Agriculture: Grape Pest Management Guidelines

Delayed-Dormant and Budbreak Monitoring (Wine and Raisin Grapes)

Monitor vines, spurs and canes once during the delayed dormant season and once at bud break to check for cutworms, mealybugs, ants, thrips, and mites. Spurs are one-year-old canes that were pruned back to 1 to 2 buds at pruning.

Use monitoring form with detailed treatment threshold information (example formPDF).

How to Sample

  1. On a warm day (65°F or above), monitor 20 vines by looking at 5 randomly selected vines per quadrant of the vineyard. For the best estimate of pest distribution, monitor fewer vines in more locations. Be sure to include those areas, however, where you have noticed pests in the past.
  2. Monitor vines following the guidelines below. For spur monitoring choose a spur on the basal portion of a cordon closest to the crown.
  3. Record your observations on a monitoring form.

Procedure and Treatment Thresholds

Pests Monitoring procedures Treatment threshold
Cutworms
  • Examine 5 buds for damage (hollowed buds).
  • If damage is present, look for cutworms under bark, on cordons, trunk, and at soil level.
Don't treat if less than 4% of the buds per location are damaged.
Pseudococcus mealybugs (grape, obscure, longtailed)
  • Look for crawlers under loose bark at the spur tip or on canes.
  • Along Central Coast, also look for more mature obscure and longtailed mealybugs at base of spur, under bark.
Treat if 1 out of 5 spurs is infested.
Vine mealybug
  • Look for nymphs and females under bark at graft union, in old pruning wounds in the trunk, and below the base of the spur (old remnant egg sacs may be found).
  • In sandy soils, look at soil level and at roots.
Treat during the delayed dormant period and again at bloom if vine mealybug is present. For heavy infestations, consider removing bark before spraying trunk and cordons.
Ants
  • Look for ants. If found, look more closely for mealybugs or European fruit lecanium scale.
Identify areas of concern for spring monitoring.
Mites
  • Look under loose bark on spur tip for orange overwintering form of Pacific or Willamette spider mite.
Identify areas of concern for bloom monitoring.
Thrips
  • Open shoots or gently tap buds over white paper to check for thrips.
Treatment may be necessary if damage increases and temperatures remain cool.

Important Links

Text Updated: 07/15