2012 growth in the vineyards of Fresno County raisin grower Dennis Wilt is a bit behind the same time last year.
Wilt and his wife, Johnell, own D& J Farms at Biola, Calif., and grow 142 acres of Thompson seedless and 30 acres of Zante currants. Some of the vines were planted by his grandfather 97 years ago.
Thompson seedless shoots started pushing normally at the middle of March, he notes. A month later they had reached about 12 to 14 inches in length.
“We had good dormancy and a good start to this season,” he says. “But since then, it seems, we’ve had cold fronts coming through and bringing rain every five or six days, which has slowed things. Normal summer weather would give us a chance to catch up.”
From October until mid-March, Wilt’s vineyards received much less rain than usual — no more than about 1.5 inches total. Over the next month, however, there was another 6.5 inches of rain.
His vineyards escaped the early April frost that hit others in the area, including neighbors on both sides. “One grower, about a mile away, suffered some heavy frost damage,” he says.
Less than a week later, hail fell. “We got a little here,” Wilt says, “but some vineyards really got hammered.”
Wet ground slowed completion of Wilt’s early-season fungicide applications. His first spray included a tank-mix of micronized sulfur to combat powdery mildew, and a copper product to defend against phomopsis.
“Because of the cold weather, phomopsis hasn’t been a problem to this point,” he says. “But, I want to get sulfur on the vines as insurance. I apply it every 7 to 10 days to stay ahead of powdery mildew. If the weather continues wet, I make a second application of copper to treat new growth along with the sulfur. Otherwise, I back off the copper and continue sulfur treatments until veraison.”
This month, Wilt’s field work will include suckering to remove unwanted growth around the vines. Once bloom begins, probably mid-May, he’ll spray gibberellic acid to thin bunches.
“Not all growers do this,” he says. “But, over the years I’ve figured out what works best for me. I’d rather control grape growth that let nature do it.
“Right now, things look good for agriculture in our area,” Wilt says. “The past decade has been tough for raisin growers — now it’s our turn to enjoy some pretty good times.”