By Clint Thompson
A good fungicide spray program will help protect Southeast grape production amid a rainy summer and potential disease buildup.
Phil Brannen, University of Georgia Cooperative Extension fruit disease specialist, highlighted disease management and how much better the grape crop is protected compared to prior years.
“If you have a good spray program, very aggressive, like an every 7-to-10 day spray program to keep something on target for the major diseases, you’ll have pretty good grapes,” Brannen said. “I was up at my Blairsville site (recently), and I didn’t see hardly any diseases at all. That’s because we know what we’re spraying and are spraying it well. Sprays are going out every 7 to 10 days. If you’re spraying well, you should not have any disease.
“You’ve got to make sure you’re putting on materials in a protective fashion and not have days where you’re not covered with fungicides. Also, use the combination of contact materials, like mancozeb or captan, and then add to those the more active materials that are more site specific fungicides for downy mildew and powdery mildew.”
Southeast vineyards are especially vulnerable to downy mildew because of the humid and wet climate during the growing season. Spores can infect within a few hours when the leaves or fruit are wet. Dew counts for sufficient wetness. Brannen has seen firsthand the impact that downy mildew can have on grape production if left untreated.
“I did a downy mildew trial here in Watkinsville, Georgia. I think we started it in April, and we finished a couple of weeks ago, because we had that much downy mildew. For the untreated, we were completely defoliated. That just shows how bad it can be if you don’t have good fungicides,” Brannen said.