Student Handbook for Agro-chemicals PP21: Agro-chemicals and Weed Science Dr. Jamba Gyeltshen Sr. Lecturer & Dean of Student Affairs College of Natural Resources, Lobesa October 2008 PREFACE This course handbook on Agro-chemicals is for students who follow a course module on Agro-chemicals. It contains information related to all practical aspects of pesticides application including understanding of pesticide label, preparation of spray, operation and maintenance of spray equipment, safe handling and disposal of pesticides, and pesticide profiles. The content has been largely drawn and adapted from a manual put together by G.G.M. Schulten, a consultant fielded by the NPPC during the Integrated Pest Management Development Project in December 1999. Educational websites have also been used and indicated in the footnotes. I have made few modifications to suit the purpose of this handbook and mainly arranged the topics into a structure convenient for students. CONTENTS 1. THE USE OF PESTICIDES IN BHUTAN ........................................................................ 1 2. CLASSIFICATION OF PESTICIDES .............................................................................. 5 3. PESTICIDE FORMULATION ........................................................................................ 10 4. PESTICIDES LABELS ..................................................................................................... 16 5. PESTICIDE TOXICITY ................................................................................................... 21 6. SAFETY PRECAUTIONS ................................................................................................ 25 7. EMERGENCY MEASURES IN CASE OF PESTICIDE POISONING ...................... 39 8. SPRAY EQUIPMENT AND MAINTENANCE .............................................................. 43 9. THE USE AND MAINTENANCE OF SPRAYERS ....................................................... 51 10. CALIBRATING HAND-OPERATED SPRAYERS ..................................................... 53 11. MEASURING PESTICIDES .......................................................................................... 57 12. CALCULATIONS OF PESTICIDE............................................................................... 61 13. APPLICATION OF PESTICIDES................................................................................. 63 14. PESTICIDE PROFILES ................................................................................................. 68 1. THE USE OF PESTICIDES IN BHUTAN Background Until 1989 all types of pesticides irrespective of their toxicity and persistence, were used in Bhutan. From 1990, government restricted import of highly toxic and persistent pesticides and prohibited private imports. The pesticide subsidy was reduced stepwise from 100% to 0% by 1995. Uncontrolled imports and free supply of pesticides in the past led overuse of often very toxic insecticides and an accumulation of obsolete pesticides. In 1995 a total of 66 tons of obsolete pesticides was collected including around 13 tons of fungicides, 23 tons of herbicides and 30 tons of insecticides. These pesticides were re-packed and disposed off at a huge cost. Since 1984 the pattern of pesticide changed considerably as shown in Figure 1. There was a strong decrease in the use of insecticides and fungicides while the use of herbicides increased. The likely explanation for this change is that when pesticides were fully subsidised there was a general overuse. When subsidies were phased out gradually, the demands decreased. Herbicides, however, were never subsidized. Now farmers have to pay the full price, they buy only pesticides that give a good return on their investment. Labour shortage and cost of labour apparently stimulate the use of herbicides. Fig. 1. Pesticide inputs in Bhutan (active ingredients) 1984/85 to 1998/99. Please note that up to 1989/90 farmers bought herbicides directly from the suppliers. Actual herbicide inputs up to 1989/90 are therefore higher than presented. Herbicides have never been subsidized. Pesticide procurement and supply in Bhutan NPPC is entrusted with the responsibility of procuring and supplying pesticides. In the past, DAOs were carrying out the task. As a result, all types of pesticides irrespective of their nature of persistence, toxicity to humans, natural fauna and aquatic life were procured and used. Past system of procurement and supply Extension agents submitted demands to DAOs on adhoc basis. DAOs compiled and sent it to Plant Protection Centre. Compilation of indent from all Dzongkhags and institutions were done at the PP centre. Quotation was called for various pesticides and consequently they were supplied as per the indent. Problem: 1. No proper record keeping as to where all the pesticides had been used. 2. Misuse or abuse of pesticides due to free-of-cost supply. 3. Accumulation of outdated pesticides. 4. Many highly toxic and persistent chemicals were procured. 5. Most of the pesticides remained in stores at Dzongkhag Head quarters without being used where they were necessary. Out of the various chemicals procured and used in the country, the following chemicals, for their toxic nature and other unfavourable properties have been stopped for use. 1. Aldrin 2. Aluminium Phosphide 3. BHC 4. Captafol 5. Carbofuran 6. Ekalux 7. Agallol 8. Methyl Parathion 9. Red Lead 10. Thimet 11. Temik 2 Present system of procurement and supply Procurement Extension Agents collect a rational demand from farmers and put it up to the DAO. DAOs forward the demand after careful scrutiny keeping in view the pricing policy and cash-andcarry system. Demands are compiled at the NPPC. Quotations are called from dealers of manufacturing companies in India, through advertisement in Kuensel ensuring fair participation and stiff competition. Freshly prepared materials of appropriate pack size are procured and supplied. Distribution: Most of the pesticides except herbicides are distributed from NPPC store to Dzongkhag Head Quarter for the quantity for which the amount was paid in advance. However, under certain situations supplies are made on credit. Herbicides like Butachlor, Sencor, NC311, Mogeton, Sanbird are sold through the Commision Agents. Advantages: 1. No accumulation of waste 2. Fresh stock available 3. Quantity supplied went down 4. No misuse as subsidy has been removed 5. Less environmental pollution 6. Low risk to applicator 7. Chemical is cheaper. 8. No outstanding with Dzongkhags 9. Suitable pack size for small holders. Sometimes due to financial implications, Extension agents do not put up the indent for pesticides. As a result, when pest outbreak occurs, crop is already damaged before the chemical reaches from NPPC. Limited choice of chemicals as the range has been narrowed down.(e.g. soil insecticides). Changes: With the introduction of the pricing policy since 1990, demand seems to have drastically reduced for all pesticides except herbicides. The demand for herbicides, especially Butachlor, has gone up tremendously. Sustainability: NPPC has a revolving fund of Nu.5 million. Half of this amount is invested in fixed deposit and the interest accrued thereby strengthens the revolving fund and make it sustainable. Limitations: For practical reasons, chemicals could be bought from India only. As a result, many of the popularly used pesticides elsewhere are not available. Exceptions:- Japanese herbicide through KR-II grant; Prochloraz - seed treatment chemical for Druk Seed Corporation from Germany;Japanese fungicide for blast control. 3 Pesticides available in Bhutan1 I. INSECTICIDES Pack Size Rate per unit 1 Sl. No Chlorpyrifos 20 EC Products 100 ml 19.00 2 Cypermethrin 10 EC 100 ml 22.00 3 Dimethoate 30 EC 100 ml 25.00 4 Malathion 50 EC 100 ml 18.00 5 Malathion 5 D 5 kg 125.00 6 Fenvalerate 0.04 D 1 kg 19.00 7 K- Obiol 2.5 WP 1 kg 1246.00 8 Bacillus thuringiensis 100 gm 108.00 II. FUNGICIDES Pack Size Rate per unit 1 Sl. No Captan 50 WP Products 500 gm 177.00 2 Carbendazim 50 WP 500 gm 240.00 3 Copper Oxychloride 50 WP 500 gm 78.00 4 Mancozeb 75 WP 500 gm 95.00 5 Ediphenphos 50 EC 1 lt. 150.00 6 Isoprothiolane (Fugi-one) 500 gm 150.00 7 Probenazole 8 GR (oryzernate) 8 Kasurabcide 71.2 WP (Kasugamycin) 9 Pyroquilon 5 G (Coratop) 3 kg 38.00 10 Tridemorph 80 EC 100 ml 110.00 11 Hexaconazole 5 EC 100 ml 69.00 12 Blasticidin 1 EC 500 ml 150.00 13 Kitazin 48 EC 500 ml 150.00 14 Copper Sulphate 500 gm 41.00 15 Ridomil 72 WP 100 gm 158.00 16 Calcium Hydroxide 500 gm 94.00 17 Carboxin 75 WP 25 kg 37,485.00 18 Baycor 100 gm 201.00 Pack Size Rate per unit 3 kg 38.00 500 gm 150.00 III. HERBICIDES Sl. No Products 1 Glyphosate 41 EC 1 lt. 281.00 2 Oxyflourfen 23.5 EC 1 lt. 1365.00 3 Metribuzin 70 WP 100 gm 200.00 Pack Size Rate per unit 10 gm 6.00 Pack Size Rate per unit 1 lt. 674.00 IV. RODENTICIDES Sl. No 1 Products Zinc Phosphide 80W/W V. ACARICIDES Sl. No 1 Products Danitol 1 EC VI. NON-TOXIC Pack Size Rate per unit 1 Sl. No Sandovit (sticker) 1 lt. 135.00 2 Linseed oil 2 lt. 99.00 3 Tree spray oil (TSO) 210 lt. 69.00/lt. 4 Protein hydrolysate 100 gm 104.00 1 Products From the website of the Ministry of Agriculture. www.moa.gov.bt 4 2. CLASSIFICATION OF PESTICIDES Pesticide is a general term used for any substance or mixture of substances intended for preventing, destroying, repelling or mitigating pests including insect, rodents, fungi, bacteria, nematodes and weeds. Also included under pesticides are compounds used as repellents, attractants, anti-feedants etc. In legal terminology pesticide may be defined as “any substance used for controlling, preventing, destroying, repelling, or mitigating any pest”. 1. Classification of pesticides based on type of pests controlled Algicides Control algae in lakes, canals, swimming pools, water tanks, and other sites. Antimicrobials Kill microorganisms (such as bacteria and viruses). Attractants Attract pests (for example, to lure an insect or rodent to a trap). (However, food is not considered a pesticide when used as an attractant.) Biopesticides Biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. Biocides Kill microorganisms. Fungicides Kill fungi (including blights, mildews, molds, and rusts). Fumigants Produce gas or vapor intended to destroy pests in buildings or soil. Kill weeds and other plants that grow where they are not wanted. Herbicides Insecticides Kill insects and other arthropods. Miticides (also called acaricides) Kill mites that feed on plants and animals. Microbial pesticides Microorganisms that kill, inhibit, or out compete pests, including insects or other microorganisms. Molluscicides Kill snails and slugs. Nematicides Kill nematodes (microscopic, worm-like organisms that feed on plant roots). Ovicides Kill eggs of insects and mites. Pheromones Biochemicals used to disrupt the mating behavior of insects. 5 Repellents Repel pests, including insects (such as mosquitoes) and birds. Rodenticides Control mice and other rodents. The term pesticide also includes these substances: Defoliants Desiccants Insect growth regulators Cause leaves or other foliage to drop from a plant, usually to facilitate harvest. Promote drying of living tissues, such as unwanted plant tops. Disrupt the molting, maturity from pupal stage to adult, or other life processes of insects. Plant growth regulators Substances (excluding fertilizers or other plant nutrients) that alter the expected growth, flowering, or reproduction rate of plants. Reference: Dr. Larry D. Schulze, Extension Pesticide Coordinator, Master Gardener Inservice Training,Cooperative Extension; University of Nebraska-Lincoln, USA. (http://pested.unl.edu/pesticide/pages/index.jsp?what=pageObjD&pageObjId=62 accessed on 13/10/08) Biopesticides2 Biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, neem oil and baking soda have pesticidal applications and are considered biopesticides. With increasing awareness and health concerns, more and more biopesticide products are getting into the market. Biopesticides fall into three major classes: (1) Microbial pesticides consist of a microorganism (e.g., a bacterium, fungus, virus or protozoan) as the active ingredient. Microbial pesticides can control many different kinds of pests, although each separate active ingredient is relatively specific for its target pest[s]. For example, there are fungi that control certain weeds, and other fungi that kill specific insects. The most widely used microbial pesticides are subspecies and strains of Bacillus thuringiensis, or Bt. Each strain of this bacterium produces a different mix of proteins, and specifically kills one or a few related species of insect larvae. While some Bt's control moth larvae found on plants, other Bt's are specific for larvae of flies and mosquitoes. The target 2 Master Gardener Inservice Training Cooperative Extension; University of Nebraska-Lincoln Dr. Larry D. Schulze, Extension Pesticide Coordinator (http://pested.unl.edu/pesticide/pages/index.jsp?what=pageObjD&pageObjId=62 accessed on 13/10/08) 6 insect species are determined by whether the particular Bt produces a protein that can bind to a larval gut receptor, thereby causing the insect larvae to starve (2) Plant-Incorporated-Protectants (PIPs) are pesticidal substances that plants produce from genetic material that has been added to the plant. For example, scientists can take the gene for the Bt pesticidal protein, and introduce the gene into the plant's own genetic material. Then the plant, instead of the Bt bacterium, manufactures the substance that destroys the pest. The protein and its genetic material, but not the plant itself, are regulated by EPA. (3) Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms. Conventional pesticides, by contrast, are generally synthetic materials that directly kill or inactivate the pest. Biochemical pesticides include substances, such as insect sex pheromones, that interfere with mating, as well as various scented plant extracts that attract insect pests to traps. Because it is sometimes difficult to determine whether a substance meets the criteria for classification as a biochemical pesticide, EPA has established a special committee to make such decisions. 2. Classification of pesticide based on mode of action Contact poisons As the name implies, the pesticide will have its effect only on contact with the target pest. Therefore it must be applied in such a way and at such a time as to ensure a direct contact. Larval stages are especially vulnerable to contact poisons. eg. Malathion, Cypermethrin (also a stomach poison), Dimethoate (also systemic), Chlorpyrifos (also stomach poison and has vapour action) Systemic insecticides Systemic insecticides are highly water soluble and as a result they are easily absorbed by growing plants through the roots, stem or leaves. Once absorbed into the plant, they are then translocated to untreated parts through the vascular system thereby making the whole plant poisonous. Systemic insecticides are particularly effective against sucking, boring and mining insects. Aphids, bugs, plant hoppers, scale insects, thrips, mites, borers and leaf miners can be better managed with systemic insecticides. Example: Dimethoate. Stomach poisons Stomach poisons generally enter a pest’s body through the mouth during feeding (ingestion) and are absorbed through the digestive tract. Fumigants The fumes or vapour given off by the insecticide usually gain entrance via the breathing mechanism of the insect, and frequently affect the nervous system. Fumigants are not usually used on growing crops, but are used for soil treatments, and in grain stores. 7 Suffocating materials These materials are usually oils that clog the respiratory mechanism of pests, eg. Tree Spray Oil (TSO) used to control scale insects. 3. Classification of pesticides based on chemical nature Most modern insecticides fall into one of four chemical types, i.e. organochlorine, organophosphate, carbamate, or synthetic pyrethroid. Organochlorine compounds DDT, Dieldrin, Aldrin, and BHC belong to this group. The use of mentioned insecticides has been banned in most countries because of their long persistence in the environment and the accumulation of their residues in the fatty tissue of man and other vertebrates. Some organochlorines have been shown to cause cancer in test animals, as well for being associated with other health problems. The acaricide Dicofol that belongs to this group is currently recommended in Bhutan for the control of mite pests. Its persistence is limited. Organophosphorous compounds Organophosphates can kill by contact, systemic or fumigant action or a combination of the three. They affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter. Being a nerve poison they can cause acute toxic reactions in humans. Although very efficient, they are not usually so persistent as the organochlorines. Some compounds, like Dimethoate have a systemic action in plants. Organophosphorous insecticides presently used in Bhutan are Chlorpyriphos, Dimethoate and Malathion. Certain fungicides such as Edifenphos also belong to this group. Carbamates These are insecticides that affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter. They do not persist in the environment or in the fatty tissue of animals. Some such as carbofuran are persistent, systemic pesticides with high toxicity. Synthetic pyrethroids Pyrethroids were developed as a synthetic version of the naturally occuring pyrethrins found in Chrysanthemums. They have been modified to increase their stability in the environment and possess quick knock-down effect but less toxic to mammals. Cypermethrin, Deltamethrin and Fenvalerate are synthetic pyrethroids used in Bhutan to control a number of insect pests. Fungicides Contact fungicides These compounds have a low acute toxicity to man, other vertebrates and insects. Widely used in Bhutan are Captan and Mancozeb. 