grape leaf problems

Asked May 25, 2018, 11:10 PM EDT

the leafs on my grape plants hav what appears to be bubbles on the top of the leaf and small clusters of webbing on the underneath of the leaf. what can it be and how can i get rid of it?

Clackamas County Oregon

1 Response

More than likely, the damage is due to erineum mites, Colomerus vitis, an occasional, but unimportant, pest of grapes.

Even though it appears as it might be a serious problem, the grape vine will thrive and produce a normal crop of fruit. As time goes by, the normal progression of the white areas on the undersides of the leaves will change to tan and, finally, brown.

Erineum mites are very different in size and shape than the more common spider mites you may be familiar with. They’re microscopic in size, elongated, and pale yellow. Because they overwinter under bud scales, they’re able to feed on the newly expanding leaves. Environmental conditions this year are such that their populations have surged. This year, we’re receiving numerous inquiries from gardeners.

Fortunately, the damage is only esthetic. Pesticides aren’t needed against these particular mites because their feeding doesn’t affect grape yield, quality, or flavor.

If the images on this page, don’t match what you see on your grape, please send several images: /the grape overall and a close view (top & bottom) of an affected leaf. See http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/PESTS/grerineummte.html.