Spotted wing drosophila (SWD) is active across the state and has been detected at all of our cooperating field sites. Moderate to high levels of SWD are being trapped around the state as can be seen from the map (Figure 1). This indicates that crops being harvested are at moderate to high risk of SWD fruit infestations. The crops most at risk include blackberries, blueberries, raspberries. and grapes.
Management with Insecticides
Producers who are spraying insecticides for SWD on a 7-day schedule and obtaining good coverage are having good results. This program can keep SWD at very low levels or even eliminate SWD for trap catches. But keep in mind that we need to rotate modes of action with our SWD sprays. Ideally we should be using three modes of action in a rotation so we are not using the same spray with consecutive applications. Rotating modes of action helps to prevent insecticide resistance with all of the sprays we use.
Other Management Practices
Other practices to help reduce spotted wing drosophila include clean picking, more frequent picking, and immediate cooling of berries after harvest.
- Clean picking involves removing all ripe berries from plantings, including those that are damaged and unmarketable. This reduces the number of successful breeding sites for spotted wing drosophila.
- Frequent picking reduces the length of the exposure period to SWD egg laying.
- Rapid cool down after harvest suspends development and cooling near freezing for several days can kill a high percentage of spotted wing drosophila. Home gardeners can freeze their berries to kill any SWD.
By Ric Bessin, Extension Entomologist