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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
08/01/2015
Disease pressure Pathogen status
Amador
(map)
Based on bud break, March 26, in Zinfandel,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Amador_Eagle-01.P, EAG1, Screaming Eagle 0 (E) low is present
Amador_Renwood-01.P, REN1, Renwood Winery 20 (E) low is present
Calaveras
(map)
Based on bud break, March 20, in Chardonnay,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Ironstone-01.P, IRN1, Ironstone M    
El Dorado
(map)
Based on bud break, March 9, 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 (E) high reproduces every 5 days
Lava_Cap-02.P, LAV2, Lava Cap 90 (E) high reproduces every 5 days
Fresno
(map)
Based on bud break, March 6, in Thompson Seedless,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
CARUTHERS-01.P, CAR 40 (E) intermediate reproduces every 15 days
Del_Rey/Fowler-01.P, DELF 20 (E) low is present
EASTON-01.P, EAS 40 (E) intermediate reproduces every 15 days
KERMAN-01.P, KER 40 (E) intermediate reproduces every 15 days
KINGSBURG-01.P, KNG 50 (E) intermediate reproduces every 15 days
Kearney_Ag_Ctr-01.P, KAC 20 (E) low is present
Laton_North-01.P, LATN 40 (S1) intermediate reproduces every 15 days
SAND_RANCH-01.P, SR1 30 (E) intermediate reproduces every 15 days
Madera
(map)
Based on bud break, March 6, in Thompson Seedless,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
FIREBAUGH/ALISO-01.P, FRBA 50 (E) intermediate reproduces every 15 days
Madera_North-01.P, MADN 50 (S2) intermediate reproduces every 15 days
San Joaquin
(map)
Based on bud break, February 28, in Chardonnay,
you may need to adjust for other cultivars that emerge earlier than the indicated date.
Collegeville-02.P, COL2 0 (E) low is present
LIVE_OAK-01.P, LIV 0 (S3) low is present
LOCKEFORD-01.P, LOC 0 (E) low is present
LODI-01.P, LOD 0 low is present
PETERS-01.P, PET 0 low is present

*   Bud break based on farm advisor countywide vineyard surveys:

  • Fresno: March 6 in Thompson Seedless
  • Madera: March 6 in Thompson Seedless
  • Amador: March 26 in Zinfandel
  • Calaveras: March 20 in Chardonnay
  • El Dorado: March 9 in Chardonnay
  • San Joaquin: February 28 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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