FUNGICIDES AND INSECTICIDES APPLIED TO PELLETED SUGAR-BEET SEEDS .3. CONTROL OF INSECTS IN SOIL

In field trials where pygmy mangold beetles (Atomaria linearis), sprin gtails (Onychiurus armatus), symphylids (Scutigerella immaculata), mil lipedes (Blaniulus guttulatus and Brachidesmus superus) and wireworms (Agriotes lineatus) were prevalent, improved control was obtained by i ncorporating furathiocarb (at 40-60 g a.i./unit), benfuracarb (at 45-5 0 g a.i./unit), tefluthrin (at 6-12 g a.i./unit) or imidacloprid (at 3 0-90 g a.i./unit) in pelleted sugar-beet seeds. In particular, pygmy m angold beetles were very susceptible to all these insecticides and gen erally very little dose response could be detected; this means that th e quantity of tefluthrin and imidacloprid, but also of furathiocarb an d carbofuran, could be lowered. Immigrating adults of pygmy mangold be etles could be controlled by imidacloprid only. Sometimes under specia l conditions, which favoured a long period of emergence, active ingred ients in pelleted seeds provided less protection against millipedes an d symphylids than carbofuran granules. However carbofuran granules par tially failed too, if the active ingredient was released insufficientl y. Although differences in the quantity of insecticides between pellet ing processes were detected, the protective action of the fungicides a nd insecticides was always sufficient. No significant differences in e fficacy between pelleting processes could be detected.