The impacts of chemical management on threecornered alfalfa hopper populations in Mid-Atlantic U.S. soybean

The threecornered alfalfa hopper, Spissistilus festinus (Say) (Hemiptera: Membracidae), is a ubiquitous pest of soybean that can cause lodging by girdling soy plants, ultimately leading to yield loss in certain scenarios. Plant lodging and significant stand loss from this insect has occurred in Virginia's piedmont since at least 2017. There is a need to determine if chemical control (e.g. foliar) can be used to minimize plant injury and preserve yield. We hypothesized that control with insecticides would vary depending on infestation timing, which was not known, and foliar insecticides will provide the best control when applied at or near the time the pests arrive. In 2021, we evaluated spray timings based on plant development, and estimated infestation timings using yellow sticky traps and timed visual observations. In 2022, we will continue to monitor S. festinus populations and the impacts of the spray tests. We will address the accumulated results for this project.