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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
04/23/2017
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 0 n/a no infection
Amador_Renwood-01.P, REN1, Renwood Winery 0 n/a no infection
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 0 n/a no infection
West_Point-01.P, WES1, West Point 0 n/a no infection
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 0 n/a no infection
Gold_Hill-01.P, GLD1, Gold Hill, Saureel Vineyards 0 n/a no infection
Lava_Cap-02.P, LAV2, Lava Cap 0 n/a no infection
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 100 high reproduces every 5 days
Del_Rey/Fowler-01.P, DELF 100 high reproduces every 5 days
EASTON-01.P, EAS 100 high reproduces every 5 days
KERMAN-01.P, KER 30 intermediate reproduces every 15 days
KINGSBURG-01.P, KNG 100 high reproduces every 5 days
Kearney_Ag_Ctr-01.P, KAC 100 high reproduces every 5 days
SAND_RANCH-01.P, SR1 60 high reproduces every 5 days
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 0 n/a no infection
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 30 intermediate reproduces every 15 days
LIVE_OAK-01.P, LIV 0 low is present
LOCKEFORD-01.P, LOC 0 n/a no infection
LODI-01.P, LOD 0 n/a no infection

*   Bud break based on farm advisor countywide vineyard surveys:

  • Fresno: March 9 in Thompson Seedless
  • 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

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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