- High numbers of sharpshooters are showing up in Sonoma County vineyards this year, including a new one, the Virginia creeper leafhopper. It’s coming Sonoma’s way.
Bud break in Sonoma County’s wine grape vineyards is all but finished. It started with Chardonnay and, depending on site location, such other early varieties as Malbec and Grenache. Cabernet Sauvignon was the last of the major varieties to send out new shoots.
In most cases timing was close to if not a bit behind the normal pace of development, reports Nick Frey, president of the Sonoma County Winegrape Commission.
So far this season, his growers have had to do very little, if any, frost protection. Night time temperatures have been in the high 40s to low 50s.
“The vineyards are growing well and most shoot growth ranges from several inches to as much as 10 inches,” Frey says. “And, we haven’t had rain that would encourage development of botrytis or other fungal diseases.”
Many growers were putting on sulfur, either in a dust or liquid form, on their vines to prevent powdery mildew infection. Others were using oil product for the same purpose. Those seeking longer residual activity also were including a fungicide in their oil treatments.
A higher than normal number of blue-green sharpshooters appeared this spring, following unusually high populations last season, Frey notes. Along with the red-headed sharpshooter and the glassy-winged sharpshooter, the blue-green sharpshooter spreads the bacterium that causes Pierce’s disease.
“We didn’t see much of a spike in Pierce’s disease infections last year,” Frey says. “Hopefully, we won’t see that this year, either.”
Sonoma County growers are watching for the possible arrival of a new insect threat – the Virginia creeper leafhopper. It’s similar in appearance and life cycle to the native western grape leafhopper. However, unlike the western grape leafhopper, the Virginia creeper leafhopper is not well controlled by native parasites. Insecticides will control both leafhopper species in conventional vineyards. However, due to lack of natural controls, the Virginia creeper leafhopper is more difficult to control in organic vineyards where it has caused damage.
Native to the northern Midwest, this pest was found in the northern Sacramento Valley and northern Sierra Foothills in 2008. Most recently it has been detected in Mendocino and Lake counties. “It’s coming our way,” Frey warns.
Despite such concerns, growers remain optimistic about the season ahead of them. Demand for their grapes may have softened a little, following last year’s biggest-ever Sonoma County wine grape crop. However, there are still buyers seeking the grapes, Frey notes.
“After last year’s harvest, a lot more money has been circulating within the ag community this spring than in the last two years,” he says. “That has many growers feeling good.”
On that high note, Frey is departing his post. He’s retiring May 1, 14 years to the day after he accepted that position.
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