Interactions of Insecticide–Nematicides, Metribuzin, and Environment on Soybean Injury and Yield

Abstract

Seven insecticide-nematicides were tested in different formulations, rates, and methods of application with metribuzin for their interactive effect on soybean. Under low temperature and high rainfall conditions, two formulations of carbofuran applied at 2.2 kg (AI)/ha in-furrow without metribuzin were more phytotoxic than other insecticide-nematicides. Significant soybean injury resulted when metribuzin was applied alone at 0.6 kg (AI)/ha, but combinations of the insecticide-nematicides and metribuzin produced even greater injury. Yields were not affected when insecticide-nematicide treatments were used alone. Yield reductions resulted from applications of metribuzin or combination treatments (except fenamiphos in-furrow), and yields from most combination treatments were significantly lower than comparable insecticide-nematicide treatments used alone. Under more favorable growing conditions (higher temperature), plant height increases, soybean injury, and yield reductions were observed depending on pesticide type or combination, rate, or method of application.