Unusually High Spotted-Wing Drosophila Pressure

Unusually High Spotted-Wing Drosophila Pressure

The invasive spotted-wing drosophila (SWD) is the key insect pest of soft-skinned fruit across the United States. With the recent wet weather, we have been experiencing higher than normal spotted wing drosophila (SWD) pressure. Depending on the intensity and amount, rain also substantially reduces insecticide residual activity against SWD; 0.8 inches will drop percent control for most insecticide products even at 3 days after treatment.¹ Therefore, reapplication after rain is the best bet. If producers cannot shorten their intervals or reapply, they might consider products like Mustang Maxx (zeta-cypermethrin) or Exirel (cyantraniliprole) which seem to be more rainfast than Delegate (spinetoram) or malathion.¹,²,³

Applied entomologists across the United States were asked to provide their relative ranking of insecticide performance against SWD under field conditions, across multiple crops (cranberries, cherries, and blueberries) and different regions (CA, OR, WA, MI, ME, NY, NJ, NC, GA, FL) with a scoring system of 0 = ineffective, 1 = weak, 2 = fair, 3 = good, and 4 = excellent. The most recent rankings were summarized in 2021.⁴ These rankings along with the active ingredient, IRAC code, crop that they can be used on, and pre harvest and reentry intervals are provided in Table 1. The final decisions on which insecticide to use should be based on whether it is registered for your crop, the pre-harvest interval, the cost, and also its suitability for helping to manage insecticide resistance. As always, rotate modes of action, ensure good spray coverage, and follow all label instructions.