Phil Mulder, Oklahoma State University
The tiny (1/15-inch diameter) scale-like bumps that appear on the cane are evidence of last year’s problem. These bumps are pale yellow to brown, with a pale nipple to one side of the center. Scale infestations are found on two-year-old wood.
- When canes are pruned in late winter, check carefully for evidence of scale insects. Flag or mark scale-infested canes and even prune out heavily infested areas.
- Monitor using double-stick tape on infested canes.
- If old scale is evident, watch the infested vine for activity of young or the crawler stage. Use a sewing pin to gently lift the old scale up and glance underneath. A 10X hand lens will work to scout for the nymphs. Do this about twice per week until you see nymphs.
- If crawler activity has begun, apply a delayed dormant spray of superior oil to the canes. Start treatment for this pest and European red mite just before buds begin to show green.
The overwintering female (wingless) gives birth to 30 to 50 live young in the spring. Grape scales overwinter on the cane and under loose bark. Crawlers from the first generation become evident in mid-spring.
Grape Scale, Virginia Tech
Field Guide for Integrated Pest Management in Pacific Northwest Vineyards. Washington State University
Reviewed by Eric Stafne, Mississippi State University and Tim Weigle, Cornell University