Threecornered alfalfa hopper infestations are a yearly occurrence in soybeans grown in Virginia’s piedmont region causing economic damage. Additional infestations, and resulting injury, were reported from Virginia’s central and coastal regions in 2020. Threecornered alfalfa hopper injury to seedling or early vegetative soybean can cause plants to break and lodge, and injury is often not detected until stand loss occurs and no remedial action is possible. There is a definite need for to determine management strategies for this pest. The timing and extent of infestations in Virginia, and their damage-causing potential, is poorly understood. The proposed research will take the first steps to characterize infestation timing, yield-damaging potential, insecticide control plans, and cultural control strategies.

Producers have experienced economic yield loss with threecornered alfalfa hopper (3CAH) since 2016, longer in the southern Piedmont, the insect is spreading, and there is potential for widespread injury across the Commonwealth. On-farm research will be conducted to: 1) determine if economical control with insecticides (seed and foliar) can be achieved; 2) determine if losses can be offset with other cultural practices (e.g., seeding rate); 3) develop better understanding the insect’s dependence on environment, cropping system, and neighboring land use on the insect development, infestation level, and timing of infestation; and 4) develop better scouting methods. This project will result in Virginia soybean farmers being better able to effectively control the pest without unnecessary insecticide application and expense.

Data summaries with a brief discussion of progress and results will be compiled and updated weekly throughout the growing season and made available to growers and others in the Ag sector via the Virginia Ag Pest and Crop Advisory.

The project will help Virginia soybean producers improve management of threecornered alfalfa hopper.