Erenium mites ?

Asked August 6, 2018, 11:49 PM EDT

Last year I had one or two vines with galls on the leaves in Siegerrebe grapes . This year many more vines were infested with galls which I was assuming was erenium mites. Now mid to late season there is severe damage with massive involvement and extensive leaf damage. I’ve not used sulfur for the past two years. I imagine it’s too late for this season. Am I right about the mites and what should I do organically.

Island County Washington

1 Response

You are correct in that the symptoms are erineum mites (also called blister mites), and that it's a bit late to control for this season. Once the mites are in the blister form, they are hard to control (i.e., they are protected from insecticides).

Typically, early-season application of wettable sulfurs, or horticultural oils, will help keep the blister mites in check, as it targets the larvae as they move from their overwintering stage in bud scales, out to new leaves. I would recommend going back to using sulfur in your early-season sprays for next year to try and get the populations back in-check.

Below is a link with a brief description on the mite (just for reference):

The leaves with isolated blisters are likely still functional enough to ripen fruit. The leaves where the entire back side is covered (like in your last picture), are no longer offering anything to the plant, so if you want to strip those off (which will also remove some of the mites for next year), that might help with the problem (but again, helping for next year).