8 Systemic fungicides Certain fungicides have a systemic action and are used to control a broad spectrum of fungal diseases, for example Carbendazim , Hexaconazole and Tridemorph; others are used to control a specific disease such as rice blast, for example, Isoprothiolane, Probenazole, Pyroquilon and Tricyclazole. Metallic compounds Copper oxy-chloride is an inorganic copper compound used as a contact fungicide. Antibiotics These are chemical substances, produced by microorganisms that have a fungicidal or bactericidal activity. Blastidicin and Kasugamycin are such antibiotics, temporary used in Bhutan to control rice blast. Herbicides Herbicides include components from different chemical groups. Most are relatively non-toxic to humans, but herbicides like Paraquat and Diquat are very toxic when ingested. Their use is not allowed in Bhutan. Herbicides such as Butachlor, Metribuzin, Oxyfluorfen, and Pendimethalin control weeds by contact while Glyphosate has a systemic action. Non-toxic compounds Certain oils such as TSO (Tree Spray Oil) can be used as an insecticide or acaricide. The oil penetrates the body of the insect or mite and kills it. These oils are used as “winter sprays” because of phytotoxicity. Sometimes a chemical like “Sandovit” is added to the spray mixture to better “stick” the spray solution to the leaves. 9 3. PESTICIDE FORMULATION Formulation Pesticides are rarely applied in their pure form because it would not be safe, convenient or economic to apply them in that form. The pure form needs to be first formulated (processed) as mixtures containing other ingredients that improve its properties of storage, handling and application. Pesticide formulation thus refers to the processing of a toxic compound by any method that will improve its properties of storage, handling, application, effectiveness and safety. A formulated product simply means something that is processed and ready for use. For example, dairy milk in its natural state is a liquid that cannot store long without going sour but when processed and formulated as milk powder such as Everyday®, Amulya or Milkmaid, it can be stored for long and is convenient for use. In the simplest sense, formulation means to put certain ingredients together (using a formula) to make a product or commodity with enhanced value. Why pesticides have to be formulated? At the chemical factories, synthetic pesticides come out in various forms: large crystals, lumps, flakes, and as viscous oils. These are known as Technical Grade material (TC) or Active Ingredient (A.I.). and they cannot be used in this highly concentrated form. Such products are not yet processed are considered as unformulated pesticides. These highly concentrated materials would neither be safe nor economic or convenient for application. It is not possible to get an even distribution essential for effective pest control. Therefore, the technical grade materials have to be processed into usable forms, usually called formulations, which can be distributed or sold for application. During the process of formulation the concentrated TC or AI is diluted by blending with “additives”. How pesticides are formulated? Since unformulated pesticides or pesticides in a raw form are highly concentrated, one of the most important steps in the formulation process is to dilute the concentrated technical material. If not diluted, it would neither be safe for handling nor fit (stable) for storage. It would not be convenient for spraying. Dilution of technical material to produce a formulated pesticide can be accomplished in several ways. Generally a formulated product has the following ingredients: Technical grade material (TC) or active ingredient (AI) Solvents Carriers Surface active agents Special additives Active ingredient /Technical grade material The TC or the active ingredient (AI) is the actual toxic component and therefore the most important ingredient in a formulation. Carriers The term carrier is generally used to denote the inert solid ingredients used to dilute the technical material, usually in dry formulations such as dusts, dispersible powders and granules. A typical carrier is pyrophyllite, an inert clay. 10 Solvents Solvents are liquid media in which the TC or AI are dissolved. The solvents may be miscible or immiscible with water (milk is miscible with water whereas diesel oil is not). Those solvents not miscible with water will require addition of another component known as the emulsifier or the surfactant. Surface active agents (surfactants) These are agents that reduce the surface tension and increase the wetting power of water. Soaps or detergents have these properties. The emulsifying agents or emulsifiers, wetting agents or wetters, dispersing agents or dispersants, foaming agents and spreading agents all belong to the group of surface active agents. A solution of surface-active agents in water differs from pure water in several ways. It firstly lowers the surface tension, enhances wetting power and dispersing properties. How surface tension is lowered? Surface-active agents have a characteristic structure which gives them unique properties. Their chain-like molecules have a part which is attracted to water (hydrophilic) and is water soluble; they also have a part that repulses water (hydrophobic) but is soluble only in organic solvents. In a watery solution, these molecules collect at the surface while pushing their hydrophobic tail-portion out of the water into the air. If the surfactant concentration is high, these molecules will cover the entire surface and lower the surface tension. Increasing the surface area of such a solution is much easier than increasing that of pure water. In other words its surface tension is much lowered. AIR WATER SURFACE WATER HYDROPHOBIC Figure: HYDROPHILIC The portion of the surfactant molecule that does not like (hydrophobic) water forces itself to the surface of a water solution thereby changing the characteristics of the surface. 11 How the wetting power is enhanced? The hydrophobic tails at the surface of the solution are the hydrocarbon groups in the surfactant molecules. Owing to their presence, the surface of the solution resembles the surface of a hydrocarbon or oil. Because the surface of a leaf is often covered with a layer of wax to minimize transpiration, the wetting of a waxy leaf cuticle is easier to achieve with oil than with pure water. This is the reason why a surfactant solution, with its oil-like surface, wets a leaf better than water does. Adding a surface-active agent to formulation thus improves its wetting power in solution. Reduction of surface tension and improvement of wetting power both play an important role in while spraying chemicals. They have a profound influence on the size of the spray droplets and on the spreading, retention and run-off of the spray liquid on the target surface. Leaf surface Figure: Wetting of leaf surface when wetting agents are not used Figure: Wetting of leaf surface after wetting agent is used How the dispersion properties are enhanced? A third characteristic of a surfactant solution is its dispersing property, which is related to the same phenomenon that causes the improved wetting power. Because water and oil are immiscible, when the two are mixed by stirring and shaking, the droplets of oil quickly form a layer on the top. When an emulsifier or a surfactant is added, the molecules of the surfactant will collect around the droplets of oil. The hydrophobic tails of these molecules then penetrate into the oil droplets, while their hydrophobic heads remain in the water portion of the solution. The congregation of surfactant molecules, in the so-called interface between water and oil cause a more-or-less stable situation in which the oil droplets remain dispersed in the 12 water, giving the water a milky appearance. This is called dispersion because the oil remains as microscopic sized droplets. Water oil Figure:Drawing of oil droplet in a surfactant solution Special additives These additives are used in a formulation or added separately into spray tank while preparing to spray. Examples: stabilisers – used to prevent the deactivation of a.i.; synergists – increases pesticide activity; wetters – to increase wetting power; oils – to reduce evaporation loss, to reduce wash off; assist penetration; defoamers – to prevent excessive foaming; thickeners – prevent formation of small droplets and therefore reduce evaporation and enhances viscocity, prevents runoff; colouring agents – reduce the possibility of accidents. Pesticide formulation codes The considerable increase in the worldwide manufacture of pesticide called for a harmonized (uniform) system for the designation of formulation. In 1978, a world-wide coding system was prepared under the co-ordination of the International Association of Pesticide Manufacturers (GIFAP); the system was last revised in 1989. The coding system consists of 2 letters for each formulation type: Group 1: Concentrates for dilution with water EC – Emulsifiable Concentrate SL - Soluble Concentrate SC – Suspendable concentrate SP - Soluble Powder WP - Wettable Powder WG/SG – Water dispersible Granules/Soluble Granules 13 Group 2: Formulations to be applied undiluted GR – Granules DP – Dustable Powder (dusts) UL – Ultra low volume (ULV) liquid Group 3: Miscellaneous formulations for special purpose RB – Ready to use Bait Definition of terms: Dispersion, emulsion, solution, suspension If we add oil into water, they do not mix well but instead form two separate layers. The oil which is light forms the upper layer. Such liquids are said to be immiscible liquids. On the other hand, when two liquids mix well (e.g. alcohol and water) they are said to be miscible. The molecules of the two liquids are well dispersed (spread out or scattered) and forms a stable situation and such a mixture of well dispersed liquid is known as dispersion. The dispersion of liquid in a liquid (e.g. oil-in-water) is called emulsion. Fine globules of an organic solvent containing the technical ingredient are dispersed in water. In a solution, no separate droplets can be formed because the dissolving process is complete at the molecular level. A suspension is the dispersion of a wettable powder (WP) or a water-dispersible powder in a liquid. EC – Emulsifiable Concentrate An emulsifiable concentrate is a solution of an active ingredient in a non-water miscible solvent. It contains an emulsifier to help the concentrate mix with water upon slight agitation and form an emulsion. It contains usually 15 to 50 percent of active ingredient that has to be diluted with water to form a solution in a spray tank. WP- Wettable Powder This type of formulation is also termed water dispersible powder, and is applied as a suspension after its dispersion in water. A wettable powder is a mixture of the active ingredient with powders and certain chemicals to improve its solution in water. Wettable powders are essentially dusts containing 25 to 50 percent of active ingredient and certain other chemicals, which have to be diluted in water to form a solution for spraying. GR- Granules Granules are defined as free flowing, ready-to-use, solid product of a defined granule size. Granular formulations are usually made by spraying a liquid concentrate of the technical grade material onto small pellets of some absorptive material. Uniform chips of broken bricks and coarse grains of sand are commonly used. This type of formulation can be used without application equipment and virtually any time of the day, since they can be applied even in strong winds without the problem of drift. They can also be drilled into the soil at planting time to protect roots against insects or to improve uptake of a systemic pesticide by the roots. 14 A disadvantage of the granular formulation is the high cost of manufacturing, handling, storing and transporting materials of low concentration. DP- Dustable Powder This type of formulation is a ready-to-use, free-flowing powder, generally with a low concentration of active ingredient, and suitable for dusting. Dustable powders are prepared by mixing and grinding the technical grade material together with an inert diluent such as pyrophyllite clay. If the technical grade material is a liquid, it has to be absorbed by the diluent before mixing and grinding. Ready-to-use baits (RB) Baits are formulations designed to attract and to be eaten by the target pest. They consist of a mixture of food, attractive to the pest, and a pesticide. The concentration of active ingredients in these baits is less than 5 per cent. They are used to control rats and mice. Ready-to-use bait that is available in Bhutan contains Bromadialone as rodenticide. Zinc phosphide is also used in baits to control rats and mice. This rodenticide is however, not available as a ready-to-use bait but farmers have to prepare the bait themselves and mix the rodenticide with it. Special baits A form of baiting used in Bhutan involves the addition of protein hydrolysate or Diammonium phosphate that attracts the Chinese Citrus Fly, a major pest of mandarins, to a spray solution of Malathion or Chlorpyrifos. The use of this bait makes it possible to treat only a small part of the tree to achieve effective fly control instead of treating the entire tree with a cover spray. 15 4. PESTICIDES LABELS3 Pesticides provide many benefits and improve the quality of life when they are used carefully and properly. But when handled in a careless manner they can endanger the health of the applicator, other people, animals, plants, or the environment. By law, certain kinds of information must appear on a pesticide label. The pesticide label provides valuable information about proper handling and use of the pesticide, potential risks the pesticide may pose, and instructions on how to minimize or avoid those risks. Every pesticide applicator has the responsibility to read and follow the label information so no harm will result from misuse or mishandling of pesticides. The pesticide label should be read at several critical times to make sure the expected benefits are realized and harm is prevented. People who use pesticides have the LEGAL responsibility to read, understand and follow the label directions. By law, certain kinds of information must appear on a pesticide label. Pesticide applicators have the legal responsibility to read, understand and follow the label directions. Pesticide labels will usually contain the following sections: Pesticide label The label is the most important source of information on the pesticide. It is a legal document that must contain legally specified information. Every pesticide product label should contain the following types of information if the product is meant for use on crops. 1. Product name/Trade name/Brand name 2. Type of pest controlled 3. Type of formulation 4. Ingredient statement 5. Net contents of the package 6. Name and address of the manufacturer, distributor or formulator 7. Registration or license number 8. Warning or “signal words” 9. Precautionary statements a) Hazards to humans and domestic animals b) Environmental hazards c) Physical and chemical hazards 10. Statement of practical first aid treatment 11. Use areas/Directions for use 12. Re-entry statement 13. Warranty statement/Expiry dates 14. Storage and disposal directions 3 North Dakota State University Agriculture and University Extension, http://www.ag.ndsu.edu/pubs/plantsci/pests/a1098w.htm 16 1. Product name: Every pesticide has a product name. Two types of names are given: a) trade name b) common/chemical name. a) Trade name is the most easily identified name on the label. It is the name usually used for advertisements. Each company has trade names or brand names for its products and when different manufacturing companies are involved in producing the same pesticide, they will sell them under different trade names although the active ingredient may be the same. b) Many pesticides have difficult chemical names and therefore some have been given a common name. e.g. the chemical name 0.0-diethyl 0-4-nitrophenyl phophoriate is given a common name Parathion. Examples of some product names include Punch, Roundup, Bavistin. 