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PD/GWSS Board Asked to Study Red Blotch, Brown Marmorated Stink Bug

industry representatives who want the Board to designate red blotch as a pest for board funding and research
by Roger Lansing
January 28, 2014

Responding to recent letters from two different regional winegrape grower groups who want research funds spent to study grapevine red blotch-association virus (GRBaV), and the brown marmorated stink bug (BMSB), the California Department of Food and Agriculture (CDFA) Pierce’s Disease (PD)/Glassy-Winged Sharpshooter (GWSS) Board discussed the two pests, its policy for designating other pests and diseases for study, and possible future direction at its January 27 meeting in Sacramento.

A letter to PD Board chair Drew Johnson from Napa County grower Jim Frisinger, of Frisinger Vineyard, dated January 9, 2014, stated: “On behalf of the Napa County Winegrape Pest and Disease Control District Board of Directors, I am writing to request the PD/GWSS Board designate Grapevine red blotch-associated virus (GRBaV) a serious pest of winegrapes. As representatives of the local winegrape industry, our Board recognizes the serious threat of this disease to the sustainability of our industry due to the direct impacts on fruit quality and grapevine health.”

The letter suggested, “Funds should be allocated immediately to allow researchers to investigate the role of GRBaV in red blotch disease, monitor statewide distribution, incidence and spread, improve detection techniques, determine rootstock and variety-specific impacts and physiological effect of the virus on the vine, evaluate the efficacy of microshoot tip culture for virus elimination and explore potential mitigation strategies.” The letter also noted that the Pest District Board had granted $50,000 to University of California researchers for a current study of insect vectors for GRBaV.

Johnson said he’s also received other recent letters from industry representatives who want the Board to designate red blotch as a pest for board funding and research. In 2013, the PD Board evaluated GRBaV for designation and took a vote at its June 21 meeting that resulted in a 6 to 6 tie of members present, resulting in no action. This was an unsatisfactory outcome for some PD Board members, and some believe it sends the wrong message to the industry about the Board’s process to designate other pests.

The PD/GWSS Board received authorization following 2009 legislation and a 2010 grower referendum (to renew the Board) to use assessment funds for research and outreach on other serious pests and diseases of winegrapes, as long as such funding does not interfere with PD/GWSS research and control efforts. To date, the European Grapevine Moth (EGVM) is the only other pest to receive designation by the Board. The Board allocated funds for outreach activities that assisted with successful control efforts, but no funds are currently budgeted for EGVM.

Lake County Growers Concerned About BMSB
Lake County Winegrape Commission (LCWC) president Debra Sommerfield signed a letter dated December 2, 2013 to CDFA secretary Karen Ross stating, “On behalf of the Lake County Winegrape Commission, I am writing to ask your department and the Pierce’s Disease Control Program (PDCP) to consider giving high priority to research proposals related to the management of the Brown Marmorated Stink Bug given its potential widespread impacts to California agriculture.” The LCWC voted unanimously to send the letter, that also expressed concerns about large numbers of the BMSB in Sacramento, and in the Northern California cities of Chico and Yuba City. (See January 22, 2014 article at

LCWC board director Broc Zoller of Zoller Vineyards grows winegrapes, pears and walnuts and has been a pest control advisor to pear and grape growers in Lake County since 1972. Zoller attended the January 27 PD Board meeting on behalf of the LCWC and said, “We’re here to introduce this subject to you and we’re hoping researchers will apply for funding from the grape industry to study this pest in California.” He acknowledged the BMSB is not currently known to be in Lake County, but he has first-hand experience with a similar pest, the consperse stink bug, in pear orchards. “The BMSB produces more generations than the consperse stink bug, it overwinters in buildings, it has a huge host range, and it will be a pest for the entire state,” Zoller said. Based on BMSB spread and damage in other areas of the U.S., Zoller observed, “People have underestimated what this pest will do.” He added, “Although we don’t know the extent to which it will be a pest in grapes, the sooner we get moving on this, the better off we’ll be.”

Moving Forward

CDFA PDCP statewide coordinator Bob Wynn said, “These types of requests for designation warrant much more information and discussion on the characteristics and potential impacts of the pest or disease, and a discussion of financial requirements to address the problem.” Johnson suggested the Designation Committee should improve its process to give the full Board more information before it votes. “The Committee should provide more information on why we should add a pest and what we should do to address it by coming back to the Board with a full package and plan with suggested research and funding,” Johnson said.

Other Board members pointed out that the ability to address other pests and diseases was a selling point to many growers during the previous legislation and referendum to renew the Board for five years, and some believe more pests should be addressed to benefit more growers.

After discussion, the Board suggested several steps moving forward to better handle the designation of other pests. These include: adding more members to the Board’s “Other Pest or Disease Designation Committee,” meet to clarify and improve the process for designating a pest, involve more public industry members and pest experts in Designation Committee meetings, and better educate all Board members on pests and diseases considered for designation.

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