Japanese beetles, grasshoppers, spider mites, rootworm, gall midge on radar
Iowa State University Extension reports there are many pests to watch for heading into July but few of economic concern at this point. “It seems like July is the peak of insect activity and some spill over to row crops,” said Erin Hodgson, ISU Extension entomologist. “We track a few key insects every year, and they are developing a bit more quickly compared to an average year because of accumulated heat units.”
Hodgson identified these pests on the radar for 2023:
Japanese beetle — They can be frustrating for farmers throughout Iowa because they have a wide host range and cluster in big groups. Their defoliation can be significant, especially along the edge rows; however, it isn’t generally of economic concern.
Grasshoppers — Several species are active in the state right now. They also have a wide host range but tend to be more noticeable as a crop pest in prolonged drought. Consider them a field-edge pest and particularly difficult to manage if the defoliation becomes severe.
Spider mites — They thrive in hot and dry weather and can be especially difficult to manage without multiple foliar applications.
Corn rootworm — The larvae are finishing up feeding on roots, and adults are showing up now. When corn silks appear, it is a good reminder to assess root injury and evaluate future management decisions. Continuous corn fields are of notable concern for substantial yield losses from the larval feeding. Hodgson said she is hearing about injury to first year (rotated) corn this year.
Soybean gall midge — This new pest is found throughout the western half of Iowa. Scouting along field edges will confirm the presence of this pest. Rapidly wilting or dying plants can be confused with many other issues, so split stems and look for orange larvae.