17 2. Type of pesticide: The label must indicate what type of pesticide the product is or what types of pests it will control. E.g. Fungicide, Insecticide, herbicide, rodenticide etc. 3. Type of formulation: Whether it is liquid (EC), solid (WP, Dust, GR), fumigant etc. 4. Ingredient statement: Each pesticide label must include the active and inert ingredients in the product. The list is written to show what the active ingredients are and the amount of each ingredient listed. The ingredient statement must list the official chemical names and/or common names for the active ingredients. Inert ingredients need not be named, but the label must show what percent of the total contents they comprise. Check the active ingredients when comparing pesticides. Many different pesticides will contain the same active ingredient. By purchasing pesticides according to the common or chemical name you will be sure you are getting the right active ingredient no matter what the trade name or formulation is. When comparing two different products with the same active ingredient, be sure to compare the amount of active ingredient in each product. Often products will contain the same active ingredient, but in different concentrations. Make comparisons based on use rates that contain the same amount of active ingredient. 5. Net contents: The net contents statement on the front panel of the pesticide label will tell you how much product is in the container. 6. Name and address of the manufacturer of the pesticide. 7. Registration number/License number: 8. Warning or Signal words: The keep out of reach of children warning statement is required to be on all pesticide containers. Many accidental poisonings and personal tragedies could be prevented by observing this precaution. The signal word indicates approximately how toxic the pesticide product is. Products that are highly toxic must display on the label the signal words DANGER-POISON along with a skull and crossbones symbol. Products that display only the signal word DANGER are corrosive and can cause irreversible eye damage or severe skin injury. Products that display the signal word WARNING are moderately toxic or can cause moderate eye or skin irritation. Products that display the signal word CAUTION are slightly toxic or may cause slight eye or skin irritation. 18 9. Precautionary statements: Precautionary statements identify potential hazards and recommend ways that the risks can be minimized or avoided. Types of precautionary statements include "Hazards to Humans and Domestic Animals," "Environmental Hazards," and "Physical or Chemical Hazards." a) Hazards to humans and domestic animals: The signal word is listed, followed by statements indicating which route(s) of entry (mouth, skin, lungs, eyes) are most likely to be harmful and must be particularly protected against. The label will then provide specific actions that can prevent overexposure to the pesticide. Protective clothing and equipment required to handle or apply the pesticide will be listed under the heading "Hazards to Humans and Domestic Animals." b) Environmental hazards: The environmental hazards section of the label warns of pesticide risks to wildlife, birds, fish, bees or to the environment and provides practical ways to avoid harm to organisms or the environment. c) Physical or chemical hazards: The physical or chemical hazards section of the label will tell you of any special fire, explosion, or chemical hazards the product may pose. 10. Statement of practical first aid treatment and Note to physicians: The statement of practical treatment lists the first aid treatment that should be administered to someone accidently exposed to the pesticide. The note to physicians provides emergency medical personnel with poison treatment information, antidotes, and often provides an emergency phone number to contact for further information. 11. Directions for use and use areas: The directions for use section of the pesticide label begins with the statement, "It is a violation of Federal law to use this product in a manner inconsistent with its labeling." Correct application of a pesticide product is accomplished by following the use instructions found on the label. The use instructions will tell you the pests which the manufacturer claims the product will control, the crop, animal, or site the product is intended to protect, when, where, how, and in what form the product should be applied, the proper equipment to be used, the correct dosage, mixing directions, compatibility with other often-used products, minimum time between the application and entry into the treated area for unprotected persons, and possible plant injury problems. 19 Labels for pesticides used on food plants will often list the days-to-harvest or preharvest interval (PHI), which is the minimum number of days between the last pesticide application and crop harvest. The pesticide is degraded during PHI so that pesticide residues, if present, will be at levels below tolerances established by EPA. 12. Re-entry statements When one can enter the sprayed area i.e. after how long? 13. Warranty statements/ Date of expiry: 14. Storage and disposal: All pesticide labels contain general instructions for the appropriate storage and disposal of the pesticide and its container. 20 5. PESTICIDE TOXICITY Pesticides are not only toxic to pests but they are also toxic or hazardous to man, his life-stock and the environment. Toxicity refers to the inherent toxicity of a compound to different forms of life. Hazard refers to the risk or danger of poisoning or environmental contamination when a pesticide is used. The potential extent of poisoning depends on: The toxicity of the pesticide. The dose of the pesticide, in particular its concentration. The route of entry or absorption by the body. The duration of the exposure. Measurement of toxicity Toxicity is normally measured by response to a single dose of pesticides entering the body of a test animal, usually a rat or rabbit. The units of measurement are milligrams of active ingredient of pesticides per kilogram of body weight. The relative toxicity of a pesticide is recorded as the “Lethal Dose” (LD50) value, a statistical estimate of a chemical dose that will kill 50 per cent of the test animals under stated conditions. As toxicity also varies with the route of absorption by the body, LD50 values may be determined for different routes of entry to the body. The result of pesticide testing by feeding is referred to as the oral LD50 for a specific test animal. Pesticides may also be tested by applying them on other parts of the body of the test animal. Because pesticides are selective in their action, reactions to them vary among different species of animals. Nevertheless, so long as the values are not considered absolute, LD50 values are a useful and internationally accepted way of classifying pesticides according to toxicity. In this context it is assumed that humans are at least as sensitive to pesticides as the most sensitive test animals. LD50 values and other factors are commonly used to classify pesticides as to the hazard that a particular pesticide presents to the user. Worldwide some different systems are in use showing however great similarity. The classification used by the World Health Organization is given in Table 1. This classification is followed by many countries, including Bhutan and also provides guidance on the labelling of pesticide formulations. 21 Table 1. The WHO Hazard Classification of Pesticides and Related Coding Acute LD50 (rat) - mg/kg body weight Clas s Hazard Statement Colour Pictorial Reference Oral Solid Dermal Solid Ia Extremely Red hazardous pantone red VERY TOXIC 199-c Skull & Crossbones 5 or less Ib Highly hazardous TOXIC Red pantone red 119-c Skull & Crossbones 5-50 10-100 II Moderately hazardous HARMFUL Yellow pantone yellow-c St. Andrew’s Cross 50-500 1001000 III Slightly hazardous CAUTION Blue pantone blue 293-c - 500-2000 over 1000 10 or less It should be kept in mind, however, that the acute toxicity of a formulated pesticide is less than that of the pure active ingredient, because the concentration of the active ingredient is less. The WHO classification of the toxicity of the active ingredients is however an easy reference for non-experts. 22 The approximate toxicity and hazard class of a formulation can be obtained from applying the following formula: Toxicity of formulation = LD50 of active ingredient X 100 / % of active ingredient in the formulation Example: Edifenphos (Hinosan) is an organophosphorous compound used as a preventive and curative fungicide. The acute oral toxicity of the pure compound is 150 mg/kg. (Class I B; Highly Hazardous) For the Edifenphos 50% EC formulation, the oral toxicity would be: LD50 (oral)= 150 X 100/50=300mg/kg Thus, Edifenphos 50% EC would be classified as Class II: Moderately Hazardous. (Table I) Besides creating hazards for man and livestock, pesticides may also endanger the environment. One main reason that the use of DDT, Aldrin and Dieldrin became prohibited in many countries was the long lasting damaging effect on non-target organisms, invertebrates and vertebrates. Most insecticides are very toxic to bees and should not be used during the flowering period. Many insecticides are also very toxic to fish and are therefore unsuitable for use near lakes or rivers and in paddy fields where fish farming is conducted. Pesticide residues A pesticide residue is that fraction of a pesticide, which because of its use, found its way into produce, soil or water and is present there either as the original pesticide or in degradation products of the pesticide. These residues in our food are a potential danger for our health. Experience has shown, however, that when the pesticide is used correctly and when a minimum period between application and harvest is observed, only minimal quantities of residue may remain that are of no danger to our health. The preparation of food and cooking further reduce any residues that may be present. Since agricultural produce may be exported or imported, internationally a need was felt to regulate potential problems with pesticide residues in the traded commodities better. Therefore the Joint FAO/WHO Food Standards Programme was launched that is being implemented by the Joint FAO/WHO Codex Alimentarius Commission. More than125 countries and many international organizations follow the recommendations and procedures, developed by this Commission. The Codex Alimentarius Commission recommends maximum residue limits (MRL’s). These are the maximum concentrations for pesticide residues resulting from the use of pesticides according to good agricultural practice, to be legally permitted or recognized as acceptable in or on food, agricultural commodity, or animal feed. The concentration is expressed in milligrams of pesticide residue per kilogram (mg/kg) of the commodity. The MRL values for food and vegetable oils are usually very much lower than those that would be unacceptable from a health point of view. The setting of MRL values by the Commission is a long process. Therefore, MRL values are not always available for all the pesticides that are being used. 23 It would be ideal if a country could regularly monitor pesticide residues in food and feedstuffs, agricultural commodities, soil and water. Pesticide residue analysis is however a very specialised and complicated science, requiring highly trained and very experienced personnel and expensive laboratory facilities. Therefore many countries, including Bhutan do not have established residue analysis facilities but in case of need, have the analysis done abroad in recognised laboratories. Reduction of hazards linked with the use of pesticides Essential for the reduction of hazards is the use of “Good Agricultural Practice” (GAP) in the use of pesticides. GAP is defined as the officially recommended or authorized usage of pesticides under practical conditions at any stage of production, storage, transport, distribution and processing of food, agricultural commodities and animal feed, bearing in mind the variations in requirements within and between regions. It takes into account the minimum quantities of pesticides necessary to achieve adequate control, applied correctly to leave a residue that is the smallest practicable amount and that is toxicologically acceptable. “Officially recommended or authorized usage” refers to the approved types of pesticides, pests to be controlled, formulations, dosage rates, frequency of application and pre-harvest intervals approved by the national authorities The “Pesticides Act of the Kingdom of Bhutan” will regulate the import, distribution and sale of pesticides in Bhutan. However, the National Plant Protection Centre (NPPC) at Semthoka will continue the import and distribution of pesticides till then. In ensuring the use of pesticides according to GAP, due consideration has to be given to: Using the pesticides on a need basis only and within an Integrated Pest Management (IPM) strategy. Selecting the least toxic and least persistent pesticides that will effectively control pests of economic importance. Selecting formulations that combine maximum efficiency of the selected pesticides with minimum risks. Recommending only the minimum amount of pesticide required to kill a specific pest or pest complex. Selecting the method of application that offers optimum control with minimum contamination of crops and the environment. Timing of the treatment in relation to susceptible stages in the development of a pest. Setting up of official pre-harvest intervals. (Minimum period between pesticide application and harvest) Training of farmers in the correct use of pesticides and related safety procedures is essential for hazard reduction inherent to the use of pesticides. These aspects including hazard reduction during storage and transport of pesticides are covered in pages 18-35. 24 6. SAFETY PRECAUTIONS Hazard reduction when handling, applying, storing and transporting pesticides Summary: Routes of entry of pesticides into human body: Inhalation (breathing) Skin (dermal absroption) Mouth (oral ingestion) When to take safety precautions a. b. c. d. e. Preparing spray solution Spraying the crops Storing the chemicals Transporting the chemicals Disposing empty containers a. Preparing the spray solution = Prepare the spray on a spot away from children and domestic animals = Read the label and its instructions carefully b. Spraying the crops = do not spray when it is too windy = do not eat or drink while you are still not finished with the spraying = do not spray without the protective gear: gloves, gumboots, mask, goggles etc. = leftover spray should never be retained in the spray tank; they should be disposed into a safe place =leftover spray should be always emptied into a safe place but never be stored in food containers c. Storing the chemicals = store in a well ventilated room = store out of reach of children (preferably under lock and key) = do not store along with food items and in food containers d. Transportation of pesticides = should not transport along with food items = leakage of containers should be checked e. Disposal of empty containers = empty containers should not be thrown all around, chances of being picked up by children for playing or by illiterate farmers for storing food items 25 = crush the containers and dump them into deep pits or in pit latrines from where they cannot be retrieved FIRST AID For chemicals on the skin: remove the contaminated clothes and wash your skin with soap and water. For chemicals in the eye: Splashes of chemicals, especially concentrated in the eye can damage the eye and also sometimes lead to poisoning. In all cases the eye must be washed with water. For swallowing or inhalation of chemicals: First aid measures vary; see entries under specific chemical groups. Where vomiting is recommended, this should be caused by putting a finger down the throat. Give water first to dilute the chemical and also enable the patient to vomit more. If symptoms appear: Always seek medical attention as soon as possible. In most cases, initial signs of poisoning are general symptoms such as nausea or headaches. Read the pesticide label4 Before you buy a pesticide, read the pesticide label to determine: If the pesticide will control the pest or pests. If the pesticide can be applied safely and legally under the application conditions. Where the pesticide can and cannot be applied. Necessary application and safety equipment. The amount of pesticide needed for the application (buy only the amount needed). Relevant restrictions for use of the pesticide. Compare different pesticide labels, because often several different products will control the same pest. A comparison of the labels and product prices will help select the product that controls the pest and is less toxic and/or less expensive. Before you mix the pesticide, read the label to determine: Protective equipment you should use. Compatibility of the pesticide with other products or additives. 