UC IPM Online UC ANR home page UC IPM home page

UC IPM Home

SKIP navigation

 

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 | Lake | Madera | Amador | Calaveras | El Dorado | 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
05/22/2017
Disease pressure Pathogen status
Amador
(map)
Based on bud break, March 30, in Zinfandel,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Amador_Eagle-01.P, EAG1, Screaming Eagle 30 intermediate reproduces every 15 days
Amador_Renwood-01.P, REN1, Renwood Winery 30 intermediate reproduces every 15 days
Calaveras
(map)
Based on bud break, March 30, in Chardonnay,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Ironstone-01.P, IRN1, Ironstone 70 high reproduces every 5 days
West_Point-01.P, WES1, West Point 70 high reproduces every 5 days
El Dorado
(map)
Based on bud break, March 30, in Chardonnay,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Fair_Play-01.P, FAI1, Fair Play 100 high reproduces every 5 days
Gold_Hill-01.P, GLD1, Gold Hill, Saureel Vineyards 60 high reproduces every 5 days
Lava_Cap-02.P, LAV2, Lava Cap 70 high reproduces every 5 days
Fresno
(map)
Based on bud break, March 9, in Thompson Seedless,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
CARUTHERS-01.P, CAR 60 high reproduces every 5 days
Del_Rey/Fowler-01.P, DELF 60 high reproduces every 5 days
EASTON-01.P, EAS 50 intermediate reproduces every 15 days
KERMAN-01.P, KER 60 high reproduces every 5 days
KINGSBURG-01.P, KNG 60 high reproduces every 5 days
Kearney_Ag_Ctr-01.P, KAC 60 high reproduces every 5 days
SAND_RANCH-01.P, SR1 60 (S1) high reproduces every 5 days
Lake
(map)
Based on bud break, March 31, in ???,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
KELSEYVILLE-01.P, KEL 0 n/a no infection
MIDDLETOWN-01.P, MID 0 low is present
Scotts_Valley-02.P, SVL 0 (S2) n/a no infection
Upper_Lake-02.P, UPL 0 n/a no infection
Madera
(map)
Based on bud break, March 13, in Thompson Seedless,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
FIREBAUGH/ALISO-01.P, FRBA 20 low is present
San Joaquin
(map)
Based on bud break, March 14, in Chardonnay,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Collegeville-02.P, COL2 40 intermediate reproduces every 15 days
LIVE_OAK-01.P, LIV 40 intermediate reproduces every 15 days
LOCKEFORD-01.P, LOC 10 low is present
LODI-01.P, LOD 60 high reproduces every 5 days

*   Bud break based on farm advisor countywide vineyard surveys:

  • Fresno: March 9 in Thompson Seedless
  • Lake: March 31 in ???
  • Madera: March 13 in Thompson Seedless
  • Amador: March 30 in Zinfandel
  • Calaveras: March 30 in Chardonnay
  • El Dorado: March 30 in Chardonnay
  • San Joaquin: March 14 in Chardonnay

S1 = missing data substituted with values from CARUTHERS-01.P
S2 = missing data substituted with values from KELSEYVILLE-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.

Top of page


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright 2017 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 our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   web template revised: May 23, 2017 Contact webmaster.