SPIDER MITES

Spider mites are occasional pests of grapes but not of Concords. At least two species of spider mites have been found on Washington wine grapes: the two spotted spider mite, Tetranychus utticee, and the McDaniel mite, T. mcdanieli. Economically damaging spider mite populations in agriculture are invariably the result of ecosystem disruption usually caused by broad-spectrum pesticides, including sulfur, that suppresses the activities of spider mite predators. Mites are usually not abundant in Washington wine grapes, indicating that the system is not greatly disrupted. Leafhopper sprays are probably most responsible for disruption although recent information shows that sulfur can reduce predatory mite populations and increase spider mites. We have found at least four species of predatory mites on grapes. These have been tentatively identified as Galendromus occidental is (the most common), Metaseiulus citri, Typhlodromus caudiglans, and Amblyseius andersoni. For more information, see our spider mite listing under hops.

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