The grapevine bud mite.
An account is given of the bionomics, injuriousness and control of the grapevine bud mite [Colomerus vitis], which seriously damages grapevines in the Crimea, USSR. The fertilized females overwinter beneath the outer bud scales, ovipositing at the base of the young shoots when the eyelets appear. The larvae severely damage the shoots, of which 20-30% generally, but sometimes up to 80-100%, show retarded growth on susceptible varieties. The larvae later migrate and feed where the axillary buds are forming and on the young forming leaves and the side shoots. There are 4-6 generations a year. The leaves remain small, and young shoots may dry out. Although there is some growth regeneration the yield is reduced. In the absence of control measures the plants dry out in 3-4 years. Spraying with DNOC at the beginning of April prior to bud burst has proved the most effective measure, concentrations of 0.5 and 1-2% being 95 and 100% effective, respectively, and eliminating damage to the shoots.