Despite a history of several decades of pesticide regulation, continuous innovation, and considerable practical experience with using pesticides in agriculture, the environmental impact of pesticide use continues to be of serious concern. Subscribe now to be the first to hear about specials and upcoming releases. Title Author. Pesticides: Problems, Improvements, Alternatives. Description of this Book Despite a history of several decades of pesticide regulation, continuous innovation, and considerable practical experience with using pesticides in agriculture, the environmental impact of pesticide use continues to be of serious concern.
This preview is indicative only. Since applicators have no control over formulation adjuvants, this publication focuses on spray adjuvants. Adjuvants are designed to perform specific functions, including buffering, dispersing, emulsifying, spreading, sticking, and wetting. Adjuvants also can reduce evaporation, foaming, spray drift, and volatilization. No single adjuvant can perform all these functions, but different compatible adjuvants often can be combined to perform multiple functions at the same time.
Therefore, using adjuvants may not only help minimize spray application problems but also boost the pesticide's effectiveness. The spray adjuvants can be categorized into two groups: activator adjuvants and special-purpose or utility adjuvants. The main purpose of activator adjuvants is to improve the "activity" of the pesticide product. These improvements--both physical and chemical--generally lead to better absorption and, as a result, a more efficient use of the pesticide.
Activator adjuvants include surfactants, oils, and nitrogen-based fertilizers. Figure 1.
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Droplet spread on waxy leaf surface due to surfactant. Surfactants surface acting agents , also called wetting agents and spreaders, physically change the surface tension of a spray droplet. For a pesticide to perform its function properly on a plant, the spray droplet must be able to wet the foliage and spread out evenly.
Surfactants make the area of pesticide coverage larger, which increases the pest's exposure to the chemical see Figure 1.
Pesticides, Problems, Improvements, Alternatives. — Vrije Universiteit Amsterdam
Surfactants are particularly useful when applying a pesticide to a plant with waxy or hairy leaves. Without proper wetting and spreading, spray droplets often run off or fail to provide good coverage to the surfaces. Too much surfactant, however, can cause excessive runoff, which may make the pesticide less effective. Surfactants are classified by the way they ionize, or split apart, into electronically charged molecules called ions. Use only the type as directed on the label. Organo-silicone Surfactants a newer group taking the place of nonionic surfactants.
Keep in mind that selecting the wrong surfactant can reduce the effectiveness of a pesticide product and increase the risk of plant injury. Oils are being used to control grassy weeds. The three types of oil-based adjuvants include crop oils, crop oil concentrates, and vegetable oil concentrates. Crop oils promote the penetration of a pesticide spray either through a plant's waxy cuticle or through an insect's tough, chitinous shell.
Traditional crop oils are more commonly used for insect and disease control and rarely with herbicides. Crop oil concentrates COCs are made up of 80 to 85 percent emulsifiable petroleum-based oil and 15 to 20 percent nonionic surfactant.
Crop oil concentrates have the penetration properties of oil and the spreading properties of a surfactant. COCs are often used with postemergence herbicides. Vegetable oil concentrates VOCs are made up of 80 to 85 percent crop derived seed oil usually cotton, linseed, soybean, or sunflower oil and 15 to 20 percent nonionic surfactant. To improve their performance, many VOCs have undergone a process called esterification, which increases the oil-loving characteristics of the seed oil and results in a methylated seed oil MSO.
MSOs work the same as traditional crop oil concentrates to increase penetration of the pesticide into the target pest.
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Improved herbicide activity has been shown by adding ammonium sulfate or urea-ammonium nitrate to the spray mixture. Nitrogen fertilizers may replace some adjuvants but are usually included in addition to a surfactant and a crop oil concentrate for use with systemic pesticide products. Many fertilizer-based adjuvants are available in liquid forms, which are easier to mix and provide more consistent results. Fertilizers should only be used with herbicides when recommended by the label. Special purpose adjuvants fix specific conditions that can affect the spray solution or the actual application of the pesticide in a negative way.
By controlling these factors, you can maximize the efficient use of the pesticide. Compatibility agents, buffering and conditioning agents, defoaming agents, deposition agents stickers , and drift control agents and thickeners modify the physical characteristics of the spray solution. Foam markers, tank cleaners, colorants, and suspension agents help minimize application problems. Carefully follow product label directions before adding any adjuvant to a spray mix.
Pesticides are commonly mixed with liquid fertilizers or other pesticides. However, some combinations can be physically or chemically incompatible, causing clumps and uneven distribution in the spray tank. Occasionally, the incompatible mixture will clog the pump and hoses, resulting in expensive cleanup and repairs. Using a compatibility agent may eliminate these problems. A "jar test" can help determine the stability of the mixture. Always wear personal protective equipment PPE when pouring or mixing pesticides, even for this simple test. To conduct a jar test, add proportionate amounts of all the products you intend to mix in the spray tank to a clear quart jar.
When using a liquid fertilizer carrier, many herbicide labels recommend using two jars for this test--one with and one without a compatibility agent.
Step 1. Measure 1 pint of water or carrier solution into a clear quart jar. Use the same water source that will be used in the tank mix. Step 2. Add proportionate amounts of each product, one at a time, in the order suggested on the label, or add ingredients in the following order.
Stir each time a formulation has been added. Step 3. Shake the jar vigorously and allow it to stand for at least 15 minutes. The mixture is probably not compatible if scum forms on the surface, the mixture clumps, or any solids settle to the bottom except for wettable powders.
Do not use a mixture that gives off heat determined by feeling the jar as that indicates a chemical reaction has occurred and changed the chemical properties of the products. You can skip to the end and leave a response. Pinging is currently not allowed. Name required. Mail will not be published required. Donate Join Sign Me Up! Soil microbiome 1.