Grape erineum mite

Systematic position: The grape erineum mite (Colomerus vitis, syn. Eriophyes vitis) is a member of the family Eriophyidae, which belongs to the order Acariformes. These are microscopic, worm-like mites that are barely visible without strong magnification.

Host plants: This pest is specialized in attacking members of the Vitis genus. While it is rarely fatal to the vine, it is a significant pest in commercial viticulture worldwide, impacting both plant vigor and overall harvest potential.

Biology and life cycle: Adult females overwinter in protected areas of the vine, primarily under bark scales and inside dormant buds. As temperatures rise in spring, they migrate to the developing foliage. The mite reproduces rapidly, completing multiple generations throughout the season, which allows for a high population density if left uncontrolled.

Damage and pest status: The mite feeds on the lower leaf surface, causing the vine to produce an abnormal growth of hairy, felt-like tissue known as an erineum. These patches are initially white or yellow and later turn reddish-brown. While the damage is often cosmetic, severe infestations can significantly interfere with the photosynthetic capacity of the leaves.

• Apply dormant-season sprays to reduce overwintering populations.
• Use sulfur-based acaricides during the active growing season.
• Maintain proper canopy management to ensure good coverage during spraying.
• Monitor vines closely during spring bud burst to catch early infestations.
• Remove and destroy heavily infested prunings to reduce the inoculum level.