticide for mangos, avocados and citrus?
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The growing Demand for Essential Oils for Agricultural Applications The growing Demand for Essential Oils for Agricultural Applications Document Transcript

  • The Growing Demand for Natural Products in Agricultural Applications Mohamed Murray Hunter School of Bioprocess Engineering Northern Malaysian University College of EngineeringIntroductionEssential oils are a source material for the manufacture of fragrances, flavours andpharmaceuticals and is a centuries old industry. The flavour and fragrance industry oncecompletely relied on natural materials until the 1930’s, when synthetic materials began to gainacceptance. The development of synthetic materials acted as a catalyst in changing thenature of the cosmetic and food industries, allowing much wider fragrance and flavour use inend-products. This was due to lower cost of synthetic materials, the increased stability overwider pH ranges they offered, better resistance to oxidisation, and the elimination of dis-colourations in products, which had plagued natural fragrances1. This changed cosmeticsfrom being a product for only the wealthy, to being a product that all could afford. However,this also dampened growth drastically for natural products, as society became fascinated withthe ‘brave new’ synthetic world of chemistry. Likewise, before the 1980’s, natural plantextracts were only a novelty until manufacturers of cosmetics, personal care and householdproducts realised the marketing potential of these materials for ‘green’ product positioning.Lifestyle changes in the West, enhanced through rising incomes and standards of livingpropelled many natural and tactile therapies into peoples’ lifestyles, thus bringing resurgencein demand for essential oils and other plant extracts again.The 1980’s and 90’s saw the golden age of pytho-entrepreneurship, where essential oil, herband plant extract production boomed and almost went unchecked by the regulatoryauthorities. People began growing ginseng in their garages, selling them in the open marketand growing all sorts of new exotic herbs and essential oils until marketing claims becametotally outrageous. The EU introduced heavy regulation, the US FDA became much stricterand most countries in South-East Asia developed their own version of the FDA or enactedlegislation controlling this industry. Now the essential oil, herb and plant extract trade is fallingback into the hands of the larger international manufacturers and traders, who have theresources to deal with regulatory authorities, eliminating the opportunities existed duringthose two decades.Other than natural market growth, around 3-5% per year, there is no real growth for essentialoils and plant extracts in their traditional markets, and certainly very little opportunity for anynew essential oil or plant extract to be developed internationally, on a large scale.However, the same cannot be said for the use of essential oils and plant extracts in theagricultural market. Agriculture itself is currently undergoing a revolution with major changesin practices taking place. Agriculture is being redefined. Those involved in agriculture onceheld the view that the environment can be totally controlled through fertilisers, pesticides,herbicides, hormones and trace elements. However accepted practices began to show theirshortcomings and basic assumptions about agriculture re-questioned. Evidence showedconventional practices led to phosphates, heavy metals and herbicides seeping into watertables, crops absorbing unsafe levels of chemicals and land just failing to provide satisfactoryyields, due to unsustainable practices. In some cases, agricultural communities have justbeen wiped out and ceased to exist or continued to operate with negative capital returns.As a result, Agriculture has gone back to the future, farmers re-evaluating the ways, practicesand methods of the past. New paradigms have been developed with the catch phrases of‘sustainable’, ‘integrated’, ‘organic’ and ‘balanced eco-system’. The ‘new-age’ farmer is muchmore sensitive to the eco-system that supports the viability of the enterprise and as aconsequence is beginning to use a much wider information base to make decisions, with aholistic orientation, understanding in great detail relationships between ‘inputs’ and ‘outputs’,focusing on balance.
