–by Jeff Whitworth, Field Crops — Entomologist
Soybeans finally seem to be starting to grow and develop a little since receiving some moisture and cooler weather. So, as the beans grow so do the soybean pests. Probably the number one pest all across the Midwest soybean growing regions is the bean leaf beetle (see fig 1). This time of year these beetles are feeding a little, which often causes the characteristic round and/or oblong holes in leaves (see fig 2), but also are actively depositing eggs in the soil around soybean stems. When this next generation of adults emerge then they will become active foliage feeders, and sometimes feed on succulent green pods-which may affect the bean inside the pod.
Figure 1: Bean leaf beetle
Figure 2: Leaf damage from bean leaf beetle
Green stinkbug adults (see fig 3) are also very active this time of year, much like adult bean leaf beetles, feeding a little but also depositing eggs. These eggs will be hatching over the next few weeks and the small stinkbug nymphs will also be very active sucking juice from host plants. Thus, as these soybeans grow and develop so will the pests. This indicates that monitoring should be initiated then in the next couple of weeks–or at least as the beans start into the reproductive phases, at which time they are at their most vulnerable to pest attack.
Figure 3: Adult green stink bug
(Photos by Cayden Wyckoff)