Several Extension educators, specialists, and growers have been diligently trapping for spotted wing Drosophila (SWD) in berry crops at multiple sites across 20 counties in Ohio since June. In general, SWD populations at most locations have peaked at this point, but they can remain abundant for several weeks longer. Even after the first frost, some SWD adults are usually active in the field.
At some monitoring sites where growers have been spraying through the season, we are still able to trap SWD adults. Adults are also being trapped at sites where fruit is no longer being produced. While this is concerning to growers with fruit still in the field, there doesn’t seem to be any significant fruit infestation or damage, which is good news. If you haven’t kept up on your spray schedule and still have fruit out in the field, it is strongly recommended that you check your fruit with a simple salt water test to see if you have any infested fruit. Here are the directions from an OSU factsheet (https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/1/8311/files/2017/04/SWD-salttesthandout-updated-pnd335.pdf) or via an OSU IPM YouTube video (https://www.youtube.com/watch?v=MtMXHxqcSVs).
Our closing message is that if there is still fruit on your farm worth harvesting, keep up on your spray schedule in order to protect those fruit from infestation. If you deem it necessary to spray for another few weeks, it is important to keep an eye on the PHI of products used. Most PHI’s range between 0-7 days, but some products labeled for grapes have a 30-day PHI. Here is the complete list of insecticide PHIs and maximum number of applications allowed: https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/1/8311/files/2017/02/SWD_insecticideOptions2018-1ppr7m8.pdf.