  • Agriculture was once a so precise science that farmers believed they knew what remedy touse for what problem and even knew how to prevent these problems through establishingprecise and disciplined preventative regimes and methods. Modern science provided thissense of confidence with hi-tech solutions such as using geo-stationary satellites to predictcrop yields and insect plagues and through land sensing, could advise what fertiliser, howmuch, and when to apply it, to obtain the planned yield. A massive agro-chemical businessevolved, providing all the technical answers needed, dominated by strong trans-nationalcompanies, where almost total oligopoly competition exists.The New Age of AgricultureThree main factors are forcing change in agriculture.Firstly, consumers have become much more aware of what they are eating and want foodthat is free of toxic chemicals, heavy metals, hormones and the like. These issues are beingscrutinised so closely these days that consumer groups have put up such a fight against theintroduction of genetically modified (GM) crops out of fear that changed DNA, may have someunknown and undesirable long term health effects on consumers2. In sensitivity to theconsumer, some companies are even labelling food as non-GM. This awareness is spurringthe rapid growth of organic foods, where “organic farming is practiced in approximately 100countries throughout the world, with more than 24 million hectares (59 million acres) nowunder organic management. Australia leads with approximately 10 million hectares (24.6million acres), followed by Argentina, with approximately 3 million hectares (7.4 million acres).Latin America has approximately 5.8 million hectares (14.3 million acres) under organicmanagement, Europe has more than 5.5 million hectares (13.5 million acres), and NorthAmerica has nearly 1.5 million hectares (3.7 million acres)”3. Further, organic farming hasshown an increase of 20% per annum over the last decade and now approximately 2% of the 4U.S. food supply is grown using organic methods . The global market for organic food and 5drink reached $23 billion in 2002 .Secondly, conventional agriculture in Malaysia has caused eco-system contamination,particularly in the water tables and ponds located in agricultural areas. Land also containstraces from build up of residual chemicals used in agriculture.Thirdly, to maintain sustainability of farms, the strategy of applying more chemicals in the formof pesticides and fertilisers was pursued. Land is not being rotated and topsoils are beingeroded, thus requiring more nutrient replenishment, which continues to increase the cost toachieve the same yields, each year, in a vicious circle.The first factor indicates a distinct shift in consumers tastes and habits, which is leading tochanges in demand – this is a long term shift. To be viable and survive, a farmer must supplyaccording to demand, or the enterprise will soon go out of business. This is the invisible handthat determines what should be produced, consumer trends must be heeded by farmers orthe farm enterprise will be marginalised. The second and third factors combined are erodingprofitability, making farming more marginal and unsustainable in the long term. This factor isthreatening survival from the supply side. These factors combined, the market in an economicsense, is forcing a change in the approach taken to farming, as its very survival will dependon it – it is a structural change. Those that read the market correctly will survive and prosper,those that don’t will not survive. The little bit of evidence that supports this argument is thedramatic growth of certified organic farms in Malaysia between 2001 and 20026.This changing approach to agriculture is redefining the framework that farmers now view fieldmanagement. The old and new paradigms are summarised and compared in table 1 below7;
  • Comparison of the Industrial andBiological Models of Agriculture Industrial Model Biological ModelEnergy Intensive Information IntensiveLinear Process Cyclical ProcessesFarm as a Factory Farm as an EcosystemEnterprise Separation Enterprise IntegrationSingle Enterprise Many EnterprisesMonoculture Diversity of Plants and AnimalsLow-Value Products Higher Value ProductsSingle Use Equipment Multiple Use EquipmentPassive Marketing Active MarketingThese approaches require a completely new approach, in regards to the types of chemicalsused. Agricultural chemicals must now support the eco-system (i.e., prevent furthercontamination and pollution of the water tables), add value, promote sustainability and assistin providing long term profitability.The New Tools of TradeOnly certain types of fertilisers and pesticides are allowed in organic farming, including thosederived from micro-organisms and materials derived from plants, animals, or mineral bearingrocks. Soaps are also allowed under many certifying authorities. Generally, pesticides andsoaps allowed for organic farming are those that will break down quickly and non obtrusive tothe eco-system. The discussion will now turn to some of the types of materials used inorganic and sustainable farming. 