4 North Dakota State University Agriculture and University Extension, http://www.ag.ndsu.edu/pubs/plantsci/pests/a1098w.htm 26 Amount of the pesticide to use. Mixing procedure. Before you apply the pesticide, read the label to determine: Safety measures you should follow. Procedures to follow to minimize potential harm to people, animals, plants or the environment. How to apply the pesticide. When to apply the pesticide (including the limitations about reentering a treated area and the minimum number of days that must elapse after the application before vegetables, fruits, or other crops can be harvested). Before you store or dispose of the pesticide or pesticide container, read the label to determine: Where and how to store the pesticide. Pesticide Label Information How to decontaminate and dispose of the pesticide container. Where and how to dispose of surplus pesticides. HAZARDS FOR HUMANS The use of pesticides is not without hazard for the farmer and his family, the extension agent, the consumer, and the environment. Pesticides become more hazardous through improper use. Users need to have a good understanding of the potential hazards of the various activities linked with the use of pesticides and on how to reduce these hazards. When handling or using pesticides, a number of precautions need to be taken to prevent entry of the pesticide into the human body. The pesticide may follow three routes: Through the skin. Through the mouth. Through breathing. Skin contact: Absorption of a pesticide through the skin when handling and applying pesticides is the most common cause of pesticide poisoning. This can occur not only through obvious splashes and spillage of concentrates directly onto the skin but also through the wearing of contaminated clothing, or by continuous exposure to spray. Chemicals pass readily from clothing to the skin, and can penetrate even through healthy unbroken skin into the body. Some parts of the body (the eyes, scalp, back of the neck, forehead and genital area) 27 absorb pesticides much faster than other parts. If the applicators work without aprons or with bare legs, the area exposed is thus several times larger than if protected with cloths. Special care must be taken in hot weather because sweating increases skin absorption. Oral ingestion:(swallowing) Ingestion of pesticides is particularly dangerous because the toxic substances are rapidly taken into the blood. Such poisoning may occur because of an accident or intentionally but mostly it is caused by carelessness. Well known examples are: eating, drinking or smoking without washing the hands after handling or spraying pesticides; using empty pesticide containers to store drinking water or food; keeping pesticides in unlabelled containers that are normally used to store water or food; storing pesticides within reach of children, etc Inhalation: Uptake by breathing may be dangerous if volatile chemicals are used in enclosed spaces. Few sprays and dusts are capable of passing along the airways from the nose into the lungs. Avoiding breathing spray mists, is however recommended. Hazards for the Environment Wherever pesticides are used, there is the possibility that due to human error or carelessness some may find their way outside the crop or the area that had to be treated with herbicides. The resulting contamination is a potential hazard for man, his livestock and his environment. Special risk areas are: Wells, ponds and watercourses. Cultivated land, where existing or following crops may be contaminated. Uncultivated land, supporting wild plants and animals. The most common causes of environmental contamination are spillage and leaks during transport, storage and application, improper disposal of containers and leftover pesticides, washing of containers and equipment, overdosing during application, and application in strong winds or close to susceptible areas such as open waters. REDUCTION OF HAZARDS Be Aware of the Toxicity of the Pesticide The different hazard classes of the pesticides used in Bhutan are given in Extension Leaflet No 5, the Extension Leaflets dealing with specific pests and in this manual. The label on the pesticide container also provides information on the toxicity of the pesticide and on the necessary safety precautions that have to be taken. The pesticide label: The “Pesticides Labelling Regulation” that will be enacted in the year 2000 regulates the kind of information that should be printed on the pesticide label (completed with a tie-on label if necessary). With regard to safety the following information should be provided: Warnings to prevent incorrect or inappropriate use. Use and conditions under which the product should not be used. 28 A statement of the safety interval between last application and harvest; use or consumption; access by humans or animals; sowing or planting of succeeding crops. Warning statements. The hazard statements and symbols according to the class of the pesticide (see table 1); the statement “KEEP LOCKED UP OUT OF REACH OF CHILDREN” and other statements as required. Safety precautions. Symptoms of poisoning, first-aid instructions, antidote statement and advice to doctors. In addition the toxicity of a pesticide has to be shown on the label as a colour band: Red is used to indicate a toxic to very toxic product (Class I A and I B); yellow indicates a harmful product (Class II) and blue a product that needs to be handled with caution.(Class III).Certain manufactures use a green band to indicate that there is no acute hazard when using the pesticide. Farmers must learn the meaning of the colour codes. Pictograms, stressing in simple pictures particular aspects of storage, handling and applying pesticides are becoming ever more in use. The most commonly used pictograms are shown in fig.5. It is essential that farmers understand the meaning of the pictograms. Keep locked away and out of STORAGE reach of Pictogram children Handling Handling dry Applicati liquid concentrate on concentrat ACTIVITY e Pictograms Wear gloves Wear eye protection Wash after use Wear boots Wear Wear protection respirator ADVICE over nose Pictograms and mouth Dangerou Dangerous/ s/ harmful harmful to to animals fish - do not contaminate lakes, rivers, ponds or WARNING streams Pictograms Figure 5. PICTOGRAMS FOR AGROCHEMICAL LABELS 29 Take Measures to Reduce Hazards from Pesticides It is the policy of the NPPC to recommend pesticides of a low toxicity in so far possible. However, no pesticide is without hazard and therefore precautions have to be taken when handling, applying, transporting and storing pesticides. Eating, drinking, smoking and chewing of doma or khaini should be avoided when handling or using pesticides, even when they have a low toxicity. A. HAZARD REDUCTION WHEN APPLYING PESTICIDES AND AFTERWARDS Buying Pesticides Never buy damaged packages or tins of pesticides. Never buy pesticides that are not in their original package or bottle. Protective clothing With all pesticides, users must minimise contamination. Even when nonspecific clothing is recommended on the Extension Leaflet or product label, lightweight clothing covering as much of the body as possible and boots should be worn. Trousers should be kept outside the boots. When additional protective clothing is recommended, it only needs the wearing of gloves and face masks or goggles. To help prevent skin contamination special clothing should be kept for use only during mixing and application. All clothing should be well washed after spraying. Measuring and Mixing Always stick to the recommended dose rates and dilutions. Higher doses will not produce better effects; lower doses will be less effective. Do not make mixtures of pesticides but when advised to do so by the NPPC. Concentrates, which mix easily with water, can be measured out and poured directly into the knapsack sprayer tank partly filled with water. Wettable powders are best pre-mixed with a little water before pouring into the sprayer tank. The tank should then be filled to the correct 30 level, and mixed well. Spray solutions used in power sprays should be well stirred with a stick to ensure good mixing. When measuring and mixing the following procedure is recommended: Use the pesticide only as recommended by the NPPC. Information on the correct use of pesticides and the safety precautions that have to be taken is given in the relevant Extension Leaflets and the pesticide label. Wear protective clothing as recommended. Do not measure out or mix pesticides in or near houses, or where livestock are kept. Keep children and animals away. Take care not to contaminate water supplies, or pools from which animals drink. Use suitable equipment. Measures: Khaini tins or other local measures as indicated in table 2.Where measures are supplied with packs, or marked upon them-Use them. Never use hands as scoops. Bucket or similar container with a stick for mixing. Never use hands or arms for stirring, Funnel, Filter. Pour liquids carefully to avoid spillage and use a funnel, if necessary. Handle dusts and wettable powders carefully to avoid fluffing-up. Stand so that the wind will blow dust or splashes away from you and not towards you. 31 Use proper equipment for measuring and mixing Never touch pesticides with bare hands Wash all equipment after use. Tip washing water into a hole in the ground, away from dwellings, wells, waterways and crops. Mixing vessels and measures used for pesticides must not be used for any other purpose. Close packages after use to prevent leaks or contamination and store safely, Always keep pesticides in their original containers; do not transfer into drink bottles or food containers. If spillage of pesticides occurs, deal with it as described on page 31. Disposal of containers Empty pesticide containers should not be used again as containers for food or drinking water for humans or animals because the complete removal of the pesticide by washing with water is impossible. These containers therefore will always remain a potential hazard. Metal cans should be washed, punctured, flattened and buried. Plastic cans should be washed, punctured, buried or burned. and carton boxes should be burned. Pesticide application in the field In Bhutan several application techniques of pesticides are used in the field depending upon the crop, the pest problem, the type of pesticide, the application equipment and the control strategy. There are, however a number of basic principles common to most situations, which enable users to reduce hazards as much as possible. Do not apply pesticides without adequate training. 32 Never allow children to apply or be exposed to pesticides; keep them out of areas being treated or areas that had been treated recently. Do not allow other workers in the field when pesticides are being applied. Use the pesticide as recommended in the Extension Leaflets. Give due consideration to weather conditions, particularly wind, which may cause spray drift. This may make the pesticide ineffective, by blowing it away from the target and it may be hazardous if it drifts onto the operator, other crops, water, animals or houses. Some pesticides are easily washed off by rain, and need a rain-free period after application to be effective. Do not apply pesticides when it is likely to rain Do not work in strong winds, Work so that any wind blows the pesticide away from operators and not onto them. Do not blow out clogged nozzles with the mouth but clean them with water or a soft probe, such as a grass stem. Keep people and animals out of freshly treated crops. Never leave pesticides and equipment unattended. Never leave pesticide containers open. Collect up all wastes such as empty packages or bottles for safe disposal. Hygiene. Personal hygiene is very important for all involved in pesticide application. After pesticide handling or application, hands and face should be washed with water and soap before eating, drinking or smoking. Do not eat, drink, smoke, chew doma or khaini during pesticide use or before washing. Do not touch face or bare skin with soiled gloves or hands during pesticide use. 33 Wash gloves (if worn) before removal. Wash thoroughly after work, and wash clothing used during the pesticide application each day. Ensure that all the safety precautions on the product label are observed. Re-entry to treated crops With some pesticides there should be a time interval between the treatment of the crop and a re-entry of the fields. This period allows for a reduction of the pesticide residues and prevents the risk of contamination when walking through the treated crop. Where such a risk exists, the NPPC will advise on the period of time that should be observed. Additional information can be found on the product label. It is a sensible precaution in any way to wait at least 24 hours after the last application to enter the fields again. Re-entry periods specified for humans also apply to domestic animals. Pre-harvest interval: (minimum period between pesticide application and harvest) The Extension Leaflets and the product label will specify the period that must elapse between the last treatment and harvesting of the crop. This period should be strictly observed to ensure that pesticide residues on the crop are within acceptable limits. B. HAZARD REDUCTION DURING STORAGE OF PESTICIDES Pesticides pose hazards to man and his environment from the stage of their manufacture until they are used, disposed off safely or completely degraded. Hazards are present during storage, transport and handling at the point of supply to users. It is therefore important that great care should be taken to minimize these hazards. During storage and transport the quality of the pesticides has to be maintained within acceptable limits until the pesticides are used. Storage at Dzongkhag Level A number of important measures have to be taken to minimize hazards and reduce wastage. They concern: Security. Maintenance of the pesticide stocks in good condition. Emergency precautions. Security: Pesticides must always be stored under lock and key in a secure place, out of reach of unauthorized people, children and animals. In most Dzongkhags, the NPPC has constructed special stores for the storage of pesticides. Where these have not been built and where a separate storage building is not available, pesticides must be stored in a well ventilated separate section of a building than can be securely locked and away from offices or places where people live. 34 Maintenance of stocks in good condition: The first step in maintaining pesticides stocks in good condition is to study the recommendations for the storage of the pesticides on the product label and to implement these recommendations as much as possible. The label should also give the expiry date of the product, after which the use of the product should not be allowed without the approval from NPPC. If there are any doubts on this, or on any technical aspect of storing a particular product, the nearest RNRRC or the NPPC at Semtokha should be contacted. To ensure that stocks of pesticides are kept in good, useable condition, due attention must be given to the following four points. The correct siting and construction of pesticides stores, to minimize deterioration due to climatic conditions. The correct positioning and stacking of drums, boxes and other containers to avoid damage and to facilitate inspection. The adherence to the principle of “first-in, first-out” when using the stocks. Regular inspections and keeping of records. Emergency precautions in stores Wherever pesticides are stored, and on whatever scale, precautions must be taken to prevent accidents and damage, and the consequent problems of waste creation and disposal. In the event that they may occur, provision must be made to deal promptly and effectively with: Fire. Spillage and leakage. Contamination of personnel. Fire: Pesticides, especially those formulated as flammable liquids, can present major fire hazards, and can give off flammable vapours at normal temperatures. Therefore good ventilation (at ground as well as at roof level) is essential Containers must not be left open. Leaks and spillages must be dealt with promptly. SMOKING AND THE USE OF NAKED FLAMES MUST BE FORBIDDEN INSIDE STORES. Heating and electrical installations and equipment should be constructed, installed and maintained according to proper explosion and fire safety requirements. Notices must be placed on the outside of pesticide stores stating “DANGER PESTICIDE; AUTHORIZED PERSONNEL ONLY”. Notices and symbols indicating “NO SMOKING; NO NAKED FLAME” must be prominently displayed inside and outside. Most important, these rules must be strictly enforced. Water must be immediately available, and buckets of sand or earth should be provided in all stores for the purpose of extinguishing small fires or for absorbing any spillages or leaks. Depending on the size of stores, one or more fire extinguishers must be available and must be checked regularly to ensure that they are properly charged. They should be located where they are easily reached in an emergency, normally next to the door. Gas masks, gloves and boots, for at least two people, must be permanently available, with easy access to, but not kept inside, the store. They should be checked and cleaned regularly. 