The biology and epidemiology of Pierce's disease, newly defined practices for safe use of sulfur in vineyards, and a system for drying raisins on the vine using traditional raisin trellises are among the half-dozen presentations slated for the 2001 San Joaquin Grape Symposium 8:30 a.m. to 1:30 p.m. Wednesday, Jan. 10, at the C.P.D.E.S. Hall, 172 W. Jefferson Ave., in Easton.
Noted UC Davis plant pathologist Bruce Kirkpatrick will take on the subject of Pierce's disease, an incurable condition fatal to grapevines that is threatening San Joaquin Valley vineyards. The disease is not new to the area, but the recent introduction of glassy-winged sharpshooter, a pest that efficiently transmits the bacteria that causes Pierce's disease, has farmers, lawmakers and scientists concerned about the future of the valley grape industry.
Jerry Prieto, Fresno County Ag Commissioner, will describe new "best management practices" for sulfur use in vineyards, which were recently completed by a task force with representatives from UC Cooperative Extension, ag industry groups, the California Department of Pesticide Regulation, ag commissioners and manufacturers of sulfur.
"We don't want to lose sulfur as a tool," Prieto said. "It is a very safe material but we need to be careful how we're applying it."
The new management practices, which are available in a pamphlet to be distributed at the meeting, make recommendations on time of day to apply sulfur, wind speed conditions at application time, types of equipment to use and other factors.
"We want to encourage farmers to be aware of their surroundings," Prieto said. "If your vineyard is next to a school or other high-traffic area, make applications when school is not in session or when traffic is not high and leave an untreated buffer zone around sensitive areas."
In another session, UC Cooperative Extension viticulture farm advisor Bill Peacock will explain how raisin farmers can use the new dried-on-the-vine (DOV) raisin production technique without investing thousands of dollars in a new trellis system.
"We have completed our first year of research and are very optimistic that the system is practical and feasible, but the research is in its beginning stages," Peacock said.
DOV offers the potential to increase yields and produce high quality, natural, sun-dried raisins while cutting labor costs, reducing vineyard cultivation, and eliminating the need to purchase and burn paper drying trays.
On the downside, DOV raisins take longer to dry. Cool or wet weather some years may mean raisins must finish drying in a dehydrator, increasing production costs and hassle.
Other topics to be covered at the grape symposium are:
Performance of new raisin varieties under comparative DOV trellis and vine training systems
Phomopsis: Disease cycle and potential control measures
Rootstocks for raisin production
Preregistration for the San Joaquin Valley Grape Symposium, including lunch and proceedings, is $20. After Jan. 3 and at the door registration is $25. To register, send name, address and phone number with a check payable to "UC Regents" to: Stephen J. Vasquez, Viticulture Advisor, UC Cooperative Extension, 1720 S. Maple Ave., Fresno, CA 93702. For more information contact Vasquez at (559) 456-7567,