Fickle weather conditions are keeping spider mites away from California vineyards. Cooler-than-normal temperatures have been followed briefly by a hot spell in some areas, only to return again to cool. PCAs report a little mite pressure, but over all it is spotty.

“Mite species and densities are usually more location-specific and related to water, dust and pesticides applied than dependent on statewide temperatures,” says Frank Zalom, entomologist at University of California, Davis. “That said, being a relatively cool spring I would expect that mite densities would stay relatively moderate until things start to warm up consistently and vines start to get more water stressed.”

“This might be a good year for Willamette mites to develop in areas that usually have them, Zalom says. “Temperatures later in the summer will have more impact on what we might see relative to Pacific mite densities.”