Kelley Tilmon, OSU Extension Field Crops Entomologist reminds soybean growers to scout for stink bugs in soybeans and provides the following information and recommendations:
As our beans start to put on pods, it’s time to start scouting for stink bugs. In 2016, a number of farmers had significant stink bug damage but didn’t realize it until harvest, when they discovered shriveled, blasted seeds. Prevent seed damage by scouting and applying rescue treatment at appropriate threshold levels.
Several species of stink bugs are found in soybeans. These include the green, the brown, the red shouldered and the brown marmorated stink bug. Both nymphs (immatures) and adults feed on the developing seed by using their piercing/sucking mouthparts to poke through the pod. Seed fed upon by a stink bug will have a flat or shriveled appearance within the pod. Another stink bug found in soybean fields, the spined soldier bug is actually a beneficial insect. The spined soldier bug looks similar to the brown stink bug, but has sharper points on its shoulders, and is more brown on the underside (the brown stink bug is actually more green underneath).
Generally, the damage caused by stink bug feeding is not seen until harvest time, because the pod usually retains its shape, despite the smaller seed. Therefore, it is important to scout early and control if necessary. Most insecticides labeled for soybean include stink bugs on the label, and most are adequately effective. Keep in mind it is easier to kill immatures than adults. To sample for stink bugs, take multiple 10-sweep samples with a sweep net in multiple locations throughout the field. Often stink bugs start on field edges, particularly if there are woodland field borders. Concentrate sampling in those areas first. Average the number of stink bugs in the 10-sweep samples. The threshold to treat is four or more stink bugs (adults and nymphs combined). If soybeans are being grown for seed, the threshold can be dropped to two or more stink bugs.
For more information about how to identify stink bugs or how to scout for stink bugs in soybeans, contact the Wayne County Extension office at 330-264-8722.