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FPS Research Shows Red Blotch in Calif. Since 1940?

FPS Meeting Provides Update on CDFA Grapevine Certification Program Revision Plan
by Ted Rieger
November 21, 2014

Based on recent tests performed with dead grapevine leaf material on file in the University of California Davis (UCD) Plant Herbarium, UCD Foundation Plant Services (FPS) director Deborah Golino stated, “Red blotch has been present in the Sonoma County winegrape growing area for at least 74 years.” Golino announced the finding at the annual FPS meeting held November 20 in Davis to update nursery industry representatives on FPS activities.

The study used currently available laboratory testing technology for Grapevine Red Blotch-associated Virus (GLRaV) on 56 different grapevine specimens placed in the UCD herbarium from 1937-1950. Only one specimen tested positive--a sample of the cultivar Early Burgundy collected by UCD viticulture professor emeritus Dr. Harold Olmo from a Sonoma County vineyard in 1940.

The finding provides evidence for what researchers have been saying since red blotch and GRBaV were formally identified as a disease and virus in 2012. As Golino reiterated, “Red blotch has been with us a long time, but we now have identified it as an individual virus, and we now have the tools to detect it.”

In a discussion at the meeting regarding another recent study by UCD and FPS staff, it was noted that there have been no positive detections to date of GRBaV in wild grapevines sampled in locations near vineyards where red blotch is present, however, GRBaV has been detected in blackberry plants near vineyards. Although research is currently underway to identify possible vectors for GRBaV, none have been identified by researchers to date in California vineyards.

Expressing her hypothesis about several grapevine viruses that are sometimes found together, Golino said, “I believe that red blotch, leaf roll and fanleaf viruses all co-evolved with Vitis vinifera in Europe.”
Revision of CDFA Grapevine Certification Program.

Nick Condos, director of the California Department of Food and Agriculture (CDFA) Plant Health and Pest Prevention Services Program, updated meeting attendees on plans to review and potentially revise CDFA’s Grapevine Registration and Certification Program. The revision, announced in October at a meeting of the CDFA Pierce’s Disease/Glassy-winged Sharpshooter Board, came about after informal meetings earlier this year between grape growers, nursery representatives and CDFA staff, initially over concerns about red blotch and the fact that GRBaV is not included in the certification program’s list of grapevine viruses required for testing of grapevine material to be certified as “clean” nursery stock sold in California.

Condos said CDFA plans to begin scoping meetings to take public comment for the revision plan, perhaps held at several locations in California, beginning in early 2015, a change from CDFA’s previously announced plan to begin meetings in December. Condos noted that the grapevine certification program was started in the 1950s, and the program’s last modification began in 2008 and took about two years to complete.

In addition to red blotch, the informal discussions earlier this year identified other possible issues about the program to address, such as overall program management, frequency and timing of CDFA inspections at nurseries, and traceability of plant material. As Condos explained, ‘It seems obvious that getting red blotch into the program as soon as possible is at the top of the list of proposed changes.” But there is also interest in analyzing the program in general, and Condos said, “We may move forward to deliver a program that better meets the needs of the industry today.” He said CDFA currently has a small staff overseeing the program, and there may be interest in exploring other options to how the program currently looks and functions, but this will take more time to analyze. Since these different issues will take different time frames to move forward, Condos suggested the issues could proceed at different rates and there could be multiple rulemakings to achieve more timely updates.

see previous coverage:

CDFA Plans Review of Grapevine Certification Program

Red Blotch Disease and the Virus Status of CDFA-certified Grapevine Stock

The Impact of Grapevine Red Blotch Virus


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