Interactions of Herbicides with Insecticides in Soybeans (Glycine max)

Field and greenhouse experiments in 1981 and 1982 determined the potential interactions of three preemergence and three postemergence herbicides with four granular insecticides in soybeans [ Glycine max (L.) Merr.]. Generally, metribuzin [4-amino-6- tert -butyl-3-(methylthio)- as -triazin-5(4 H )-one] increased soybean injury and lowered yields when applied to plots treated with an organophosphate insecticide at planting. Soybean injury from these treatments and from aldicarb [2-methyl-2-(methylthio)-propionaldehyde- o -(methylcarbamoyl)oxime] plus metribuzin applied in the field was greater in 1982 than 1981 due to excessive rainfall immediately after planting. Oryzalin (3,5-dinitro- N 4 , N 4 -dipropylsulfanilamide) plus several of the in-furrow insecticide treatments in the greenhouse increased injury to soybeans. Other than this, the method of insecticide application, banded or in-furrow, had no effect on that caused by each pesticide combination.