35 Spillages and leaks: Spillages in stores are most likely to occur when inadequately sealed or damaged containers are being moved or when pesticides are being measured out from larger to smaller containers. If spillages or leaks occur, they must be dealt with immediately: Keep people and animals away. Don’t smoke or use naked lights near the spillage. Remove damaged packages and place them on bare ground, away from dwellings and water supplies, where soil will absorb the leakage. Use soil or sawdust to absorb liquids, sweep up carefully and bury in a place where there is no possibility of wells and waterways. Wear protective clothing during clean up operations. In case foodstuffs are contaminated, these should be destroyed by burying them deeply in a hole or by burning. Contamination of Personnel: Provided pesticide containers are kept in good condition and handled sensibly by trained personnel, contamination should not occur, but where it does immediate action has to be undertaken: Remove affected clothing. Thoroughly wash contaminated skin areas with soap and water. Seek medical advice as quickly as possible. Provide the medical attendant with the label of the container from which the pesticide came. Storage and Sale at RNRRC’s and Geog’s Most RNRRC’s and Geog’s will have a small store in their office premises, or very close to it, for storing pesticides. The principles of safe storage and handling are similar to those for larger Dzongkhag stores: In particular, Pesticides must be stored separately and away from all other materials, to avoid any possibility of contamination, or confusion with other materials. The pesticide store must always be locked to avoid theft and unauthorized access. Pesticides must be stored away from and out of reach of children, animals and unauthorized persons. Pesticides must not be stored in human or animal food storage areas, or near fires, stores, or lamps, and should not be kept in occupied rooms. The floor and walls of the store should be constructed with material that is impermeable to water and should not crack easily; concrete is preferable. The store must be dry and well ventilated. There should be adequate lighting, but pesticides must not be exposed to direct sunlight. Pesticides should be neatly stored on racks or pallets, as discussed above for storage in Dzongkhag stores. Stock must be rotated on the ”first-in first-out” principle to avoid expiry of shelf life, 36 Stores must be regularly inspected to ensure that both the store and its contents are in an acceptable condition. A pesticide must not be sold to a minor, usually any person below 18 years of age. Pesticides should only be sold in their original undamaged package or container. Users must be given clear and concise instruction on how to use the pesticide safely and effectively. Pesticide packs, when purchased by a farmer or other user should be packed in a plastic bag and must not be carried along with food. Damaged or expired pesticides must be kept separately for return to Dzongkhag stores and a notice ”NOT FOR SALE” placed above these containers. Notices must be placed on the outside of pesticide stores stating “DANGER PESTICIDES: AUTHORIZED PERSONNEL ONLY”. Notice and symbols indicating ”NO SMOKING: NO NAKED FLAME” must be prominently displayed inside and outside. Most importantly these rules must be enforced. Water must be immediately available and buckets of sand or earth should be provided in all stores for the purpose of extinguishing fires or for absorbing any spillages or leaks. Any spillages or leaks, or any contamination of personnel with pesticides, must be dealt with immediately as described earlier. Storage on the farm Many accidents with pesticides occur on the farm because the pesticides were not safely stored. In all farmer trainings the risks of unsafe storage of pesticides should be stressed. To prevent accidents it is essential that: Pesticides should never be stored in the living quarters. Pesticides are always kept in their original containers. Pesticides are kept out of reach of children and preferably locked in a separate cupboard or box. Pesticides are kept in such a way that they cannot be mistaken for food or drink. Pesticides are kept dry, but away from fires and out of direct sunlight. C. HAZARD REDUCTION DURING TRANSPORT OF PESTICIDES It is essential that careful consideration should be given to the methods used to transport pesticides from NPPC to Dzongkhag and from NPPC to Geog stores. Sensible procedures include: Do not load pesticides onto vehicles carrying passengers, livestock, foodstuffs and other materials for human or animal consumption or use. If this is unavoidable then 37 separate the pesticides as much as possible from passengers and the remainder of the loads. Always clean the vehicle after unloading. Pesticides must never be carried inside the passenger compartment of cars. They should be placed in the trunk of the car, in an outsize container, or, preferably, in a trailer. Those directly responsible for collection and transport (drivers, etc.) must know what their loads contain, and what action must be taken in the event of an emergency. Special care must be taken during loading and unloading to prevent damage to containers. Protruding nails, metal strips and wood splinters on lorry bodies must be hammered flat before loading. Always load packages the correct way up as indicated, and ensure that fragile packages will not be crushed. Do not unload large drums or other heavy packages by pushing them off the backs of lorries. They must be unloaded in a controlled way. Loads must be secured so that they cannot move about or fall off during transport. Leaking and contaminated packages must not be accepted for loading. 38 7. EMERGENCY MEASURES IN CASE OF PESTICIDE POISONING The symptoms of pesticide poisoning may appear more or less immediately after the exposure or may be built up over a period of hours or longer. (fig.8) Symptoms of pesticideComa poisoning Pinpoint pupils Convulsions Excessive tears Headache Blurred vision Dizziness Salivation Sweating Tightness in chest Rapid heart beat Pneumonia Elevated blood pressure Vomiting Cramps Diarrhoea Muscular fibrillation Tremor Muscular weakness 39 The different groups of pesticides may cause different types of poisoning, each needing a special treatment. The severity of the intoxication depends on the type of pesticide, the dosage and the period of exposure Mild poisoning: Headache, a feeling of sickness (nausea), dizziness, fatigue, irritation of the skin, eyes, nose and throat, diarrhoea, perspiration and loss of appetite. Moderate poisoning: vomiting, blurred vision, stomach cramps, rapid pulse, difficulty in breathing, constricted eye pupils, excessive perspiration, trembling and twitching of the muscles, fatigue and nervous distress. Severe poisoning: convulsion, respiration failure, loss of consciousness and loss of pulse. Pesticide poisoning may show symptoms of other disorders such as heatstroke, pneumonia, asthma, low blood sugar levels, or intestinal infections. The correct diagnosis has to be made by a physician. Signs of environmental contamination The immediate impact of environmental contamination may show as the sudden appearance of dead fish, birds, other vertebrates or domestic animals. The long-term effect can only be assessed by means of specialised studies. Any indications of environmental contamination should be reported immediately to the NPPC. First Aid: Management at Scene of Incident Speed is essential. Do not wait for expert help but Immediately call for medical assistance or bring the victim to a doctor and provide the doctor with all relevant information, in particular the cause of the accident, the suspected point of entry of the pesticide, the pesticide label with information on the active ingredient of the pesticide and recommendations on how to handle in case of poisoning, etc. At the same time a number of activities need to be undertaken while waiting medical attention. Avoid self-contamination during the activities. Terminate the exposure to pesticides by removing the person from the place of spillage or other contamination. Remove contaminated clothing quickly and completely. 40 Take of contaminated clothes Wash contamination from the body surface Remove pesticides from skin, hair and eyes by using large quantities of water. In case of eyes, hold eyelids apart and rinse thoroughly for about 10 minutes. If there is no water available, dab or wipe skin with paper or cloth. Check and monitor permanently if the victim is breathing adequately. The breathing must be sustained continuously. If breathing is inadequate, give artificial respiration. Keep the victim calm, as he may tend to be extremely agitated. Place the victim in a convenient position since poisoned victims may become unconscious, may vomit or the breathing may stop suddenly. Therefore, place the victim on his side with the head lower than the rest of the body and turned to one side. If the victim is unconscious keep the chin forward and the head back to ensure that breathing can take place. If water is lacking, wipe contamination Place unconscious person on his side, tilt the off head back Particular attention has to be given to the temperature control of the victim. If the victim feels very warm and sweaty, the victim should be cooled by sponging with cold water a victim that feels cold should be covered with blankets. 41 Control overheating with cold water Control cold with a blanket Vomiting, as a first aid measure should only be induced in case the chemical has been swallowed, is highly toxic and likely to be fatal. Induce vomiting by tickling the finger on the back of the patient’s throat. Use two fingers of the other hand to force the patient’s cheek between his teeth. This ensures that your finger is not bitten. After vomiting has occurred or if induction is unsuccessful, give three tablespoons of activated charcoal in a half glass water to drink. Repeat as often as possible until medical attention is obtained 42 8. SPRAY EQUIPMENT AND MAINTENANCE Lesson objective At the end of this lesson, you will be able to: Explain the principles of how sprayers function List the different types of sprayers Label the important parts of a sprayer: knapsack sprayers, rocker sprayer Explain the principle of operation of pumps in knapsack, rocker and pneumatic sprayer Explain the principle of operation of knapsack sprayers Explain the principle of operation of rocker sprayers Explain the principle of operation of pneumatic sprayers Differentiate between hydraulic pump and compression or pneumatic sprayers Maintenance and care of spray equipment Principles of how sprayers function A liquid spray is formed by any of the following methods: 1. When spray liquid is forced out of a tube or barrel using a piston or plunger (hydraulic sprayers). 2. When spray liquid is forced out by compressed air over a liquid (pneumatic sprayers) 3. When spray liquid is forced out using a blast of air (e.g mist blowers) Types of sprayers 1. Lever operated knapsack sprayers 2. Compression or pneumatic sprayers 3. Rocker sprayers 4. Foot (pedal) pump sprayer 5. Others: motorised knapsack sprayers, spinning disc sprayer, mist blowers, birkys, spinning discs) 1. Lever-operated knapsack sprayer A knapsack sprayer is suitable for small plantings up to an acre in size. This sprayer is entirely manual and is carried on an operator's back. Also called a backpack sprayer, the knapsack sprayer is designed to be as light as practical. The parts of the knapsack sprayer are the same as those found on most sprayers: a tank to hold the spray mix; a pump to produce pressure and flow; a regulator to control the flow; and at least one nozzle to atomize the spray mix (Figure 2.2). The commonly available knapsack sprayer in Bhutan is the lever-operated shoulder-pump knapsack sprayer. It is made of stainless steel tank with a tank capacity of about 12 to 14 liters. Continuous pumping is required to operate the sprayer. The sprayer is 43 strapped and carried on the back like a backpack. Inside the sprayer tank is the pump assembly with a pressure vessel enclosing the pump cylinder. The pump is operated by one hand while the lance and the nozzle is directed by the other. Between 20 to 30 pumping strokes per minute are required to produce a fairly even spray. This sprayer is not suitable for spraying tree crops but are convenient for low crops such as the vegetable crops. The sprayer is also suitable for applying herbicides. The distribution system includes an on-off valve, one or more nozzles on a wand. The time and energy needed to use a knapsack sprayer on fruit trees limits the device to small plantings. When labor is of minimal consideration, such as with homeowners and hobbyists, the knapsack sprayer can be effective. Its size, however, is not practical for applying high rates of water per acre. Considerable practice is required to obtain thorough coverage of trees without overspraying, which creates wasteful runoff and may increase the risk of phytotoxicity. A great deal of skill is needed to obtain a uniform application. Application rates, walking speeds, and coverages also will vary with operator fatigue caused by temperature conditions, the time of day, the slope of the terrain, and the walking surface. In addition, the risk of overspraying and underspraying is increased because the knapsack sprayer uses a small volume of water. Extra care should be given to coverage and uniformity. The sprayers have a built-in piston or diaphragm pump that is operated by hand. Some models can be adapted to either right- or left-hand pumping; the other hand is needed to operate the flow-control valve and the wand. The chamber that pressurizes the chemical liquid is very small, so the operator must pump while walking and spraying. When the hand lever is operated and piston moves up and down. During the upward stroke, spray liquid is drawn into the cylinder through an inlet ball-valve at the bottom; on a downward stroke of the plunger, the spray liquid is forced into the pressure vessel through an outlet ball-valve. Air trapped above the liquid in the pressure chamber is compressed by the incoming liquid. The compressed air forces the liquid out through the lance and the nozzle. Parts of a typical lever operated knapsack sprayer 1. Tank 2. Lever 3. Funnel/lid/strainer 4. Pump assembly (Pressure vessel; pump cylinder; piston; valves; strainer) 5. Delivery port 6. Spray hose 7. Cock 8. Grip 9. Lance 10. Nozzle 44 45 46 47 2. Compression or pneumatic sprayers This type of sprayers does not need to be pumped continuously like the shoulder pump sprayers. The sprayer has a cylindrical tank in which air is pressurized with a plunger pump. The entire tank needs to be air-tight as it has to act as a pressure vessel. The tank should be filled only about 75% of the total volume so that there is some space above the liquid for pressurizing air. The sprayer is pumped before spraying and no pumping is required during actual spraying. To produce a fairly uniform and even spray, the sprayer should be pumped at 48 regular intervals or as and when the operator notes a drop in pressure. The lid of the sprayer should not be removed without first releasing the built up pressure as there are chances of liquid spurting out under pressure. 49 3. Rocking sprayer It is known as a rocking sprayer because the pump is operated back and forth in a rocking motion. Two persons are required to operate this sprayer: one to pump and the other to spray. The rocking sprayer does not have a built-in tank but the suction hose pipe draws in liquid from a bucket. This sprayer needs long hoses up to 6 m and pressure is good enough to direct spray against tall trees. Therefore this sprayer is good to use in the orchards. Parts of rocking sprayer 1. Pump assembly: pump barrel, plunger or piston; inlet ball valve and outlet ball valve 2. Pressure chamber/vessel 3. Suction hose/suction line 4. Strainer 5. Delivery hose/delivery line 5. Spray lance 7. Trigger cut-off valve 8. Nozzle 50 9. THE USE AND MAINTENANCE OF SPRAYERS Two types of sprayers are presently in common use. 1. The lever-operated Knapsack Sprayer is mainly used to spray low crops. This sprayer consists of a Tank, a hydraulic pump assembly and a Discharge Line. The pump assembly has a pressure vessel in which the spray liquid is loaded. The capacity of the tank of the sprayers is mostly 12 or 14 litres. 2. The Rocking Sprayer is mainly used to spray orchards. The sprayer consists of a Pump, a Pressure Vessel, a Suction Hose and Spray Lances. The sprayer is handoperated by one person while the spraying is done by a second person. By moving the lever of the sprayer, the spraying mixture is sucked from the bucket or container with the spraying mixture via the suction hose into the sprayer and brought under pressure in the pressure vessel. From there the liquid will be discharged via the spraying lance. Besides above described sprayers, there are also other sprayers in use, including motorized sprayers but in limited numbers only. The Spray Nozzle is the outlet of the sprayer. The proper selection and operation of spray nozzles are of key importance for the correct application of the pesticides. The nozzle determines the amount of spray applied to a given area, the uniformity of the applied spray, the coverage obtained on the sprayed surfaces and how much drift occurs. Nozzles can be available in different materials. Brass nozzles are the most commonly used in Bhutan. They are cheap but wear rapidly when used to apply abrasive materials such as wettable powders. Nozzles made from stainless steel are much stronger but more costly. There are many different types of nozzles. The “hollow–cone type nozzle” is the most commonly used nozzle in Bhutan.