How to Manage Pests

UC Pest Management Guidelines

Adult Pacific spider mite, Tetranychus pacificus. The white nymph of a grape leafhopper, Erythroneura elegantula.


Monitoring Insects and Spider Mites

(Reviewed 7/15)

In this Guideline:

Begin monitoring weekly for mealybugs, leafhopper nymphs, and spider mites together during bloom. Divide the vineyard into quadrants. In each quadrant, randomly select 5 vines each at least a few vines in from the end of the row. Look for mealybugs, leafhoppers, and mites on each of the 20 vines.

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

  • Early in the season, inspect basal leaves for grape, obscure, and longtailed mealybugs and under the bark of trunks for vine mealybug.
  • Later in the season, inspect all plant parts for mealybugs.
  • Make a record of any vine that is infested.
  • On each vine, choose one leaf at the 3rd or 4th node up from the basal node for first generation nymphs or young fully expanded leaves in the middle of the cane for 2nd or 3rd generation nymphs.
  • Count and record the number of nymphs on each leaf using the monitoring form.
  • Note whether they are grape leafhopper nymphs, variegated leafhopper nymphs, Virginia creeper leafhopper nymphs, or a mixed population of multiple species.
  • Check the leaves for parasitized eggs (red, or with parasite emergence holes) and note their presence (+) or absence (-).
  • Follow guidelines in the leafhopper section to determine whether treatment is required.
Spider mites
  • Early in the season, choose one leaf between the 2nd and 4th nodes on each of the 20 vines. Later in the season, choose the 4th expanded leaf from the growing tip.
  • Use a 10–14X hand lens and look for mites and mite predators.
  • Note if mites and mite predators are present (+) or absent (-) on the monitoring form.
  • Follow guidelines in the webspinning spider mite section to determine whether treatment is necessary.



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Grape
UC ANR Publication 3448

General Information

L. G. Varela (Crop Team Leader), UC IPM Program, Sonoma County
W. J. Bentley, UC IPM Program, Kearney Agricultural Research Center, Parlier
D. R. Haviland, UC IPM Program, Kern County
P. A. Phillips, UC IPM Program, Ventura County
R. J. Smith, UC Cooperative Extension Sonoma County
A. Shrestha, UC IPM Program, Kearney Agricultural Center, Parlier

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