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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 | 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
06/26/2016
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 20 low is present
Amador_Renwood-01.P, REN1, Renwood Winery 20 low is present
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 20 low is present
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 60 high reproduces every 5 days
Gold_Hill-01.P, GLD1, Gold Hill, Saureel Vineyards 20 low is present
Lava_Cap-02.P, LAV2, Lava Cap 20 low is present
Fresno
(map)
Based on bud break, March 3, in Thompson Seedless,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
CARUTHERS-01.P, CAR 20 (E) low is present
Del_Rey/Fowler-01.P, DELF 0 low is present
EASTON-01.P, EAS 0 (E) low is present
KERMAN-01.P, KER 40 (E) intermediate reproduces every 15 days
KINGSBURG-01.P, KNG 0 (E) low is present
Kearney_Ag_Ctr-01.P, KAC 0 low is present
Laton_North-01.P, LATN M    
SAND_RANCH-01.P, SR1 10 (S1) low is present
Madera
(map)
Based on bud break, March 3, 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
Madera_North-01.P, MADN 20 (S2) low is present
San Joaquin
(map)
Based on bud break, March 2, in Chardonnay,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Collegeville-02.P, COL2 10 low is present
LIVE_OAK-01.P, LIV 20 (P) low is present
LOCKEFORD-01.P, LOC 0 low is present
LODI-01.P, LOD 20 (P) low is present
PETERS-01.P, PET M    

*   Bud break based on farm advisor countywide vineyard surveys:

  • Fresno: March 3 in Thompson Seedless
  • Madera: March 3 in Thompson Seedless
  • Amador: March 30 in Zinfandel
  • Calaveras: March 30 in Chardonnay
  • El Dorado: March 30 in Chardonnay
  • San Joaquin: March 2 in Chardonnay

M = missing data - no substitution values were available
P = missing data substituted with values from previous day
S1 = missing data substituted with values from CARUTHERS-01.P
S2 = missing data substituted with values from FIREBAUGH/ALISO-01.P
S3 = missing data substituted with values from LOCKEFORD-01.P
E = index was calcuated using previously substituted data

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
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