Pest Control Tips: Preventing Harms of Spotted Wing Drosophila on Blueberries

Fight the threat of Spotted Wing Drosophila in blueberries with Kemin's botanicals

Harms Caused by Spotted Wind Drosophila in Blueberries

Spotted wing drosophila can infest plants that are not yet damaged or overripe, making them more of a threat than typical vinegar flies. Vinegar flies lay their eggs in overripe and rotting fruit however, SWD are able to lay their eggs into intact fruit due to the female's serrated ovipositor. She is able to saw into the flesh of the fresh fruit, which is typically too firm for other species of vinegar flies. Then SWD lays eggs into the maturing blueberries, and the larvae feed on the fruit pulp. If berries containing the pest are harvested and contained together, all blueberries exposed to the infested berries can be downgraded or rejected from selling¹.

Preventing infestations

1. Monitor fields for SWD

To monitor your field for SWD, food-baited traps can be used. This form of testing does not give a direct measure of infestation levels but can show early signs of pest presence. However, food-baited traps will not work for detecting larvae. Because the market has zero tolerance for larvae in fruit, a fruit dunk flotation test should be done².  Carefully monitoring your crops using multiple testing and trapping methods can give early detection of SWD.

2. Use preventative sprays

One of the best ways to prevent infestations is to act BEFORE the pest is present. Using a proactive approach with early-season sprays of botanicals directed at target pests can stop an infestation before it happens. Act early and plan your IPM program to prevent pests rather than fight the problem after an infestation has started.

3. Rotate the products used in your IPM program

Specialty crop growers committed to reducing insecticide resistance create an IPM program that includes various chemicals with different modes of action in rotation. Growers must update their rotation programs to avoid pests growing resistant to the chemicals used over time. Many chemicals have limited sprays that can be applied per season. Alternating with softer chemicals that do not have this limitation can help growers avoid using their hard-hitting chemistries too early and being left with very few chemical options by the end of the season. 

4. Harvest frequently and remove leftover fruit to avoid breeding

SWD are attracted to ripe, overripe, damaged, and rotting fruits¹. Fruit needs to be harvested quickly after ripening to lessen the amount of time spent in the field and limit its exposure to the SWD. Remember that SWD are attracted to ripening, ripe, overripe, damaged, and rotting fruit. A helpful tip is to understand your chemistries' re-entry interval and to use caution when applying harsh chemicals that could delay harvesting. 

Works Cited:

¹https://site.caes.uga.edu/blueberry/swd/#:~:text=Blueberries%20are%20susceptible%20to%20SWD,fruit%20using%20its%20serrated%20ovipositor.

²https://catalog.extension.oregonstate.edu/em9267/html#:~:text=Spotted%2Dwing%20drosophila%20(SWD),tolerance%20for%20larvae%20in%20fruit

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