(Fig.4) This nozzle produces a circular pattern with almost no spray droplets in the centre. This type of nozzle is very suitable for spraying crops against insect pests and diseases. The “flat-fan type nozzle” gives uniform distribution across the entire width of the spray. This even pattern makes it suitable for band spraying in pre- and post-emergence herbicide applications. These nozzles are presently not available in Bhutan. Maintenance of Spraying Equipment Sprayers are costly but with good maintenance they can provide a good service for many years. When buying a sprayer always an operational manual should be obtained with instructions on how to assemble, use and maintain the sprayer. The following points should be observed when using sprayers: 51 Always use clean water for diluting the pesticide. Make sure that the spray liquid is properly mixed. Load the sprayer with the pesticide solution through a strainer (filter or sieve) in order to avoid clogging of the nozzle. Do not spill the spraying solution over the tank or any part of the sprayer to avoid corrosion and contamination of the operator. When the spraying operation is finished, empty the spray tank of all remaining pesticides by spraying what remains on the target crop. Fill the tank with clean water and some soap and shake vigorously. Operate the sprayer for about five minutes to clean the sprayer tank, tubes and nozzle. Remove the nozzle after some minutes and spray again to speedup the cleaning process. Repeat this procedure with clean water till the sprayer is considered clean. Remove as much water as possible and oil moving parts as required before storing the sprayer. Special attention should be given to the cleaning of the nozzle: Dismantle the nozzle by unscrewing the nozzle cap from the nozzle body and removing the nozzle tip and strainer. Clean the hole in the nozzle tip by back-flushing with clean water. If this is not possible, use a small brush or soft wire without damaging the tip. Clean the strainer with water. Assemble the nozzle. Things not to do when cleaning nozzles: Never use sharp objects to clean the mouth of the nozzle or the screen. Never put a nozzle or screen to your mouth to blow it clean. Do not over tighten a nozzle cap on the body. Replace a nozzle or strainer if it cannot be cleaned easily or is damaged by abrasion. Do not blow out clogged nozzles with your mouth Clean them with water or a soft probe. 52 10. CALIBRATING HAND-OPERATED SPRAYERS What is CALIBRATION? To CALIBRATE means to mark or correct the units of measurement on (the scale of a thermometer or some other measuring instrument); the action of calibrating is known as CALIBRATION. For instance, if we want to make a 30 cm scale out of a small piece of sawn timber, we would mark the different units on this home-made scale by using the original scale or a measuring tape. This very act of marking with units is known as CALIBRATION. Calibrating a hand-operated sprayer, however, has a slightly different meaning from that of marking a home-made scale. Here the function of the sprayer being delivery of spray through the nozzle, we are more interested in finding out the rate of spray output through the nozzle and the area of coverage that can be achieved with a full load of sprayer. What is the practical relevance of calibration? When you plan to conduct a pest control operation, you will want to know: The spray volume required to cover the given area How much it would cost you; and the amount of chemical required for the spraying operation. How would you work out the total spray volume? You either should possess a very good experience of spraying, to be able to roughly estimate or else you have to perform a small trial for yourself. One must definitely know the area that can be covered by one full load of spray. Remember that the coverage achieved for one crop (say mustard green) would be different from another crop (say potato) because of the biomass or the density of the foliage; similarly rice crop is different from maize in crop density, plant height and probably biomass. Moreover, it would very much depend at what stage of crop you intend to spray. A maize crop just 5 weeks old would not need the same volume of spray required by a 15-week old maize. The denser the crop, the bigger the amount of spray required. A precise calculation can be made through a small spraying trial with just water spray. Remember, once you know your rate of coverage with, say 5 litres of water, you can workout how much would be required for 1 acre. Such trials that help to find out your rate of spray coverage constitute the spray CALIBRATION. What if we do not calibrate? You will run the risk of buying extra chemical or buying less chemical than is required. Having purchased the chemicals, the prepared spray volume would either be too less or too much. 53 Calibrating a sprayer under different spraying conditions There is standard method of sprayer calibration, however, the procedure requires slight modification under different agricultural situations. They are influenced by topography, planting systems and the type of crops grown. Calibration of a knapsack sprayer can be done in different ways depending upon the following situations: Situation 1: If spraying operation is to be carried out on a flat land where crops are grown in rows with enough inter-row spacings to enable free movement for the operator, then one could follow the standard method of calibration. Situation 2: If spraying operation is to be carried out on a flat or slopy land with crops grown without any well-defined rows (Bhutanese situation) and the operator cannot move freely due to lack of inter-row spacings, then the standard method of calibration needs some modification. Situation 3: If spraying is to be carried out in orchards (apple, orange etc), then calibration has to be done in a completely different manner. Important points to be noted while calibrating: Calibration has to be done by the person who is actually going to carry out the spraying operation and no one else. A constant speed and pressure has to be maintained during the course of calibration and the same has to be maintained when actually operating in the field. A uniform spray coverage has to be maintained (do not overspray on some parts and underspray on others) The results of calibration carried out in one crop should not be used for another as crops have different heights and spread. 54 Things required during calibration: For the standard method: A stop watch or if not available any ordinary watch will serve the purpose. 1. A measuring tape to measure out the area where calibration has to be done. 2. Buckets 3. A jug 4. A graduated cylinder to measure the volume of spray Under Bhutanese field situations: 1. Measuring tape 2. Few wooden pegs 3. 2 Buckets 4. A jug Steps in calibrating a knapsack sprayer - under situation 1 (above) 1. Prepare the sprayer: Rinse and clean sprayer, strainer, nozzle and hose. Fill the sprayer with clean water. Apply pressure with cut-off valve in closed position and check for leaks. Then flush pump, hoses and lance with clean water first without nozzle and next with nozzle replaced on the lance. 2. Determine the nozzle discharge: Fill the sprayer with clean water and pump it up to working pressure. Dip nozzle into a bucket or jar and spray water into the jar for a one-minute period. Shut of the valve exactly at the end of one minute. Measure the quantity of water collected in a graduated cylinder (in litres). This is the nozzle discharge or flow rate expressed in litres per minute Repeat this calibration three times to obtain the average nozzle discharge per minute, which should be used in subsequent calculations. Determine the walking speed of the applicator 3. Determine the walking speed of the applicator Mark the starting point with a stake in a field planted the crop to be sprayed. Spray and walk forward exactly for one minute. When one minute has passed mark the stopping point with another stake and measure the distance between the first and the second stake in metres. Repeat this action 3 times to obtain average walking speed. 4. Establish the width of the spray swath. Spray in the same way as in No.3 above over a very short distance on a dry path or threshing floor. Measure the width of the swath in metres before the spray dries up. 55 5. Calculate area sprayed in one minute Area sprayed per minute (m2/min) = width of swath (metres) x walking speed (metres/min) 6. Calculation of application rate for any given area with the following formula: Nozzle discharge(litres/min) x Area (m2) Volume of spray per area (litres) = ---------------------------------------------------Area sprayed in one minute (m2/min) Calibration of Knapsack sprayer under Bhutanese situation- Situation 2(above) Procedure: 1. Mark a small area in the field where you are going to spray. For example mark with pegs an area of about 10 x 5 m2 in one corner. 2. Measure about 3 to 5 litres of water and fill up the tank. If you do not have any measuring devise, use an empty jug and count in terms of the number of jugs. 3. Spray the marked area with plain water. Make sure that you spray uniformly and avoid spraying until runoff takes place. 4. After having sprayed the area, pour out the remaining water from the tank and measure the volume left over. 5. Calculate the amount of water used up in spraying the marked area. 6. Measure the area of the field that you are going to spray. 7. The total spray volume required to prepare is calculated as: Let A= Total area of the main field to be sprayed (No.6) B = Vol. of spray used up in calibration (No. 5) C = Area sprayed with plain water (No.1) Spray vol. required = A xB C Calibration of sprayers for orchard/ tree spraying: Procedure: 1. Measure out 2- 3 litres of water and fill in to the tank (if knap sack sprayer) or keep it in a bucket (if Gator sprayer or rocking sprayer is used) 2. Select one representative tree in the orchard. You may also repeat on 3 such trees and find the average to get precise results. 3. Spray the selected tree/trees and calculate the volume of spray used in for a single tree. 4. Count the total number of trees in the orchard that need spraying. 5. To get the total spray volume required, multiply the total number of trees with the amount of sray volume required per tree. 56 11. MEASURING PESTICIDES Pesticides can only be used effectively, economically and without undue hazard, if the right quantity is used at the right time. The application of the correct amount of pesticide spray to a crop is a problem for Bhutan as most of our farmers are illiterate and different units of measurement are in use in different regions. There is an overall lack of experience in calculating dosages or spray volumes. However, over the years, extension officers and farmers have acquired a certain experience in the application of pesticides. Trial and error has shown what is to be considered a good coverage with a pesticide to achieve control but further guidance and training is needed in the correct application of pesticides. Recommended dosages of approved insecticides, fungicides or herbicides are being provided by the NPPC as ml EC per litre of water; gm WP or SG per litre of water; gm of insecticide dust or granules per acre (approx. 4000 sq. m). To ensure a correct application of the recommended dosage, the following problems need to be addressed: How to measure the quantity of dust or granules to treat a given area? How to measure the quantity of formulated pesticide required to prepare the recommended spray solution? How to determine the quantity of spray solution required to spray a given surface or a number of trees? How much pesticide solution has to be applied on the crop or trees to achieve the desired control? The first two questions refer to a measurement problem. In table 2 the presently used units of measurement to prepare WP-based pesticide solutions are given. Experience has shown that these units of measurement have been widely adopted by the farming community and therefore its use will be continued but modified as and when needed. The “khaini” tin, used to measure the pesticide formulations is shown in figure 3. 57 Table 2. Measurement of pesticide formulations with khaini tin. Pesticide One bottom lid of Khaini tin holds Carbendazim 50 WP 6 grammes Captan 50 WP 9 grammes Copper oxychloride 50 WP 11 grammes Mancozeb 75 WP 10 grammes Application rates for dusts and granules The adherence to the correct rates of application is more difficult because often the fields are small and farmers use units of measurement that differ from the metric system. As guidance, in table 3 the pesticide dust and granule formulations are listed that are presently recommended and their dosages per acre, per thousand sq m’s. and per 100 sq m’s are given: Table 3. Recommended rates of application of pesticide dusts and granules. Approximate Approximate Pesticide Dosage/acre dosage/1000 sq m’s dosage/ 100sq m’s Insecticide Fenvalerate, 4 DP 600-2500 gm 150-450 gm 15-45 gm Malathion, 5 DP 6000-8000 gm 1500-2000 gm 150-200 gm Pyroquilon, 5GR 12000 gm 3000 gm 300 gm Probenazole, 8GR 12000 gm 3000 gm 300 gm 10000-12000 gm 2500-3000 gm 250-300 gm Fungicide Herbicide Butachlor, 5.GR 58 In Table 4 some local units of surface measurement are given for comparison. Table 4: Units of surface measurement used in Bhutan CONVERSION TABLE 1 Wet land Langdo 0.25 Acres 25 Decimals 1 Dry land Langdo 0.33 Acres 33 Decimals 1 Acre 4 Wet land Langdo 1 Acre 3 Dry land Langdo 1 Hectare 10 Wet land Langdo 1 Hectare 7½ Dry land Langdo The amount of formulated pesticide (in ml or gm) that has to be diluted in 1 litre of water to obtain the recommended spraying dosage is given in table 5 Table 5 Recommended spray solutions for EC’s and WP’s. SPRAY SPRAY SOLUTION SOLUTION PESTICIDE PESTICIDE (DOSAGE) (DOSAGE) Insecticide/acaricide Herbicide Chlorpyrifos 20 EC 4.0 ml / litre of water Glyphosate 41EC Cypermethrin 10 EC 0.5ml / litre of water Metribuzin 70 WP 1.0 gm / litre of water 4.0 ml / litre of water Pendimethalin 30 3.5-5.0 ml / litre of EC water 1.0 ml / litre of water Oxyfluorfen 23.5 2.0 ml / litre of water EC 2.0 ml / litre of water Non- toxic compounds 2.0 ml / 1gm of Linseed Oil copper 2.0 gm /litre of water Protein hydrolysate 5.0 gm / litre of water Dicofol 18.5 EC Dimethoate 30 EC Malathion 50 EC Fungicide (General) Captan 50 WP 2.5 ml / litre of water Carbendazim 50 WP 0.5 gm / litre of water Sandovit (Sticker) 1.0 ml / litre of water Copper oxychloride 50 0.5 gm / litre of water TSO (Tree Spray 30.0 ml / litre of water WP 1.0-2.0 ml / litre of Oil) Hexaconazole 5 EC water Tridemorph 80 EC 0.5 gm / litre of water Fungicide (Rice blast) Blastidicin 1EC 1.0 ml / litre of water Edifenphos 50 EC 2.0 ml / litre of water Isoprothiolane 40 WP 1.0 gm / litre of water Kasugamycin 71.2 WP 1.0 ml / litre of water Tricyclazole 75WP 1.0 gm / litre of water Application rate The present practice in Bhutan is to spray a crop or a tree till just before “run-off” (spraying stops just before the spraying solution starts to drop from the leaves). Since there is much experience with this approach, it should be continued when applying pesticides with a contact action only. When applying pesticides with a systemic action, the coverage does not have to be that thorough because the pesticide is taken up by the plant and transported with the sap stream. For spraying fruit trees, the volume of spray mixture needed cannot be calculated in terms of per acre or sq. m. The uniformity of the spray coverage will depend on the output of the spraying apparatus (litres of spray per minute; size of the droplets), the foliage of the trees etc. To decide how much spray mixture or pesticide formulation needs to be used, the following procedure should be followed: 1 2 3 4 5 6 Fill the spray tank with water, not the chemical. Spray 10 trees of varying sizes. Note the time taken to spray 10 trees. Measure the volume of water used to spray 10 trees. The volume of spray mixture needed to cover 10 trees will be the same as the volume of water used. Assume that it is 50 litres. Count the number of trees per acre (or the number of trees of the orchard). Assume that 100 trees are counted. If 50 litres were used for 10 trees, then the volume needed for 100 trees is: 50 X 100 divided by 10 = 500 litres. Assume that the 100 trees have to be sprayed with Hexaconazole 5 EC at a dosage of 2 ml of formulated product per litre of water, then the quantity of Hexaconazole formulation needed is 500 X 2ml = 1,000 ml (1 litre) 60 12. CALCULATIONS OF PESTICIDE The earlier given rates of application for dusts, granules and pesticide solutions have been calculated by the NPPC to facilitate the correct use of pesticides in the rural areas. Labels on commercially available pesticides also provide general recommendations on dosages and application rates to be used to control pests and diseases. These can be given in different ways. Often the quantity of a formulated product is given that has to be diluted in a given quantity of water to be used on a certain surface. This is very similar to the recommendations given by the NPPC. Pesticides dosages and