2.4.3.g Blister mite or grape bud mite disease

What damage do blister mites cause in the vineyard?

In the spring, greenish and then reddish blister galls with a volume of 0.5 to 5 cm2 can be observed on the upper surface of young leaves, corresponding to a dense white or pinkish felting on the lower surface, caused by local hypertrophy of the epidermal hairs of the leaf.
As the galls age, the felting turns reddish brown. The mites (Eriophyes vitis) attack new leaves as the canes grow. The damage is usually limited and does not cause any reduction in yield. In the case of violent attacks in spring, blister mites can hinder the development of young shoots and cause flower abortion with a significant loss of harvest.

How can blister mites be recognized?

The adult is invisible to the naked eye (160 microns x 30 microns) and has an elongated worm-shaped appearance. Creamy white in colour, it has two pairs of legs in front, and is decorated transversely with about 80 granular ridges. The males are smaller than the females. The larvae differ from the adults only by their smaller size. The eggs are spherical, smooth and translucent.

What is the biology of Eriophyes vitis?

In winter: the females gather either under the first bud scale layer, or under the bark, at the base of the branches.

In spring: the females leave their shelters at the C stage and spread out over the young leaves where their feeding causes the formation of galls. The eggs are deposited in the felt covering the gall. Development from egg to adult takes 15 days. The first-generation adults migrate from the attacked leaves to the terminal bud and the young leaves. This migration continues throughout the growth period and continues into the summer. Five to seven generations can occur.

In autumn: the adults leave the foliage and go down to the base of the canes.

How can this pest be controlled?

Biological: There is a midge that is a specific predator of the blister mite: Arthrocnodax vitis Rubs. Other predatory mites such as typhlodromes can also help to control this pest.

Chemical: There is no intervention threshold. Control is curative and should be limited to infected plots. Treatment with wettable sulphur, as soon as the galls appear, at the registered dose for powdery mildew, is generally sufficient to control grape bud mite disease. In the case of sensitive plots, two treatments (stages C-D and D-E) may be required.

Extract from Vigne Vin Occitanie.