By Blake Jackson
Late-season fruits such as strawberries, blueberries, cherries, red and black raspberries, blackberries, and peaches are currently at risk from spotted wing drosophila (SWD). This year, both male and female SWD are appearing simultaneously.
When males identified by the dark spots on their wings-are detected, it’s a clear sign that females are also present and likely laying eggs in ripe fruit.
Evidence of SWD activity includes soft spots on strawberries, juice remaining on raspberry receptacles after picking, pale or softened drupelets on blackberries, and tiny puncture holes in blueberries. However, fruit damage from sunscald due to recent high temperatures, especially in strawberries and blueberries, can sometimes mimic SWD symptoms.
To monitor SWD presence, traps baited with apple cider vinegar, commercial SWD lures, or red sticky cards can be used effectively.
Wherever possible, cultural practices should serve as the first line of defense. Frequent and complete harvesting is key. Any damaged or overripe fruit should be removed and sealed in a bag to prevent further infestation.
In raspberry plots, landscape fabric simplifies ground cleanup. Chilling harvested fruit immediately ideally at 32°F, can slow larval development.
Additionally, keeping plantings well-weeded and regularly pruned improves air circulation and helps treatments penetrate plant canopies more efficiently.
Insecticide sprays can also help manage SWD, but their effectiveness depends on full coverage and consistent application, often weekly. Rotate products to delay resistance. Effective chemical classes include:
- Pyrethroids: Mustang Max, Brigade, Danitol
- Spinosyns: Delegate, Radiant
- Diamides: Exirel, Verdepryn
- Organophosphates (blueberries only): Imidan, higher-rate malathion
- Carbamates: Lannate
For organic production, Pyganic and Entrust are options, though resistance has been observed in some regions. Note that Lannate and Brigade are restricted-use products.
SWD may not be listed on all pesticide labels. In Pennsylvania, such products can still be used if label directions regarding rate, application site, timing, and safety intervals are followed. Always verify product registration and label allowances in your specific state before applying.
Photo Credit: pexels-pixabay
Categories: Pennsylvania, Crops, Fruits and Vegetables