1. Enzyme catalysts and Fertiliser/InsecticidesThe use of enzymes as catalysts to produce composts and organic fertilisers is widelypracticed in Australia, Europe, US, India and Thailand. By definition, this is a practical 8application of bio-process engineering . In Thailand, where organic agriculture is quicklyadvancing, many farmers have been taught the skills and acquired the knowledge to producetheir own enzymes for use as a catalyst to produce fertilisers through the fermentationprocess. By adding certain other ingredients into this process like the leaves and fruits ofneem, citronella grass and tobacco leaves, fertiliser/insecticides can be made. Other productslike Pseudo Hormones are also made using variations of the basic enzyme formula topromote flowering and the production of fruit.Local production of these enzymes developed because the importation of bokashi(photosynthetic organisms, lactobacillus) was too expensive to purchase. Consequently, theproduction of enzymes developed through trial and error and experience, rather thanscientifically. Farmers develop their own fermentation formulae, which suits their particularpurposes, specific to their geographical locations, crops and raw materials available. This ofcourse means that the relative activity of different products will vary greatly depending on theskill and knowledge of individual farmers.The basic ingredients in the production of the ‘EM’9 include fruits, vegetables and animalwaste. Fruits are rich in natural enzymes, which act as a catalyst to ripen and thendisintegrate the same. Different fruits will produce different enzymes (i.e., citrus fruits ascorbicacid oxidase, pineapple bromelase, tomatoes pectinase, and papaya papain). Vegetablesproduce other enzymes, which like the fruits catalyse cellulose in the leaves to crispness andlater softness and disintegration (i.e., sweet potatoes beta-amylase, leafy vegetableschlorophyllase and phenolase). Animal waste will produce yet other enzymes (i.e.,peroxidase, elastase, lactase, etc).The primary enzymes that are produced at farm level are proteases in the form of bromelasefrom pineapples (Ananas comosus) and papain from papaya (Carica papaya). Bromelain isreally a collection of similar protease, which are good protein digesting enzymes. Papain is
  • also good at breaking down fibrous substances. These are important qualities in producingcomposts and fertilisers. The table below shows a general formula for enzymes produced atvillage level. As mentioned previously, most people will have their own proprietary methodsand ingredients.A General Enzyme Base for Fertiliser productionBanana, grape, Pineapple, apple, orange, 6 kilograms in various proportionspapaya, Mango stein according to person’s own formulaMolasses 3 kilogramsWater 20 kilogramsChicken or cow manure 3 kilogramsProcedure: Place all ingredients together in asealed tank and mix. Leave for at least oneweek. This process can be sped up byplacing an existing enzyme in the mixture.Once this base enzyme is ready, it can be used in the preparation of solid or liquid typefertilisers. Through varying the inputs into the fermentation process, it is possible to producespecific groups of enzymic compounds, which can be tailored towards specific applications,such as specific crops and soil types, while other products can be made by the household likecosmetics and detergents. Some farmers are producing their own herbicides for controllingweeds10.Common Enzymes, Potential Sources and Other Potential ApplicationsEnzyme Potential Sources Potential ApplicationsAscorbic acid Citrus fruits, leaf vegetables, Fruit preservation, cleaningoxidase cucumbers applicationsBeta-amylase Grains, sweet potatoes, taro, Yeast production cassavaBromelains Pineapples Fertilisers, pseudo hormones, cleaning, cosmetics, personal care, mouthwashes, skin healing, anti- acne, anti-microbialCatalase Animal wastes, milk wastes Cosmetic, anti-ageing, oxidisingChlorophyllase Some leaf vegetables UV absorptionElastase Animal intestines Cosmetics, anti-agingGlucoxidase Some mushrooms, mould, other Anti-oxidant fungiPapain Papaya Fertilisers, wound and skin healing, mouthwashes, other cosmetics, dishwashing, all purpose cleaning
  • Preparation of the enzyme base in SabahThe use of the enzyme in preparing solid fertiliser 2. Essential Oil Based Fungicides/Insecticides A new generation of crop protection products is emerging in the market, based on a soap and essential oil emulsion. These products take advantage of the anti-microbial properties of tea tree oil (Melaleuca alternifolia) to function as a fungicide. Biomor of the United States manufactures these products under the trademarks of Timor and 11 Tomorex . These products are certified as fully organic and are sold as fungicides and insecticides. The company claims that these products can be tailor made to selectively attack insects, leaving those beneficial alone. It is further claimed that these products leave no residual and can fully negate the need to use copper or sulphur in field
  • application. The following photo shows the efficacy of the product on cucumber leaves, 12 compared to a control and commercially available synthetic . Nimgard + Kocide Control Timorex 0.5 % Timorex 1 %The company solved the problem of essential oil volatility through patented encapsulationprocesses13, and sales have rapidly grown to a turnover of USD 50 million per annum, withinthe first three years of operation14, through South America, South Africa, Philippines, Greece,Australia and the United States. According to the company sales growth is severelyhampered by the unavailability of enough tea tree oil to expand production. 3. Natural Anti-Stress Preparations from Betaines and Essential Oils Degrading soil fertility, salinity, heavy metal residuals in the soil, and the effects of global warming, are subjecting crops in many temperate countries to stress. This has created a market for anti-stress products, which is slowly growing in importance to agriculture. The essential oil of some trees, Meleleuca bractea for example, have been found to substantially reduce the stress of crops15. Plant stress levels can be lowered by applying betaines produced from methylated prolines, N-methyl proline, trans-4-hydroxy-N-methyl proline and trans-4-hydroxy-N-dimethyl proline, extracted from various specifies of Meleleuca16. A compound platyphyllol17, found in Melaleuca cajuputi, a native of Malaysia, has ‘UV blocking’ attributes18, This could be used in treatment of plant stress, as one of the major stressors of plants is UV radiation. None of these natural products have been patented for this application or commercially produced at this point of time.
