During 2013-2015, two field locations were established each year. Plots were set up in a randomized complete block design with four replications, including different foliar insecticides, insecticidal seed treatments and host plant resistance. Soybean aphids were sampled weekly and an estimate of seasonal exposure was estimated for each treatment. Yield was also evaluated for each treatment.
Results of the 3-year study:
• Foliar insecticides labeled for soybean aphid were efficacious; meaning they all had good knockdown or killing power.
• Insecticidal seed treatments could reduce cumulative aphid days, but did not offer sufficient yield protection compared to foliar insecticides.
• Host plant resistance did reduce cumulative aphid days and were comparable to foliar insecticides in yield protection; however, yield potential of host plant resistant varieties was lower compared to susceptible soybean varieties.
Conclusions of the 3-year study:
• Farmers have a wide range of foliar insecticides to choose from if they need to protect yield from a soybean aphid outbreak.
• Scouting and timely treatment with foliar insecticides is recommended over the use of prophylactic seed treatments.
• Using host plant resistance dramatically decreases the likelihood a foliar insecticide will be needed to protect yield.