Although this year’s cool start delayed early-season mite pressure, July’s warmer temperatures mean webspinning spider mites, like the Pacific spider mite, are quickly becoming a problem.
“When temps heat up, vines become stressed and vineyards get dustier—conditions conducive to the Pacific spider mite,” says Paul Verdegaal, University of California Cooperative Extension farm advisor for San Joaquin County.
Cold spring weather is also delaying harvest timing, creating a larger window for late-season mite infestations.
“Harvest of early varieties like Pinot grigio (gris) and white zinfandel may be delayed until the end of August,” says Verdegaal. “By that time there could be some mite problems developing, so PCAs and growers need to be keeping an eye out for those pests.”
Mite Monitoring and Management
Verdegaal recommends monitoring selected areas of the vineyard that are representative of the whole. PCAs and growers should also leaf sample regularly—weekly, if possible—for the presence or absence of both Pacific spider mites and beneficial predatory mites. The UC-Davis Insect and Spider Mite Monitoring Form provides detailed sampling instructions and treatment thresholds.
“Over the years, research has shown the presence of predatory mites sometimes allows growers to hold off on miticide applications, which can help reduce input costs and protect against resistance,” says Verdegaal.
However, when PCAs and growers need to spray spider mites there are plenty of options, one of the best solutions for knocking down the mite populations is Acramite® 50WS. Acramite is also safe to the predatory mite protecting that balance of spider mite control from Chemtura AgroSolutions
“A lot of new materials have become available recently, but there’s no one material out there that is the best in every situation,” Verdegaal says. “Examine your situation and ask questions to determine the best material for your vineyard.”
Selecting an appropriate material is only half the battle. Proper use and application are also key components in successful mite management. “When it comes to being successful in business, it’s all about location, location, location,” says Verdegaal. “In our case, you could argue that a successful chemical application is all about coverage, coverage, coverage.”
For tips on effective spray coverage, check out “7 Ways to Keep Chemicals on Target”.