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How to Manage Pests

Interactive Tools and Models:
Grape Powdery Mildew Risk Assessment Index

The grape powdery mildew risk assessment index (RAI) is useful for determining disease pressure and how often you need to spray to protect the vines. For information on how to use the RAI, see the pest management guideline.

Powdery mildew risk for stations in counties:
| Fresno | Madera | San Joaquin |
Choose year

RAIs are based on actual weather data for stations that take appropriate readings.

County Active weather stations
(Click on station for year-to-date graph/daily data)		 RAI*
for
05/11/2008		 Disease pressure Pathogen status
Fresno
(map)		 Based on bud break, March 11, in Thompson Seedless,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
CARUTHERS-01.P, CAR 90 high reproduces every 5 days
Del_Rey/Fowler-01.P, DELF 80 high reproduces every 5 days
EASTON-01.P, EAS 90 (S1) high reproduces every 5 days
KERMAN-01.P, KER 90 high reproduces every 5 days
KINGSBURG-01.P, KNG 90 high reproduces every 5 days
Kearney_Ag_Ctr-01.P, KAC 90 (S1) high reproduces every 5 days
SAND_RANCH-01.P, SR1 90 (S1) high reproduces every 5 days
Madera
(map)		 Based on bud break, March 11, in Thompson Seedless,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
FIREBAUGH/ALISO-01.P, FRBA 80 high reproduces every 5 days
Madera_North-01.P, MADN 80 high reproduces every 5 days
Ripperdan-02.P, RIP 90 high reproduces every 5 days
San Joaquin
(map) 		Based on bud break, March 12, in Chardonnay,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
FARMINGTON-01.P, FGN 100 high reproduces every 5 days
LINDEN-01.P, LIN 100 high reproduces every 5 days
LIVE_OAK-01.P, LIV 100 high reproduces every 5 days
LOCKEFORD-01.P, LOC 100 high reproduces every 5 days
LODI-01.P, LOD 100 high reproduces every 5 days
PETERS-01.P, PET 100 high reproduces every 5 days

*   Bud break based on farm advisor countywide vineyard surveys:

  • Fresno: March 11 in Thompson Seedless
  • Madera: March 11 in Thompson Seedless
  • San Joaquin: March 12 in Chardonnay

S1 = missing data substituted with values from CARUTHERS-01.P

Because estimated data are included in the index, use reported RAI with caution. Interpret RAI using field surveys and your knowledge of the particular vineyard, along with additional weather data if you have it.

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Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2008 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See How to manage pests, or in the U.S., contact your local Cooperative Extension office for assistance. web template revised: May 13, 2008 Contact webmaster.