By the Chemtura AgroSolutions team of experts
“It’s important to get an early jump on powdery mildew,” says Chuck Ware, PCA with Wilbur-Ellis in Madera, California. “Once it gets started, the disease is difficult to control.”
That’s because disease spores easily overwinter awaiting adequate temperatures and moisture to spring to life and infect plants.
“Even though we’re still in a drought situation, the spores are always present,” notes Ware. “When we get the right temperatures and a little moisture, powdery mildew can take off at any time. It’s something we battle all season long.”
Ware suggests investing in early-season spray treatments to get ahead of powdery mildew, then continuing to spray according to proper timing intervals to suppress it throughout the season.
“I watch the Powdery Mildew Risk Assessment Index from the University of California to assess the threat level and then use every preventive measure available to deal with powdery mildew,” he explains. He begins with an application of wettable sulfur, often combined with copper or a systemic fungicide and builds his program from there, choosing chemistries and tools to deal with the disease and prevent resistance.
When Ware begins to see increased foliage development in vineyards he’s found that Viticure,® a systemic sterol inhibitor fungicide labeled for protective and curative control for powdery mildew, fits into his spraying rotation. It works by inhibiting development of the target organism’s cell walls, without which the organism cannot survive.
“In the area where I work, Viticure fits well at the prebloom and postbloom stages to deal with powdery mildew,” says Ware.
Regular scouting is another way to stay on top of disease pressure. During rapid shoot growth look for flagging (wilting) shoots or shoot tips. If flagging is found, try to determine if it is due to branch and twig borer, Botrytis, or powdery mildew.
Newly emerging shoots displaying malformed foliage, stunting, and a white powdery or dusty appearance indicate an overwintering bud infection by powdery mildew.
Be sure to visit with your PCA or Chemtura AgroSolutions representative for additional ways to ensure a successful season:
• Mike Ansolabehere, Southern San Joaquin Valley: (661) 304-3023 or email Mike.Ansolabehere@Chemtura.com
• Matt Loftus, Central San Joaquin Valley: (559) 960-1112 or email Matthew.Loftus@Chemtura.com
• Eric Leer, North Central California: (209) 531-6478 or email Eric.Leer@Chemtura.com