The relationship between Aphis glycines and Soybean mosaic virus incidence in different pest management systems

The soybean aphid, Aphis glycines, causes yield loss and transmits viruses such as Soybean mosaic virus (SMV) in soybean (Glycine max). Field experiments were designed to monitor the landing rate of A. glycines and transmission of SM to soybean grown in six crop management environments. Management systems evaluated were the application of postemergence insecticide or no insecticide, and within each insecticide treatment no herbicide, glyphosate, or imazamox application. In 2001, early-season incidence of SMV was 2%, which increased to 80% within 18 days after the beginning of the A. glycines flight. In 2002, the incidence of SMV was 1% prior to the arrival of A. glycines, and increased to 44% within 21 days. The landing rate of A. glycines was fivefold higher in 2001 than in 2002. The incidence of SMV was lower in insecticide-treated plots in 2002, but no effect of insecticide was seen in 2001. Imazamox slowed the progression of SMV incidence, but the final incidence of SMV-infected plants was the same. Glyphosate had no consistent effect on SMV incidence. Yield was higher in the insecticide-treated plots in 2002, but not 2001. Insecticide and herbicide application had no substantial effects on seed quality.