We always receive a lot of questions this time of year about deformed leaflets and thrips. Any cotton grower knows the devastation that thrips can cause on seedlings. These pests are often responsible for the cupping and possum-shaped deformations on cotton seedlings. What about soybean seedlings?
Just like cotton, soybean is a host for many different thrips species. We have done extensive testing of in-furrow insecticides, foliar insecticides and insecticidal seed treatments. While many of these treatments are effective to kill thrips, in over 30 replicated trials across North Carolina and Virginia, they have never provided a yield advantage. We planted beans in April, May and June and have had numbers that exceeded 50 thrips per seedling on soybeans (25x the economic threshold in cotton). In all these cases thrips did not cause injury that resulted in yield loss. Simply put, it is not economical to treat thrips in soybeans.
What do thrips do to soybean seedlings? Using their small needle-like mouthparts, thrips kill individual cells in soybean leaves. This leads to small white specks on the leaves.
