Powdery mildew pressure light

Even in the midst of the cool, foggy mornings on the Central Coast, powdery mildew hasn’t necessarily been a problem this year. At least that’s been the situation for Erin Amaral, PCA with Pacific Vineyard Co. in San Luis Obispo, Calif.

“We have the pressure, but we don’t have the mildew,” she says. “We haven’t found it yet. The index has indicated 100 percent pressure, and we have the perfect weather for it.”

Even so, the beast hasn’t reared its ugly head this season. “I don’t know exactly why,” she says. “However, we’re on a good preventative program, and I think we got very good coverage this year.”

Even so, it’s a never-ending battle to keep mildew in check.

“We have a no-sulfur program here on the ranches,” Amaral says. “We rotate through the strobulirins, the DMIs, boscalid, and the newer products. We rotate, rotate, rotate.”

With approximately 2,200 acres to monitor and treat, Pacific stays mostly on a 14-day spray schedule. “We use Gubler’s model to watch our pressure to see when it’s coming up and help us get started,” she says. “But after that we have to stay on a schedule or we’d never get across the vineyards. It would be hard for us to catch up if the disease got out of hand. We actually stretched it this year to 17 days which worked out fine.”

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