FUNGICIDES AND INSECTICIDES APPLIED TO PELLETED SUGAR-BEET SEEDS .1. DOSE, DISTRIBUTION, STABILITY AND RELEASE PATTERNS OF ACTIVE INGREDIENTS

Loading of active ingredient between individual pellets varied signifi cantly. The coefficients of variation (CV) for thiram ranged from 25 t o 77% and for hymexazol, methiocarb, furathiocarb and imidacloprid bet ween 12 and 34%. With carbofuran the CV ranged from 14 to 62% dependin g on pelleting process and applied dose. Stability of applied pesticid e after storage depended on pellet type and applied fungicide/insectic ide combination. Decrease of thiram during storage was related to the pellet type, but hymexazol decreased in all pellet types, especially i n combination with furathiocarb, benfuracarb and carbosulfan. Carbofur an, methiocarb, tefluthrin and imidacloprid individually were stable d uring storage. The conversion rate of furathiocarb, benfuracarb and ca rbosulfan 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 var ied 0-75%. Hymexazol decreased quickly in the pellets and after 4 week s no active ingredient could be detected, in most pellet types, even w ith slow release products. Thirteen to 71% of furathiocarb, benfuracar b, carbosulfan, carbofuran and tefluthrin was still present in the pel lets after 8 weeks, depending on pellet type and insecticide/fungicide combination in the pellets.