How to Manage Pests

UC Pest Management Guidelines

Begin monitoring weekly for grape mealybug, leafhopper nymphs, and spider mites 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 (127KB, PDF) with detailed treatment threshold information.

Grape mealybug: (View photos of mealybugs.)

• Choose 20 vines from different areas of the vineyard.
• Inspect 1 spur per vine to determine how many of the 20 vines are infested.
• Record each vine that has a spur with grape mealybug on a monitoring form.
• Follow guidelines in the MEALYBUG (PSEUDOCOCCUS) section to determine whether treatment is needed.

Leafhoppers: (View photos of leafhoppers and natural enemies.)

• 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, or both.
• 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: (View photos of spider mites and natural enemies.)

• 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.

PDF: You need a PDF reader, such as Acrobat Reader version 5 or later, to view or print this PDF. If no reader is installed on your computer, you can download a free copy of Adobe Acrobat Reader.

PUBLICATION

UC IPM Pest Management Guidelines: Grape
UC ANR Publication 3448
General Information
W. J. Bentley, UC IPM Program, Kearney Agricultural Research Center, Parlier
L. G. Varela, UC IPM Program, Sonoma Co.
F. G. Zalom, Entomology, UC Davis
R. J. Smith, UC Cooperative Extension, Sonoma Co.
A. H. Purcell, Environmental Science, Policy and Management, UC Berkeley
P. A. Phillips, UC IPM Program, Ventura Co.
D. R. Haviland, UC IPM Program, Kern Co.
K. M. Daane, Kearney Agricultural Research Center, Parlier
M. C. Battany, UC Cooperative Extension, San Luis Obispo Co.

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