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Pesticide Use and Calibration
Published in L.B. (Bert) McCarty, Golf Turf Management, 2018
Wettable powders (W or WP). Wettable powders are finely ground solids resembling dusts, and consist of a dry diluent (usually a hydrophilic clay such as bentonite or attapulgite) plus the pesticide and perhaps adjuvants. Usually, pesticides make up 50% to 80% (by weight) of a wettable powder formulation. The various adjuvants in the formulation prevent lumpiness or flocculation of the finely ground materials and improve mixing in the spray tank. Wettable powders do not dissolve in water but rather form unstable suspensions giving a cloudy appearance. Vigorous agitation is required to prevent settling of the suspended particles. Inhalation hazards also exist when pouring and mixing the powder. Wettable powder formulations cause rapid nozzle wear, often clog nozzles and screens, and may leave visible residues.
Production of Microbial Insecticides
Published in Nduka Okafor, Benedict C. Okeke, Modern Industrial Microbiology and Biotechnology, 2017
Nduka Okafor, Benedict C. Okeke
The nature of the surface on which the insecticide is applied and which may be oily, smooth, or waxy may prevent the liquid from wetting the sprayed surface. Spreaders or wetting agents which are surface-tension reducers may be added. Wetting agents may be added to dusts to produce wettable-powders which are more easily suspended in water. Some wetting agents and spreaders which have been used for agricultural Bacillus thuringienses include alkyl phenols Tween 20 and Triton X114, and for viruses, Triton X100 and Arlacel ‘C’ which are all commercial surface-tension reducing agents.
Turning DDT into ‘Didimac’: Making insecticide products and consumers in British farming after 1945
Published in History and Technology, 2022
Identifying the best type of formulation was important as this affected how well the insecticide adhered to, or covered, a plant, Dusts are prepared by combining a quantity of the insecticide with an inert diluent such as talc, clay, pyrophyllite or calcium silicate. A wettable powder is usually made by adding a wetting agent to a dust, which when mixed for use, forms a suspension in water. To make a liquid formulation, an insoluble insecticide must first be dissolved in an organic solvent and then either made up as an emulsion concentrate or as a miscible liquid, both of which form an emulsion when diluted with water for use. The quantity of actual insecticide in the formulation is varied to give concentration products of differing percentage. Formulation therefore allows insecticides to be applied either as dusts or as sprays. It allows very small amounts of actual insecticides being applied to large areas … . The addition of wetters and spreaders helps to give a better cover of the insecticide on the plant. Formulation may also increase the effectiveness, penetration and the persistence of the insecticide. It may also affect its speed of action and sometimes even the species of insect controlled. 67