  • Melaleuca cajuputi trees in Terengganu4. Plant Extracts: Neem based ProductsNeem (Azadirachta indica A. Juss) is considered be many to be one of the wonder treesin our global bio-diversity. Numerous uses for this tree have been both reported andpracticed by many indigenous peoples over the centuries. Neem is a major input in Thaiand Indian agriculture for the production of natural insecticides at farm level. Neemcontains a number of compounds of which two ‘steroid like’ molecules, azadirachtin and 19salanin , exhibit very potent insect repellency attributes. Neem does not knock downinsects like conventional pesticides, but rather interferes with the lifecycles, confusingthem to the point they cannot reproduce and thus disappear20.The potential for neem as an agricultural input is tremendous, however there are anumber of problems. Plantations of neem in Malaysia are very small, and even if therewere massive plantings today, they trees could not be used for 5 years. ‘Neem oil’, whichis not a true oil in the real sense but a tincture, can be extracted through solvents orthrough soaking out the active ingredients in a bin or tank in water. The ‘oil’ or tinctureresulting, is very unstable and will lose activity within a relatively short period of time.Standardisation problems have been found with neem oil is available from India, whichmakes it difficult to use in large commercial operations practicing standard processes.Finally, there is an unresolved health and safety issue as neem also has contraceptiveattributes, preventing neem from gaining registration as an agricultural material in manycountries. Even though, this issue could be addressed, there is no central neem industrycoordination group to raise finance to undertake the required research to produce amonograph.
  • Neem Tree in Perlis 5. Plant Extracts: Pyrethrums Pyrethrum based products are rapidly growing in demand for application as a pesticide in agriculture. Under most jurisdictions it is organically certifiable. Pyrethrum is extracted via solvents (usually hexane) from the flowers of Chrysanthemum cinerariifolium, which could grow well in many highland areas of Malaysia. Natural pyrethrum used to be the major active ingredient in household insecticides before the synthetic pyrethroids, which have much longer residual effects were developed. Natural Pyrethrums are non-toxic to humans and is known as one of the safest pesticides in use. The advantages of natural pyrethrum is that it has a fast knock down effect on insects, through attacking the insect nervous system, however the substance is very unstable in UV light, which breaks it down very quickly. Pyrethrum is usually applied as a spray on crops during the growth and maintenance periods. Pyrethrum Daisy
  • 5. Essential Oils in Soap Bases Citronella oil soaps became popular in the 1980’s as a way to control insects on flowers and vegetables. This type of product was popular by a select group of nurseries and horticulturalists at the time because of the non-residual properties and low toxicity of these products. The efficacy of the product depended on suffocating insects during spraying and causing enough irritation for them to abandon the host plants. Soaps with essential oil additives are quite effective in intensive and confined areas, but of limited use in extensive farming due to the number of repeated applications required to maintain zero pest infestation. Variations of this product utilising eucalyptus, rosemary, pennyroyal, clove, nutmeg and tea tree oil have come onto the market in recent years. This type of formulation could be considered the forefather of the newer organic fungicides, mentioned under the first heading. The author patented this formulation in 1986, which is marketed under the brand Clensel in Australia, New Zealand and UK21, under license with Jeyes UK Ltd. Clensel Insecticide Formulation Water 86.09% w/w Potassium hydroxide 2.02%w/w EDTA 0.0879%w/w Oleic acid 10.60%w/w Citronella oil 1.099%w/w Sodium carbonate 0.8798%w/wClensel Insecticide Label7. White Oils White oil is a name given to oils emulsified in a soap base. Any number of oils including, paraffin, mineral oil, canola, caster, sunflower, can be used. These products are generally used to remove various funguses and scales from plants and trees. Some people add either ammonia or vinegar to the formulation to enhance the efficacy and add some insect repellency and enhance crop greenness before harvest. In general use these emulsions
