LEXINGTON, Ky. — The hot, dry conditions we experienced earlier this month have brought on two-spotted spider mite problems in some areas. Unlike many insect problems, we are alerted to mite infestations by the symptoms of their damage rather than seeing the mites themselves. Common symptoms of spider mite damage include stippling of leaves, webbing, and minute flecking on surfaces of harvested fruit.
Stippling consists of small light-colored spots in the leaves. These are often grouped in small patches when spider mite populations are low and can cover large portions of the plant when infestations are high. Spider mites can produce silk, which gives rise to their name ‘spider’ mites. This webbing isn’t noticeable when populations are low, but as mites increase in number, webbing may be seen between leaf petioles and stems or leaflets. Mites feeding on fruit with their piercing sucking mouthparts cause similar stippling, which is sometimes referred to as gold flecking on tomatoes.
When spider mite problems need to be controlled midseason, I generally recommend only miticides that provide high levels of control (see the efficacy table chart in the back cover of Vegetable Production Guide for Commercial Growers, ID-36). Situations closer to harvest may be managed with products providing only temporary relief.
— Ric Bessin, University of Kentucky Extension Entomologist
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