Controlling powdery mildew is a process. Experienced grape growers know that early-season treatment is a good start but that doesn’t mean they can back down the rest of the year. Staying ahead of the disease, following label recommendations and maintaining sound IPM practices are key to managing this disease.
Staying ahead of powdery mildew means applying the right materials at the right times for the vineyard. The Powdery Mildew Index created by Dr. Doug Gubler and his team at the University of California – Davis is one tool helping PCAs and growers determine what fungicides to use during different stages of the powdery mildew life cycle for best control. For more on the Powdery Mildew Index, click here.
Despite the array of management tools and fungicides available today, Sonoma, Calif.-based premium wine-grape grower Mike Saini still sees people skimping on their sprays. “When the grape price per ton falls, vineyard owners can be tempted to cut costs by using less fungicide,” says Saini.
He urges grape growers to consider the long-term consequences of incomplete powdery mildew control. “Cutting rates and stretching intervals seems to save money in the short term, but long term, you’ll have a higher concentration and incidence of powdery mildew overall,” Saini says.
Resistance development and decreased product efficacy are two potential dangers vineyard owners face if they choose to skimp on powdery mildew management measures, according to Saini. “Even if the disease appears to be controlled with less fungicide, diminished control may not kill all the spores, allowing some to get inside the vine wood, damaging the vine and future production.”
Even a single season of poor powdery mildew management means PCAs and growers will have to play catch up by applying higher fungicide rates at shorter intervals to get control, Saini cautions. “Powdery mildew eradication costs more than prevention because you use higher rates of stronger materials more often,” he says. “Spending a little more this season on powdery mildew control saves you money in coming seasons.”
Mike Saini and Kerman, Calif.,-based PCA and grape grower Rod Yraceburu share their secrets to successful powdery mildew control here.