  • are sprayed over the plants. For diseased plants, they are manually applied and rubbedaround the infected areas of the tree to remove the fungus and scales. There are manyvariations of this product on the market, with different philosophies and approaches.Traditional oils like paraffin22 are used by many, however with the long CH2 chains, 30 inthis case, brings phototoxicity issues which can be potentially fatal to the plant. In additionthese long chain oils may carry sulphur residuals. Also the film created by these oils canblock the stomata (intake apparatus of the plant), preventing nutrients being taken up.Some practitioners opt for the vegetable oils and create mild soaps with various additivesto assist in killing fungus spores and removing scales, like eucalyptus or tea tree oils.A simple mild white oil formula with eucalyptus oil as an additive and preservative isshown in the table below; A Simple White Oil Formula Water 58.0%w/w Castor Oil 30.67%w/w Potassium hydroxide 5.78%w/w Eucalyptus Oil 5.55%w/w8. Organic DustsGarden dust is a multi-purpose insecticide/fungicide made up with a bulking agent andvarious synthetic and/or natural plant derivatives. Garden dust is used against plantdiseases like powdery mildews, bacterial blights, early blights, fire blight, anthracnose,alternaria blight, leaf spot diseases, brown rot, apple cedar rust, peach leaf curl, peach 23canker, stem blight, shothole, leafscorch, black rot, scabs and botrytis . Garden dust alsoprovides some repellency against a number of insects. The usual active ingredient isrotenone, which is extracted from the roots, leaves and seeds of Derris elliptica, locallyavailable in Malaysia24. This product can be mixed with water and applied as a spray orsprinkled over plants directly. Although most garden dusts are acceptable as an organicproduct, it can leave toxic residuals and would be harmful if applied too soon beforeharvest.9. Organic HerbicidesThe biggest single problem facing farmers in Malaysia is weed control. Organicherbicides based on vinegars and essential oils have not even come close to matchingconventional herbicides as the results of a US study indicate, shown in the figure below25.Most, organic herbicides on the market, generally rely on acidic pH and burning out thegrasses, which tend to produce spasmodic results. In a country like Malaysia, weedcontrol is a chronic problem, usually requiring very strong conventional herbicides tocounter extremely positive conditions for growth: warmth and high rainfall. In addition allorganic herbicides are general and non-selective at this point of time. Alternativepractices to using conventional herbicides are currently very limited and generally requirethe use of extensive labour, which is expensive, i.e., mulches, plastic covering, selectiveburning, etc26. Opportunities exist to develop efficacy improvements in organic herbicidesthrough other formulating routes like specific enzyme development.Comparison of a conventional Herbicide with an Organic Herbicide on the USMarket Product Reported Results* Control O 27 Round Up Pro 10 All-Down Organic28 Range 0.5 – 3.8
  • *1-10 with 10 = best after 10 daysConclusionThe advantages of focusing on natural product research and development for application inthe agriculture sector are many. Unlike, cosmetics, flavour and fragrance ingredients andpharmaceuticals, the costs of product registration are both cheaper and require much lessdata. Field efficacy trials for agricultural products are much cheaper and easier to managethan clinical trials for cosmetics and pharmaceuticals. The technologies, as discussed aboveare much easier and straight forward. The global agricultural market is much morefragmented than the flavour and fragrance and pharmaceutical industries, so this would allowmuch more ease in market entry for any future commercial product produced. Also of greatimportance, is that this region is one of the largest consumers of agricultural inputs, so it is notnecessary to crack the European or US market straight away – there is plenty of business forthese products locally before we go abroad, which is the opposite case for cosmeticingredients, flavour and fragrance materials and pharmaceutical ingredients.Competitive advantage can be gained through standardisation methods