The Central and Northern San Joaquin Valley grape crops are also slower than usual in developing this year.
Sara Savary, a PCA with Crop Care Associates, Fresno, Calif., estimates the delay at about two weeks. She works with raisin, table and wine grape growers from Fresno County north to the Delta.
“Everything is behind schedule, but the crop isn’t looking too bad,” she says. “I think it will be behind all year. It may catch up a few days, but to make up two weeks would require temperatures so hot that the crop would burn up.”
The unusually cool, wet weather earlier this season resulted in an erratic bloom. While some clusters were in full bloom, others on the same vine had yet to start, Savary says. That could be a problem if the crop doesn’t catch up with the calendar.
The poor weather also caused poor pollination, reducing the cluster berry count.
Savary has also seen varietal differences in pollination, mainly among some European red wine varieties, like Merlot, which didn’t pollinate as well as others because of the cool weather. Cold weather doesn’t cause the problem for Mediterranean varieties.
“Conditions have been very good for powdery mildew development and most growers have tightened up their rotation of fungicides,” Savary says. “Those who are trying to stretch the interval between fungicides to the max will find themselves in trouble. We’re already seeing powdery mildew popping up.”
Fortunately, the rainy weather had not resulted in as much Botrytis as she thought it would — so far, at least. Nor have insect pests or mites posed much a threat for her growers this year.
“A small leafhopper hatch is starting now, but there are so few adults flying around that I’m not sure it will be much of a problem. Mealybugs are about the only thing that seems to be on their same schedule. Usually, they show up with a vengeance around July 4, and it looks like they’ll do the same this year.”