Spotted wing drosophila in tree fruit
Scientists have developed a plan to help growers manage a new pest that threatens cherries and more.
Use apple cider vinegar traps to monitor orchards for spotted wing drosophila.
Steve Castagnoli, Oregon State University
University entomologists from Washington, Oregon, and California are collaborating to provide recommendations for growers facing a new and invasive pest, the spotted wing drosophila. As information from California (where the pest was first discovered) is shared and updated, recommendations may change, as is the case with trapping methods discussed below.
In the latest update from Oregon State University, apple cider vinegar traps are now recommended, instead of earlier versions that used yeast, sugar, and water, with yellow sticky cards. For trapping, use quart-sized, clear deli containers with numerous 3/16-inch holes drilled in near the top. Fill the container with an inch of apple cider vinegar, a couple drops of unscented dish soap, put a lid on it and hang three to five feet from the ground. Monitor the trap weekly, replacing the vinegar (disposing the vinegar away from the monitoring site).
OSU has compiled a chart of insecticides registered for use against the spotted wing drosophila on several tree fruit and berry crops: Insecticides registered for SWD in Oregon. Information from California shows that cherries are susceptible from light straw color through harvest and beyond. In choosing insecticides, growers must consider re-entry periods, pre-harvest intervals, and maximum pesticide residue limits of export markets. Malathion EC has shown phytotoxicity in some California cherry orchards.
Integrated management plant
A plan for integrated management of spotted wing drosophila has been developed for Pacific Northwest cherry growers, and includes:
- Monitoring orchards and surrounding areas with traps
- Managing alternate host plants in surrounding habitat
- If spotted wing drosophila is NOT found, follow normal cherry fruit fly program
- If spotted wing drosophila IS found, treat crop with ‘preferred’ insecticides (see insecticide list referred to above)
- Rotate insecticide chemistries for resistance management
- Continue to monitor with traps to determine control program effectiveness
- Sample fruit for infestation using the fruit-dunk flotation method
- Consider postharvest clean-up spray to reduce population
- Stay informed. Visit OSU’s spotted wing drosophila Web site: swd.hort.oregonstate.edu