application rates can also be given as the amount of active ingredient or percentage spray concentration that has to be applied on a given surface in a given amount of water. Based on the active ingredient of the pesticide formulation, calculating the quantity of pesticide formulation that has to be used, is possible. When calculating doses and rates of application, Remember: Area: 1 hectare (ha) 1 acre (0.4 ha) Volume: 1 litre Weight: 1 kilogram (kg) = = = = 10,000 square metres (m2) 4,000 square metres (m2) (approximately) 1,000 millilitres (ml) or 1,000 cubic centimetres (cm3) 1, 000 grams (g) To make the necessary calculations, the following information needs to be available. The recommended rate in kg or litres of active ingredient per ha or per cent spray concentration to be applied, The amount of spray liquid required per ha when applying sprays, The percent active ingredient of the pesticide in the commercial formulation, The area in ha, to be treated. Example 1 - The recommendation (on the label or in the leaflet) for a given foliar spray is to use a 0.04 % solution at a rate of 320 litres of spray liquid per ha. The EC formulation contains 45% active ingredient. The area to be treated is 0.5 ha. Step 1: Calculate how many litres of the EC formulation are required to treat 0.5 ha. First compute the total spray volume in litres needed to treat the area: This is 320 litres/ha x 0.5 ha=160 litres Step 2: Calculate the amount of EC formulation that has to be mixed with the 160 litres of water. This is: Amount of spray required x Recommended spray concentration / percent active ingredient of the EC formulation: Or 160 x 0.04 / 45 =0.142 litre. Step 3: Calculate the amount of EC formulation that has to be added to10 litres of water. This is:10/160 x 0.142 = approx.0.0089 litre (or 9 ml) 61 Example 2 - In a similar way the calculations can be made for a foliar spray based on a wettable powder. The recommendation (on the label or in the leaflet) for a given foliar spray is to use 0.75 kg active ingredient per ha in a volume of spray solution of 320 litres per ha. The WP formulation contains 70% a.i. and the area to be treated is 0.5 ha. Step 1. The total spray volume needed to treat the area is 160 litres of water. (See example 1) Step 2: Calculate how many kg of the WP formulation are required to treat 0.5 ha. First compute the amount in kg of the WP formulation that is required to treat 0.5 ha at the recommended dosage. This is: Recommended rate of application x Area to be treated x100 / Percent of a. i. in the WP formulation. Or: 0.75 x 0.5 x 100 / 70 = 0.536 kg. Step 3. Calculate the amount of WP formulation that has to be added to 10 litres of water. This is:10/160 x 0.536 kg= approx.0.033 kg (or 33 g) Example 3 - To calculate the amount of granules for field application, the following information has to be available. The recommended rate of application in kg a.i.. per ha, The percent of a.i. in the commercial formulation, The area to be treated. In this example is the area to be treated a field of 2 ha and the required rate of application is 0.6 kg a. i. per ha. The granules contain 3 per cent a. i. The quantity of granules required to treat 2 ha is Recommended rate of application in kg a.i per ha x area to be treated x 100 / per cent a.i. in the commercial formulation. Or: 0.6 x2x100 / 3 = 40kg. 62 13. APPLICATION OF PESTICIDES I. CHOICE OF CHEMICALS (INSECTICIDES) Effective control can be obtained by exercising correct choice of a chemical product. To be able to choose the right chemical, one should have a good knowledge about how a chemical acts upon the target pest and affects its life processes. The mode of action of a chemical has to match with the feeding behaviour of the target pest. Brief descriptions of different modes of action of insecticides with general indications of the type of insects controlled are given below to be able to choose the right chemical. However, manufacturers generally produce chemicals with a broad spectrum of action i.e. having a wide variety of action so that one chemical can be used for quite a large number of pests with differing feeding habits. This is an advantage for pest control. a) Stomach poisons: They generally enter a pest’s body through the mouth during feeding (ingestion) and are absorbed through the digestive tract. They are good for leaf eating pest such as caterpillars, flea beetles, grasshoppers etc. A stomach poison has a major advantage over a contact poison because it is addressed only to a pest consuming the leaves, and predators can move safely over the deposit. However, stomach poisons are also rather persistent, and therefore there is risk of ingestion by human beings. b) Contact poisons: These generally penetrate a pest’s body as a result of contact with the legs or other external portions when moving on the treated surfaces such as sprayed leaves. Their action can be short-lived (hours or days) or long-lived (persistent). Mobile insects such as caterpillars or flies are vulnerable to contact poisons, but immobile sucking pests like aphids and scale insects are better controlled by systemic chemicals. c) Systemic poisons: They are characterised by high water solubility, by which property they can be readily taken inside the plant through its roots, stems or leaves. Once inside the plant, systemics move through the plant’s vascular system to other untreated parts from where insects acquire the translocated insecticide during feeding. Except for the way it works through the plant system, it acts upon like a stomach poison. This group of insecticides are effective against sucking pests, borers, leaf miners and nematodes. While using this group of chemicals enough care must be taken and as far as possible, it should be avoided on vegetable crops. Dimethoate is a systemic insecticide. d) Fumigants: These are volatile and enter a pest’s body through the respiratory system and kill at lethal concentration. Moths and butterflies feed very little and even if they do, they generally live on the nectar. So a chemical poison with a contact or a stomach action will have no desired effect. In such a case, fumigation could be the best alternative. But it should be realised that fumigation is possible only in an enclosed area, e.g. in a closed chamber or in a go-down of stored grains under a tarpaulin cover. Fumigants are more commonly used against storage pests. 63 e) Suffocating materials: These are usually oils that clog the respiratory mechanism of pests. Since it is likely to cause damage to leaves, their use has to be during the winter when trees shed their leaves. The Tree Spray Oil (TSO) is one product available through NPPC and is used against over-wintering woolly aphids, San Jose scales, Red spider mites etc. Timing of pesticide application Timing is as essential as the right choice of chemical or the correct method of application. Why? The susceptibility or the vulnerability of our target pests depends on the following factors: 1. Stage of development of pests This means that our chemical sprays will not be equally effective all the time. During periods of rest or reduced biological activity of pests, for instance, as seed or spores, or as eggs, cysts and pupae, they are much more difficult to control than during periods of vigorous growth and voracious feeding. Generally, to kill insect eggs, one needs insecticides with a strong penetrating action (ovicides). The young larval or nymphal stages are normally times of almost continuous feeding and thus of extensive exposure to stomach and contact poisons. The fifth instar is the last instar before pupation and has, therefore, a reduced feeding behaviour. This is why it is often difficult to kill insects at this stage. Adult stages, such as the moths and butterflies cannot be controlled with chemical sprays. This is because of their different nature of feeding. As can be seen from the above description, insects during the larval and nymphal stage eat voraciously as compared to other stages. For some insects the young larva (first instar) feed on the plant surface only for short duration before it bores or mines into the interior parts. A good example is the Brinjal Fruit and Shoot borer (Leucinodes orbonalis). The larva feeds on the surface for a limited time and soon bores into the shoot or into the flower buds and fruits without living behind any trace of entry. Since the size of the larva is small, its entry point can hardly be noticed. When it feeds inside the young shoot, it causes the tip of the shoot to wilt but the symptom on fruits are not noticed until the larva comes out either for pupation or to move on to the next fruit by which time the damage is already done. If a pest such as this has to be controlled, timing of pesticide application is very critical. As soon as we see the first few symptoms, a protective spray might be necessary so that the young larva is killed right at the time of its surface feeding. A similar strategy needs to be adopted for most of the borers: cabbage borer (Mamestra brassicae), citrus leaf miner (Phyllocnistis citrella), Tomato fruit borer (Heliothis armigera Syn. Helicoverpa armigera), rice stem borer (Chilo partellus incertulas, Scirpophaga incertulas), apple fruit borer (Argyresthia sp.) 2. The growth stage of the crop The susceptibility of crop plants to damage from insects, nematodes, diseases, weeds etc., usually varies in the course of their growth period. Seedlings in particular are easy victims for soil pathogens and soil insects. Often, organisms are specific concerning the stage of 64 growth and the parts of the plants they attack. For example: the rice bug (also called Gandhi bug), Leptocorisa acuta damages the developing grains at “milky stage”. The symptoms of loose smut (Ustilago tritici) of wheat appear at the ripening stage of the ears, but the spores are carried over by the seed and germinate in the seedlings. The rice bug may be controlled by spraying the ripening panicles but smut is controlled by seed treatment with fungicides. 3. The development stage of natural enemies and activity of honey bees The stage of development and the whereabouts of natural enemies should be taken into consideration. If the natural enemy population is appreciably high, chances should be given for the natural enemy to control the pest. This can be done either by avoiding the spray or reducing the number of sprays to the bare minimum. Indiscriminate spraying in the past has decimated (killed) predatory and parasites to such an extent that pests of hitherto little economic importance suddenly could become a major cause of damage. These so-called secondary pests usually cease to be a problem if proper attention is given to protecting self-regulating forces in nature. The numerous spiders in rice are, for instance, indispensable agents for controlling plant hoppers and leafhoppers. Spraying of extensive areas would diminish their chances for rapid decolonisation in treated fields; therefore, such spraying should be avoided. There are insects, which are helpful in the pollination. Honeybees are the most common insects that are not only beneficial as pollinating agents but also as producers of honey. Therefore spraying of insecticides must be avoided during the blossoming time when these insects are active in the field. There are chemicals that are supposed to be safe to honey bees but one should be sure of such properties before deciding to spray. 4. The severity of damage or infestation Use of pesticide involves costs and has associated risks to human health. The total cost must be compared with the expected benefits of higher yield or prevention of damage and loss. The Economic Threshold Level (ETL) or Action Threshold Level is an economic standard that indicates the level of infestation when a farmer should start applying pesticides. This means that the level of infestation by pest organisms has been reached when the damage they are causing would surpass the capacity of the crop to tolerate and compensate for it, and the marketing prices would justify the expenditure on crop protection measures. It is basically an IPM tool that enables a farmer to making decisions on spraying. Action thresholds need to be established separately for control of weeds, diseases, insects or other organisms in important crops. Such standards are quite different for high value crops such as vegetables, flowers and fruits. Thus, it is a complicated affair in which plant protection services need to advise farmers. This is further complicated by consumer habits. Since consumers demand fruits and vegetables without any blemishes, fruit and vegetable growers are often enticed to spray frequently and right up to the time of harvest, thereby protecting more the cosmetic appearance of the produce than its nutritional value. While the threshold standards for rice seems to be a well-established scientific tool in some rice growing countries of South East Asia such as Indonesia, its use in Bhutan is not 65 in practice. One reason is: in Bhutan most of the rice, aside the southern belt is grown in a warm temperate region where pest problems as such are not serious enough to warrant any spraying. Except for some sporadic sprays against rice blast since 1995, it can be said with confidence that rice grown in the northern valleys of Bhutan is free from pests. Therefore there does not arise the need to establish any ETL. However, lack of established ETLs in Bhutan cannot be an excuse for not spraying. Especially on important cash crops such as apples, potato and vegetables in general, sprays might be required to not only prevent the yield loss but also to ensure quality produce in terms of physical appearance. While the time for spraying might depend on the type of crop and the pest, the assessment of the severity of damage or infestation has to be more rationale and based on practical realities. A rough estimation of the cost of spraying must be made to find out the cost-benefit ratio. A ngultrum spent on control should bring in a benefit of more than a ngultrum. Otherwise the control measure is not justified. Therefore the time for spraying should be dictated by the level of infestation or the severity of damage. In other words: Spray only as and when necessary! 5. The type of weather and the time of day Adverse weather conditions may spoil the result of a technically good application. A heavy rain shortly after the spraying may wash off the chemical before it can have its effect. For this reason, it is recommended that insecticides not be sprayed when rain is expected within the same day. In the case of herbicide application on the soil, however, rainfall shortly after spraying may improve the penetration of the weed killer into the soil and into the rooting zone of the weeds. Spraying on a windy day may cause spray drifts. Spraying during the hottest hours of the day with bright sunshine should be avoided generally, for several reasons: evaporation of the volatile components in the spray liquid is higher; rapid evaporation of the spray droplets may increase the risk of phytotoxic scorching; working under the host sun leads to heavy perspiration and is fatiguing; both factors increasing the risk of intoxication of the people involved in the application. Therefore it is recommended that pesticide applications be carried out in the early morning or late afternoon, or on days when the sky is overcast. One should also take into account the behaviour of the insects to be controlled. To control a typical daytime feeder such as rice hispa (Dicladispa armigera), it is better to spray in the morning hours. But to control the rice armyworms, or ear-cutting caterpillars, (Mythimna spp.) which feed during evening and night, the late afternoon would be the best time for spraying. Spraying or fumigation in store, glasshouses or plastic tunnel constructions should be planned at the end of a working day when nobody needs to enter the treated area for some period of time. 66 Good knowledge of the properties of the pesticide used, of the behaviour of the pests to be controlled and of the characteristics of the application equipment are necessary for proper timing of the application in relation to weather and time of day. 6. Pre-harvest interval For most of the chemicals applied on vegetable crops like cabbage, cauliflower and broccoli, the recommended waiting period or the pre-harvest interval is two weeks. This means that a minimum of two weeks must pass after the crop has received the last spraying. After two weeks it is considered safe to harvest and consume. For maintaining the cosmetic value rather than the nutritional value, horticulture produce (especially vegetables) coming to Bhutanese weekend markets from Falakata in India are known to be heavily sprayed just a couple of days before it is harvested and brought to Bhutan. Unless proper measures are taken, Bhutanese urban dwellers are likely to suffer from residual effects that may lead to health problems of unknown cause in the long run. This is likely to happen due to cumulative accumulation of the toxicants, the effect of which is known as chronic poisoning. There are two types of poisoning: a) Acute poisoning b) Chronic poisoning. Acute poisoning is the result of an accidental or intentional single or repeated exposure to a substantial dose of toxicant. In case of acute poisoning, the effect is noticed soon after the exposure. For instance, headache, giddiness, vomiting, paralysis are symptoms of a different degree of poisoning effect. Chronic poisoning is as a result of prolonged or frequently repeated exposure to lower doses of the toxicant. The effect is normally not realised immediately and it is difficult to pinpoint the cause. There are, however, cases of abnormalities developing many years later. Therefore, abundant care must be taken whenever one buys agriculture produce coming from India. Thorough washing is one way of ensuring the removal of any pesticide residues, if there is any. References: Oudejans, J.H. (1991). Agro-pesticides: Properties and functions in integrated crop protection. UNESCO (for Asia and the Pacific). Van Emden, H.F. (1989). Pest Control. Cambridge University Press. 