Fungicides and insecticides applied to pelleted sugar-beet seeds. I. Dose, distribution, stability and release patterns of active ingredients
1995
Huijbregts, A.W.M. | Gijssel, P.D. | Heijbroek, W.
Loading of active ingredient between individual pellets varied significantly. The coefficients of variation (CV) for thiram ranged from 25 to 77% and for hymexazol, methiocarb, furathiocarb and imidacloprid between 12 and 34%. With carbofuran the CV ranged from 14 to 62% depending on pelleting process and applied dose. Stability of applied pesticide after storage depended on pellet type and applied fungicide/insecticide combination. Decrease of thiram during storage was related to the pellet type, but hymexazol decreased in all pellet types, especially in combination with furathiocarb, benfuracarb and carbosulfan. Carbofuran, methiocarb, tefluthrin and imidacloprid individually were stable during storage. The conversion rate of furathiocarb, benfuracarb and carbosulfan to carbofuran during storage was related to the pellet type and was enhanced by the presence of hymexazol. Analysis of the active ingredients in pellets periodically after sowing showed the percentage of the initial thiram concentrations present 4 weeks after sowing varied 0-75%. Hymexazol decreased quickly in the pellets and after 4 weeks no active ingredient could be detected, in most pellet types, even with slow release products. Thirteen to 71% of furathiocarb, benfuracarb, carbosulfan, carbofuran and tefluthrin was still present in the pellets after 8 weeks, depending on pellet type and insecticide/fungicide combination in the pellets.
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