Clean grapevines – The first and most important step in virus control

Authors: MARTIN, ROBERT

Submitted to: Oregon Wine Research Institute
Publication Type: Popular Publication
Publication Acceptance Date: 3/24/2018
Publication Date: 4/2/2018
Citation: Martin, R.R. 2018. Clean grapevines – The first and most important step in virus control. Oregon Wine Research Institute. Vine to Wine March 2018.

Interpretive Summary: Certification is not a guarantee that plants are free of virus, but rather that the starting material has been fully tested for ‘targeted’ pathogens, usually viruses, bacteria and phytoplasmas, that cause diseases. Once testing is completed, plant propagation is performed using a system of best management practices (BMPs) to minimize the risk of virus infection, and these BMPs are combined with some level of virus testing at the various stages of propagation. Certification programs are managed by State Departments of Agriculture, and therefore each state may have different requirements that nurseries need to meet to produce ‘certified grapevines’. Thus, certification can mean different things depending on where the plants were produced. Over the past two years there has been an effort to harmonize the grapevine certification programs and quarantines in Washington, Oregon and Idaho. This effort is being led Vicky Scharlau, Executive Director of the Washington Wine Industry Foundation, and funded by a grant from USDA Animal and Plant Health and Inspection Service (APHIS). The project includes regulatory staff from the three State Departments of Agriculture, industry members, nursery representatives, and scientists. The process is near completion and there should be a common grapevine certification program for the Pacific Northwest in the near future. There are several caveats that growers need to be aware of: 1. The new certification program will require that all grapevines coming into the three states originate from certification programs recognized by the State Department of Agriculture; 2. Certification is voluntary and therefore not all nurseries are selling certified grapevines; 3. The harmonized certification programs do not require that grapevines sold in-state are from certified nurseries; and 4. For grafted grapevines the rootstock and scion must be certified for the plant to be considered certified, certified rootstock brought into the state, grafted with uncertified scion wood does not result in a certified plant.

Technical Abstract: More than 70 virus and virus-like agents are known to infect grapevines worldwide and relatively few are of major importance in the Pacific Northwest. This is due in a large part to quarantine and certification programs that have resulted in elimination of most of these viruses from planting materials. Once identified, Grapevine Red Blotch Virus (GRBV) was added to the list of pathogens in most certification programs. Certification programs are managed by State Departments of Agriculture and therefore each state may have different requirements that nurseries need to meet to produce ‘certified grapevines’. Thus, certification can mean different things depending on where the plants were produced. Over the past two years there has been an effort to harmonize the grapevine certification programs and quarantines in Washington, Oregon and Idaho. This effort is funded by a grant from USDA-APHIS and led by Vicky Scharlau, Executive Director - Washington Wine Industry Foundation. The project includes regulatory staff from the three State Departments of Agriculture, industry members, nurseries and scientists. The process is near completion and there should be a common grapevine certification program for the Pacific Northwest in the near future. There are several caveats that growers need to be aware of: 1. The new certification program will require all grapevines coming into the three states be from certification programs recognized by the State Department of Agriculture; 2. Certification is voluntary and therefore not all nurseries are selling certified grapevines; 3. The harmonized certification programs do not require that grapevines sold in-state are from certified nurseries; and 4. For grafted grapevines the rootstock and scion must be certified for the plant to be considered certified, for example, certified rootstock brought into the state and grafted with uncertified scion wood does not result in a certified plant.