67 14. PESTICIDE PROFILES Blasticidin (Blasticidin-S; BLA-S) Classification: Fungicide. Formulation: 1% a.i. EC. Toxicity and Toxicity Class: LD50:16 mg/kg; I B, Highly Hazardous. Toxicity Class Formulation: II Properties and Use: An antibiotic used as a preventive and curative contact fungicide, temporarily introduced in Bhutan to control rice blast. Cautions: Irritant to the eye. Higher than recommended rates will cause leaf spotting. Slightly toxic to fish. No recommended interval between application and harvest available. No antidote known. Extension Leaflet: No37 (Rice Blast) Butachlor (Golteer, Machete, Punch etc.) Classification: Herbicide. Formulation: 5% a.i. granules. Toxicity and Toxicity Class: LD50:3300mg/kg; Unlikely to present acute hazard in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: A selective pre-plant or pre-emergence herbicide to control annual grasses and certain broad-leaved weeds in rice. It is not effective against Potamogeton distinctus.(“sochum’’) Cautions: Mild skin and eye irritant. Do not treat if rain is expected within 6 hours. Toxic to fish. Extension Leaflet: No35 (Weeds) 68 Carbofuran (Furadan) Classification: Insecticide. Formulation: 3% a.i. granules. Toxicity and Toxicity Class: LD50: 8mg/kg; I B, Highly Hazardous. Toxicity Class Formulation: II Properties and Use: A carbamate compound used as a systemic and contact insecticide/nematicide. Cautions: Toxic to bees, birds and fish. Minimum period between application and harvest is 6 weeks. Use only allowed by Drukseed, because of high toxicity and long interval between application and harvest. Captan (Hexacap, Orthocide, etc.) Classification: Fungicide. Formulation: 50% a.i. WP. Toxicity and Toxicity Class: LD50 :9.000 mg/kg; Unlikely to present acute hazard in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: A protective and curative fungicide for foliage, seed and soil application, effective against a wide range of pathogens. It is used as a spray to control leaf spots and fruit rots of cucurbits, peppers and potatoes. The product can also be used as seed dressing or as a soil drench to control damping-off. Cautions: May be irritating to skin, eyes, nose and mouth. Toxic to fish. Do not use treated seed for human or animal feed. Minimum period of two weeks between application and harvest. Extension Leaflet No 6 (Apple Scab) Carbendazim (Derosal, Bavistin, etc.) Classification: Fungicide. Formulation: 50% a.i. WP. Toxicity and Toxicity Class: LD50:10.000 mg/kg.; Unlikely to present acute hazard in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: A systemic protective and curative fungicide controlling many fungal diseases of crops. Cautions: Toxic to fish. Phycomycetes fungi are not controlled. Harmless to bees. Minimum period of two weeks between application and harvest Extension Leaflet No 6 (Apple Scab); No 30 (Apple Blotch) 69 Chlorpyrifos (Dursban, Lorsban, Durmate, etc.) Classification: Organophosphorous insecticide. Formulation: 20% a.i. EC. Toxicity and Toxicity Class: LD50:136 mg/kg ; II, Moderately Hazardous. Toxicity Class Formulation: II Properties and Use: This insecticide is primarily effective by contact action and as a stomach poison. The persistence on leaves is rather short but it may remain effective in the soil for several weeks. It is widely used against a large array of insect pest and their larvae. Cautions: Prevent skin contact with the concentrated and formulated insecticide. Avoid inhalation of spray. No systemic action. Toxic to birds, fish and aquatic invertebrates. Minimum period of two weeks between application and harvesting. Antidote: Atropine. Extension Leaflet: No 2 (Woolly Aphid), No 3 (Leaf Beetles), No 7 (Apple Fruit Borer), No 11 (Two Spotted Apple Beetle), No 12 (Green Apple Weevil), No 15 (Ants), No 18 (Flat Spiny Caterpillar), No 20 (Cutworms), No 22 (Apple Fruit Beetles), No 24 (Cabbage Aphid), No 25 (White Shield Bug), No 33 (Potato Tuber Moth), No 34 (Vine Weevil) Copper oxychloride (Cupravit, Fytolan, Cuprastar etc.) Classification: Copper fungicide. Formulation: 50% a.i.WP. Toxicity and Toxicity Class: LD50: 1440mg/kg; III, Slightly Hazardous. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: An inorganic copper compound used as a foliage fungicide to prevent or to control foliar diseases including potato blights, die-back etc. Cautions: Corrosive to iron. Thorough coverage necessary for good results. Avoid excessive skin contact with concentrate. Toxic to fish. Minimum period of three weeks between application and harvesting. Extension Leaflet No 4 (Chilli Blight) Cypermethrin (Ripcord, Cymbush, Sherpa, etc.) Classification: Pyrethroid insecticide. Formulation:10 % a.i. EC. Toxicity and Toxicity Class: LD50: 250 mg/kg; II, Moderately Hazardous. Toxicity Class Formulation: III Properties and Use: A broad-spectrum insecticide with a high contact and non-systemic stomach action and a fast knockdown activity. Effective against a wide range of insect pests, particularly leaf and fruit eating caterpillars, sucking pests and beetles in fruit, vegetables and other crops. Cautions: Avoid contact of the concentrate with the skin. Good spray coverage is essential, since it has no systemic activity. 70 - Do not inhale spray mist. Very toxic to fish. Moderately toxic to bees. Toxic to some predators. Minimum period of 10 to 14 days between application and harvest. Extension Leaflets: No 2 (Woolly Aphid), No3 (Leaf Beetles), No 11 (Two-spotted Apple Beetle), No12 (Green Apple Weevil), No 18 (Flat Spiny Apple Weevil), No 21 (Harlequin Bug), No 22 (Apple Fruit Rollers), No 23 (Cabbage Butterfly), No 24 (Cabbage Aphid), No 25 (Wheat Shield Bug), No 33 (Potato Tuber Moth) Deltamethrin (Decis, K-Othrin, Calypso, etc.) Classification: Pyrethroid insecticide. Formulation: 2.8 a.i.% EC. Toxicity and Toxicity Class: LD50: 135g/kg.; II, Moderately Hazardous. Toxicity Class Formulation: Unlikely to produce acute hazard in normal use. Properties and Use: A broad-spectrum insecticide used as a contact and stomach-poison providing control for up to three weeks. It has a rapid knock-down action. Cautions: Avoid direct contact of the concentrate with the skin. Do not inhale spray mist Good spray coverage is essential, since it has no systemic activity.. Very toxic to fish and aquatic life, bees and natural enemies. Minimum period of one week between application and harvest. Extension Leaflet: No 28 (Cabbage White Butterfly) Dicofol (Kelthane, Colonel-S) Classification: Acaricide. Formulation: 18.5% a i. EC. Toxicity and Toxicity Class: LD50: 690 mg/kg; III, Slightly Hazardous. Toxicity Class Formulation: Unlikely to produce acute hazard in normal use. Properties: An acaricide effective against a wide range of mite pests without harmful effects on insect predators and bees. It has a rapid killing action and a long residual effect. Cautions: Avoid skin contact with the concentrate. Do not inhale spray drift. Toxic to fish. Safe for bees. Minimum period of 7 days between application and harvest Extension Leaflet: No 14 (Fruit Tree Red Spider) Dimethoate (Rogor, Perfektion, Hexagor, etc.) Classification: Organophophorous insecticide. Formulation: 30% a i. EC Toxicity And Toxicity Class: LD50:150mg/kg; II, Moderately Hazardous. Toxicity Class Formulation: II 71 Properties and Use: A systemic and contact insecticide/acaricide with a broad spectrum of activity,applied against sucking and leaf eating insect pests and against mites. Cautions: Avoid skin contact with the concentrate. Avoid inhalation of spray mist. Toxic to bees. Toxic to fish. A minimum period of 15 days between application and harvest. Extension Leaflet: No 26 (Citrus Leaf Miner) Edifenphos (Hinosan) Classification: Fungicide. Formulation: 50 % a.i. EC. Toxicity and Toxicity Class: LD50:150 mg/kg; I B, Highly Hazardous. Toxicity Class Formulation: II Properties and Use: A non-systemic protective and curative fungicide for the control of rice blast. Cautions: A very toxic fungicide. All safety recommendations should be strictly followed. Toxic to fish. No recommended period between application and harvest available. Extension Leaflet: No 37( Rice Blast) Fenvalerate (Sumicidin) Classification: Pyrethroid insecticide Formulation: 4% a i. DP. Toxicity and Toxicity Class: LD50: 450mg/kg; II, Moderately Hazardous. Toxicity Class Formulation: III Properties and Use: A broad- spectrum insecticide acting by contact or as a stomach poison. It has a rapid knock-down effect. Cautions: Avoid skin contact with the concentrate. Avoid inhaling spray mist. Good spray coverage essential, since it has no systemic activity. Very toxic to fish and bees. Some toxicity to birds. Minimum interval of at least two weeks between application and harvest. Extension Leaflets: No 19 (Bollworm), No 33 (Potato Tuber Moth) Glyphosate (Roundup, Accord, etc.) Classification: Herbicide. Formulation: 41% a.i. EC. Toxicity and Toxicity Class: LD50: 4230 mg/kg; Unlikely to present acute hazard in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. 72 Properties and Use: A post-emergence broad-spectrum systemic herbicide controlling most perennial and annual weeds. Cautions: May cause eye and skin irritation. Initial action is rather slow. Extension Leaflet: In preparation. Hexaconazole (Anvil) Classification: Fungicide. Formulation: 5% a.i. SC. Toxicity and Toxicity Class: LD50: 2180mg/kg; Unlikely to cause acute hazard in normal use. Toxicity Class Formulation: Unlikely to cause acute hazard in normal use. Properties and Use: A broad-spectrum systemic fungicide with preventative and curative action. Cautions: May cause eye irritation. Minimum period of two weeks between application and treatment. Extension Leaflets: No 28 (Himalayan Apple Rust) Isoprothiolane (Fuji-one, Fudiolane) Classification: Fungicide. Formulation: 40% a.i. WP. Toxicity and Toxicity Class: LD50:1190 mg/kg; III, Slightly Hazardous. Toxicity Class Formulation: Unlikely to produce acute hazard in normal use. Properties and Use: A systemic fungicide, translocated through both the leaves and the roots. It can be used as a protective and as a curative fungicide. It has been introduced temporary in Bhutan to control rice blast. Cautions: No recommended interval between application and harvesting available. Extension Leaflet: No 37(Rice Blast) Kasugamycin (Kasumin, KSM) Classification: Fungicide. Formulation: 71.2 % a.i.WP. Toxicity and Toxicity Class: LD5010.000 mg/kg; Unlikely to present acute toxicity in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. 73 Properties and Use: An antibiotic compound with preventive and curative properties that is used as a foliar systemic fungicide/bactericide. Temporary in use in Bhutan to control rice blast. Cautions: A very safe fungicide. Somewhat toxic to bees. No recommended interval between harvest and application available. Extension Leaflet: No 37(Rice Blast). Malathion (Cythion, Celthion, Malathion, etc.) Classification: Insecticide. Formulation: 5 % a.i. .DP; 50% a.i..EC. Toxicity and Toxicity Class: LD50 :2100 mg/kg; III, Slightly hazardous. Toxicity Class Formulations: Unlikely to present acute hazard in normal use. Properties and Use: A broad-spectrum insecticide with a rather low persistence and acting as a contact and stomach poison. It is used to control a large array of insect pests of agricultural, horticultural, veterinary and public health importance. Cautions: Avoid use of old stocks. Toxic to bees. Toxic to fish. Minimum period of 7 days between application and harvest. Extension Leaflets: No 1 (Chinese Citrus Fly); No 19 (Bollworm) Mancozeb (Dithane M-5, Manzanate D, Manzeb) Classification: Fungicide. Formulations: 75% a, i. WP. Toxicity and Toxicity Class: LD50 > 8000mg/kg; Unlikely to present acute hazard in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: A broad-spectrum fungicide with protective and curative action, used to control a large array of foliar diseases It is also used for seed treatment. Cautions: May irritate skin, eyes and nose. A good spray coverage is essential. Toxic to fish. Minimum period of one week between application and harvest. Extension Leaflets: No 6 (Apple Scab), No 15 (Small suckers and Sooty Mould), No 30 (Apple Blotch) Metribuzin (Sencor, Lexone, Contrast, etc.) Classification: Herbicide. Formulation: 70% a.i. WP. Toxicity and Toxicity Class: LD50: 2200mg/kg; Unlikely to present acute hazard in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: A selective pre and post-emergence herbicide to control weeds in selected crops. 74 Cautions: - Certain crops (crucifers, cucumbers and strawberries) are sensitive to the herbicide. Do not plant sensitive crops for four months. Extension Leaflet: In preparation. Oxyfluorfen (Koltar, Goal) Classification: Herbicide. Formulation: 23.5% a. i. EC. Toxicity and Toxicity Class: LD50:5000mg/kg.; Unlikely to present acute hazard in normal use. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: A selective pre- and post-emergence herbicide to control weeds in orchards. Cautions: Toxic to fish. Do not graze treated area. More effective on broadleaves than on grasses. Extension Leaflet: In preparation. Pendimethalin ( Stomp, Gogosan) Classification: Herbicide. Formulation: 30% a.i. EC. Toxicity and Toxicity Class: LD50:1250 mg/kg; III, Slightly Hazardous. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties and Use: A pre-plant and pre-emergence herbicide to control weeds in rice and orchards. Cautions: More effective on grasses than on broad-leaved weeds. Toxic to fish. Do not store below 5’C. Extension Leaflet: In preparation. Probenazole ( Oryzemate) Classification: Fungicide. Formulation: 8% a.i. GR. Toxicity and Toxicity Class: LD 50: 2030mg/kg; Unlikely to present acute hazard in normal use. Toxicity class formulation: Unlikely to present acute hazard in normal use. Properties and Use: A systemic fungicide/bactericide that is temporally introduced in Bhutan to control rice blast. It should be applied 7 to 10 days before rice a blast outbreak. The fungicide is taken up by the roots and moved upwards in the plant. Protection should last for over a month Cautions: Paddy water should remain still for 4-5 days after application to achieve results. Toxic to fish. No recommended interval between application and harvest available. 75 Extension Leaflet: No 37 (Rice Blast) Pyroquilon (Coratop, Fongoren) Classification: Fungicide. Formulation: 5% a.i. granules. Toxicity and Toxicity Class: LD50: 320mg/kg; II, Moderately Hazardous. Toxicity Class Formulation: Unlikely to present acute hazard in normal use. Properties. A systemic protective fungicide with a long action temporally used in Bhutan to control rice blast. Cautions: May cause eye and skin irritation. No recommended interval between application and harvest available. Extension Leaflet: No 37(Rice Blast) Tricyclazole ( Bearn, Bim, Blascide) Classification: Fungicide. Formulation: 75% a.i.WP. Toxicity and Toxicity Class: LD50: 305mg/kg; II, Moderately Hazardous. Toxicity Class Formulation: II Properties and Use: A systemic fungicide that is also taken up by the root system. It is temporally used in Bhutan to control rice blast. It can be applied as a foliar spray, flat drench on the soil or as seed treatment. Cautions: Not so suitable for transplanted rice. No recommended interval between harvest and application available. Extension Leaflet: No 37(Rice Blast) 76 Tridemorph (Calixin,etc.) Classification: Fungicide. Formulation: 80% EC. Toxicity and Toxicity Class: LD50:650 mg/kg; II, Moderately Hazardous. Toxicity Class Formulation: III Properties: A systemic fungicide with a preventive and curative action that is absorbed by foliage and roots to control powdery mildew in citrus and apples. Cautions: May cause skin and eye irritation. No recommended interval between application and harvest available. Extension Leaflet: In preparation. Zincphosphide Classification: Acute rodenticide. Formulation: 80-90% concentrates Toxicity and Toxicity Class: LD50: 45mg/kg; I B, Highly Hazardous. Toxicity Class Formulation: N. A. Properties and Use: It is an acute or single dose poison, used in baits to control rats and mice. Cautions: The concentrate and prepared baits are very toxic. Strictly follow instructions given in Extension Leaflet. Extension Leaflet: In preparation. 77