and in Malaysia wehave the expertise to undertake this without outside assistance. Through standardisation andproprietary methods of manufacturing and processing to a standard set by us, intellectualproperty can be developed, which will further develop barriers to entry to other potentialproducers. The established multi-national companies in the agricultural input market, have abig disadvantage. These organisations are geared to factory and process manufacturing. Incontrast, the production of organic products tends to rely on securing sources of materials,which are firmly under our control. This advantage, will give a local manufacturer time to startup, develop the market, before large scale competition enters the market with directsubstitutes.The new age farming discussed at the beginning of this article is rapidly growing and themarket for agricultural input products is in excess of USD 50 billion and steadily growing. Thisis surely an opportunity that Malaysia’s natural product, biotechnology and agriculturalresearchers could focus on.1 Hunter, M., The use of natural fragrances in cosmetics – should it be considered?, Cosmetics,Aerosols & Toiletries in Australia, Vol. 19, No. 3., (1996), P. 39.2 BBC, GM Crops: An Action Network Briefing, http://www.bbc.co.uk/dna/actionnetwork/A2418509(accessed July 2006)3 The World of Organic Agriculture 2004-Statistics and Future Prospects, February 2004.www.soel.de/inahlte/publikationen/s/s_74.pdf (accessed January 2006)4 Published by the Natural Marketing Institute, in partnership with the Organic Trade Association,http://www.ota.com/consumer_trends_2001.htm (accessed January 2006)5 The Global Market for Organic Food & Drink, July 2003, Organic Monitorwww.organicmonitor.com/700140.htm (accessed January 2006)6 Ramli, B., The development of organic farming in Malaysia, paper presented at the Workshop onGreen Productivity and Natural Farming, Seoul, Korea, organised by Asian Productivity Organisation(APO)7 Sullivan, P., Applying the Principals of Sustainable Farming: Fundamentals of SustainableAgriculture, Davis California, ATTRA, 2003, P. 2.8 University of Nebraska Lincoln, The Department of Biological Systems Engineering,http://bse.unl.edu/9 This is the local name given to enzymes as a generic term10 Hunter, M., and Yothangrong, K., The Emerging Cosmetic & Personal Care Cottage Industry inThailand: The Production of Enzyme Based Products, Cosmetics, Aerosols & Toiletries in Australia,July 2006, in press.
  • 11 Registered Trademarks of Biomor http://www.biomor.com/solutions.htm#e12 Photo courtesy of Mr. Peter Tirosh13 Currently 5 patents (1 approved and 4 pending)14 Private communication with Mr. Peter Tirosh, owner15 Naidu, B., P., Production of betaine from Australian Melaleuca spp. For use in agriculture to reduceplant stress, Australian Journal of Experimental Agriculture, 43, 2003, pp. 1163-1170,16 Bodapati, P., Naidu, P. and Cameron D., F., Reducing Plant Stress Using Australian Melaleuca, AReport for the Rural Industries Research and Development Corporation, Canberra, RIRDC, 1999.17 Brophy, J. and Doran, J.C., Essential Oils of Tropical Asteromyrtus, Callistemon and Melaleucaspecies, Canberra, Australian Institute for Agricultural Research, (1996), P. 63.18 Yaacon, K.B., Abdullah, C.M., and Joulain, D., Essential Oil of Melaleuca cajuputi, Paper presentedto the 11th International Congress of Oils, Fragrances and Flavors, New Dehli, India, 12-16th November1989.19 Report of an Ad Hoc Panel of the Board of Science and Technology for International Development,Neem; A Tree for Solving Global problems, Washington D.C., National Academy Press, 1992, P. 34.20 Ibid., P. 3921 Australian Patent No. 61764822 CH3(CH2)30CH323 http://www.ghorganics.com/Garden_Dust_Insecticide_Fungicide.html24 Burkill, I. H., A Dictionary of the Economic Products of the Malay Peninsula, London, Governmentof the Straits Settlements, Volume 1, 1934, pp. 795-808.25 Ferguson, J.J., Evaluation of Organic Herbicides, Horticultural Sciences Department, University ofFlorida, Gainesville,http://www.hos.ufl.edu/jjfnweb/organicnl/Dec03/JJF%20Evaluation_Art1.htm(accessed July 2006)26 Sivapragasam, A., Management of Pests, in Aini, Z., Sivapragasm, P., Vimala, M.N. and MohamadRoff (eds.), Organic and Vegetable Cultivation in Malaysia, Kuala Lumpur, MARDI, pp. 109-110.27 Registered Trademark of Monsanto.28 http://alldownherbicide.com/