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CDFA Releases Draft Regulation for Red Blotch Testing in Nursery Program

CDFA Grapevine Regulations Working Group Discusses Sampling Protocols
by Ted Rieger
January 29, 2016

The California Department of Food and Agriculture (CDFA) has released draft regulatory language to add Grapevine red blotch-associated virus (GRBaV), the pathogen for Red Blotch Disease, to the list of viruses that are required for testing of vine material under the California Grapevine Registration and Certification Program. The draft regulations were posted today, January 29, by the Office of Administrative Law, beginning the 45-day public comment period. Comments can be submitted in writing by 5:00 p.m. March 14. Information on where to submit comments is found in the “Notice of Proposed Rulemaking” posted at

The website includes the text of the proposed regulation and the “Initial Statement of Reasons.” No public hearing on the draft regulation is currently scheduled, but any member of the public can request a public hearing up to 15 days before the end of the 45-day comment period. CDFA can adopt the proposed regulation at the end of the 45-day comment period if no substantial changes to the text are made based on comments received. If changes are made to the draft regulation, an additional 15-day period for public comment will be extended before adoption.

CDFA received a written request to review program regulations in 2014 due to concerns about the potential presence of GRBaV in certified nursery stock sold in California, in addition to other program concerns. CDFA held regional meetings for industry input in California’s major grape growing regions beginning in spring 2015. The CDFA Grapevine Regulations Working Group, an advisory committee of 15 grape industry representatives was formed in 2015 to review and revise the program regulations.

Working Group Reviews Sampling/Testing Protocols

The working group met January 26 in Sacramento to review proposed sampling plans and protocols for GRBaV, and proposed protocols for Grapevine leafroll-associated viruses, Grapevine fanleaf virus, and tomato ringspot virus that are already tested under the program.

A presentation on GRBaV and leafroll virus sampling and testing was given by Kari Arnold, UC Davis graduate student in the Department of Plant Pathology who has been studying virus incidence and spread in vineyards with Dr. Neil McRoberts. Both viruses act similarly in the field, aggregating in clusters within a vineyard block, with patches of occurrence that form outward from random focal points of infected vines. Arnold and McRoberts proposed a sampling method designed to detect for disease incidence within 1% in a sampled block. There are 2,100 acres of increase blocks for certified nurseries in California broken down by age as follows: 42% are 5 years old or younger, 30% were planted in the 1990s, 17% were planted from 2000-2009, 10% were planted in the 1980s, and 1% were planted in the 1970s.

Joshua Kress, supervisor of the CDFA Nursery, Seed and Cotton Program, based in Sacramento, said CDFA plans to begin using the suggested sampling method for GRBaV and leafroll viruses beginning this fall. CDFA is in the process of upgrading its lab and is purchasing new equipment to perform real-time polymerase chain reaction (PCR) analysis to begin using it to test for GRBaV this fall. Kress said he hopes to have CDFA program staff receive training on sample collection, handling and testing from UCD Foundation Plant Services (FPS) that has extensive experience with state-of-the-art virus testing technology and methods.

Frequency of Testing Discussed

Under current CDFA regulations, increase blocks are only required to be tested at least once every five years, although CDFA staff do visual onsite inspections of increase blocks annually. Several working group members suggested CDFA’s sampling frequency should be increased. Garrett Buckland of Premiere Viticultural Services in Napa said, “For me to have confidence in the material, the frequency of sampling needs to be bumped up.” Kress said testing every 5 years is a minimum, but CDFA can test more often.

John Duarte of Duarte Nursery also believes the 5-year testing cycle is inadequate, and he suggested adding a traceability component to the program with a tag on each vine sold that lists its propagation history by time and location to provide growers more transparency on the origins and cleanliness of vine material.

Kress said CDFA has authority to investigate and trace back a vine’s history when it tests positive for a virus, and CDFA staff will also investigate when it receives notification from a grower who detects virus in a vine soon after planting, but CDFA is rarely notified. Kress said, “We need to make sure growers know who to contact when they have a problem with nursery material after planting,” noting they can contact CDFA, their county ag commissioner or a Cooperative Extension farm advisor to begin looking into the situation. This also raised the issue of improving data collection, the possibility of creating a database for nursery stock with vine history and traceability, and reporting when viruses are detected in commercial vineyards to determine whether the virus came from the nursery material or from the location where the vine was planted.

Other issues and possible regulation changes raised at the working group meeting included: defining what “certification” means in terms of the level or risk to the grower when buying material (perhaps 1% or less chance of virus present), increasing the frequency of onsite inspections of increase blocks by CDFA staff and the timing of inspections based on seasonal symptoms, and standards for suspending/cancelling certification of vines and nursery blocks. Another point made is that grapevine buyers and the industry must be educated to understand that CDFA certification is not a guarantee that all grapevines purchased from a certified nursery are 100% clean.

Program Overview and Background

The Grapevine Registration and Certification Program was started in 1956 and program regulations were most recently revised in 2010. The program is voluntary, with 31 California nurseries participating in 2014 that managed 73 registered increase blocks. Participants apply to be in the program and pay fees for approval, and for regular inspection and testing of grapevine nursery blocks.

FPS at UC Davis is the source of Foundation block certified material made available to nurseries for propagation in increase blocks. FPS has been testing Foundation block vine materials for GRBaV since 2013 and is following Protocol 2010 standards for vine testing and propagation established under the National Clean Plant Network--protocols more stringent than the CDFA program. Many California nurseries are voluntarily testing vine material for GRBaV and have upgraded practices in response to industry concerns. Many nurseries test a higher percentage of vines than CDFA is required to test under the state program.
Since the program is voluntary, regulatory changes would not completely eliminate the sale of possibly diseased material by non-participating nurseries, or the spread of unclean material by growers who take cuttings to propagate and plant material from older vineyards that may be untested.

Regulatory changes may involve several phases of rulemakings to address higher priority issues first, and allow the working group more time to review other changes that may require more analysis. Information about program revisions and meetings, a copy of the current program regulations, and a link to sign-up for e-mail notifications of updates, can be found at:

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