Powdery Mildew in Grapes alert

The beginning of the 2024 growing season is set up for a major powdery mildew outbreak. Heavy Powdery Mildew infections during the 2023 growing season left plenty of cleistothecia to over winter in San Joaquin Valley vineyards. Rain during budbreak and now less than 2 weeks into the growing season and the Grape Powdery Mildew Risk Assessment Index is already showing a high risk for powdery mildew spread.  It would be highly advisable to work with your pest management crew to make sure that your vineyard is well protected at the start of this growing season. You can continue to track the Grape Powdery Mildew Risk Assessment Index for the entire season through this UC IPM webpage: https://ipm.ucanr.edu/weather/grape-powdery-mildew-risk-assessment-index/