INSECTICIDE ROW TREATMENTS FOR THE CONTROL OF WIREWORMS IN POTATOES

In field plots, where about 20 per cent of the potato tubers were damaged by wireworms in untreated plots, not more than 5 per cent were damaged after band treatments with aldrin or heptachlor dusts, granules, or impregnated fertilizers, applied at 1 or 3 lb. of toxicant per acre during planting. At least 15 per cent of the tubers were damaged after band treatments with chlordane dust at the same rates. Damage after treatments with aldrin or heptachlor dusts applied in the open furrow by hand immediately before planting was similar to that after band treatments at the same rates. Where about 40 per cent of the tubers were damaged in untreated plots, 9 and 15 per cent of the tubers were damaged after band treatments with granular aldrin and heptachlor respectively, each at 3 lb. per acre; 23 and 28 per cent of the tubers were damaged after band treatments with the same insecticides at 1 lb. per acre. Thus, the treatments reduced damage enough to bring the potato crop to top table stock grade, without culling, only where potential damage was light. None of the treatments reduced wireworm numbers more than 75 per cent. None of the treatments increased the yield of tubers. Furrow treatments with aldrin and heptachlor dusts reduced yield in one of two tests, presumably because of phytotoxicity.