Andy Michel, Ohio State Extension
Japanese Beetles on Soybean Plants
Last week, I had a chance to scout some very early planted soybean that was in the R1 and R2 stages. A couple of observations:
Japanese beetles and other defoliators: There was a presence of general defoliators in soybean. Our two most common insects are bean leaf beetles and Japanese beetles. While the BLBs were fairly hard to find, Japanese beetles were easier to spot. However, most of the defoliation was light and only present on the top leaves. Remember—it takes a fair amount of defoliation before soybean yield is impacted. The thresholds for defoliation are 40% before bloom, 15% bloom to pod-fill, and 25% after pod fill. But also keep in mind that these thresholds are based on the whole plant, not just the upper portions. Additionally, most Japanese beetle defoliation occurs along the edge, so make sure you check the entire field.
Stink bugs: Surprisingly, I collected a fair amount of green and brown stink bug adults, as well as some stink bug egg masses. These eggs will hatch about the time soybean enters the pod stage, where they will then feed on the developing seed. While we are not at the time where a spray would be necessary, all soybean fields will need to be scouted over the next week for the continued presence of stink bugs.
Source : osu.edu