FRUIT AND VEGETABLES
From: Hannah Burrack, Extension Entomologist
What To Watch For: Broad Spectrum Insecticides Can Flare Spider Mites
Broad spectrum insecticides, including materials like pyrethroids (IRAC Group 3 materials), organophosphates (IRAC Group 1B), and carbamates (IRAC Group 1A) (http://www.irac-online.org/eClassification/), have been demonstrated by our laboratory and lots of other entomologists to flare spider mite populations following their use. The reasons each of these classes of insecticides flare mites differ, but the result is the same–more mites following treatment than you start out with.
“. . . A good rule of thumb is to observe at least 10 leaves or leaflets per acre or per variety block, if they are smaller than an acre. Spider mites can be observed and counted with a 10x hand lens. If spider mites are present, the planting should be treated with a miticide before beginning organophosphate or pyrethroid (update: or carbamate) treatments.
Spider mites may not be the only non target (unintentional) pest made worse by SWD treatments. Organophosphates and pyrethroids are broad spectrum materials, meaning they kill many different types of insects, including beneficial predators. The insects these predators may control could increase in their absence, but we cannot necessarily predict which insects these may be. Growers treating for SWD should be vigilant and scout their fields at least weekly to assess whether any new or unexpected insect or damage is present.”
More information
What to watch for: When treating for SWD (NC Small Fruit & Specialty Crop IPM):
What to watch for: strawberry update (NC Small Fruit & Specialty Crop IPM):
All SWD posts (NC Small Fruit & Specialty Crop IPM):