By Darin Allred, Ph.D., Technical Sales Support, Chemtura AgroSolutions
Year-in and year-out, you must deal with powdery mildew. Success depends on a consistent, well-developed, season-long management plan that’s founded on good management principles and has the flexibility to adjust to ever-changing vineyard conditions.
While the exact steps and timing of actions may vary by vineyard and area, the best plans have the following components in common.
• Understand the disease. To control the disease, begin by understanding how powdery mildew behaves under various conditions and management situations. This model from the University of California offers helpful insight into how to improve management decisions based on the pathogen life cycle and how it reacts to environmental situations.
• Obey the weather. Use weather forecasts to help determine the best application times and identify times of potentially higher disease pressure. Websites like this weather index can help.
• Choose your chemistry class. You have options when it comes to controlling this disease. The three most commonly used fungicides used on grapes include sterol inhibitors, like Viticure® fungicide, that inhibit the development of cell walls in the target organism, strobilurins and inorganics. Strobilurins interfere with energy production and cell respiration to prevent spore germination in fungi and inhibit mitochondrial electron transport. Inorganic compounds prevent fungi from attaching to plant surfaces.
• Avoid resistance. You also have a responsibility to manage your control tools properly. Rotate product chemistries during the season to prevent resistance and ensure long-term efficacy of powdery mildew fungicides. Avoid back-to-back applications of the same class of chemistry. Viticure has a distinct advantage in that it is an imidazole which means it is not cross resistant to most other sterol inhibitors, and therefore aids in resistance management. Keep in mind that rotation brings out the benefits of each chemical group to deliver effective disease control while managing resistance development.
• The label is the law. As with any control product, fungicides are most effective when applied at labeled rates and directed spray intervals. Therefore, don’t skimp on applications or extend timing of sprays—follow label directions at all times. Also be sure to get good spray coverage during applications by practicing proper equipment maintenance.
Watch this video for more insight into managing powdery mildew in your vineyard this season.
And visit with your PCA or Chemtura AgroSolutions™ representative for additional advice and information to ensure a successful season:
• Mike Ansolabehere, Southern San Joaquin Valley: (661) 304-3023; email Mike.Ansolabehere@Chemtura.com
• Matt Loftus, Central San Joaquin Valley: (559) 960-1112; email Matthew.Loftus@Chemtura.com
• Carson Conover, North Central California: (530) 906-1504; email Carson.Conover@Chemtura.com
• Eric Leer, North Central California: (209) 531-6478; email
• Eduardo Garcia, California Coast: (805) 625-4101 or email Eduardo.Garcia@Chemtura.com