The quality of plants you choose to grow in your vineyard is important for successful development and/or grafting-over established vineyard blocks. Often concern is placed primarily on getting a certain cultivar (variety), clone, or rootstock quickly, rather than taking the steps necessary to ensure that the plant material is from a sound source. This can lead to vineyards having poor performance in fruit yield and/or quality if its health is compromised by viruses.
The Oregon wine grape industry has long been interested in clean plants—vines propagated from healthy, virus-free sources. However, interest increased after the identification and industry-wide reporting of Grapevine Red Blotch Virus (GRBV). Meanwhile, an effort was underway to improve grapevine quality in the Pacific Northwest. Washington led the charge with Oregon and Idaho to create basic, uniform standards for state grape quarantines to prevent invasive pests and diseases and to ease inter-state movement of plant materials. The result of this effort was updated quarantines and certification programs in each of the three states. The updated Oregon Grape Quarantine went into effect in April 2021 by the Oregon Department of Agriculture (ODA). The new quarantine takes a step-wise approach to limit grapevine importation to virus-tested then certified-only plant material by January 2023. Since September 1, 2021, all vines coming into the state must be propagated from mother vines tested and confirmed free of two important viruses: grapevine leafroll-associated virus 3 (GLRaV- 3) and GRBV. By January 1, 2023, all vines coming into the state will need to be certified.
What does certification mean? Certified plant materials are those that are propagated from a certified source. Nurseries that carry certified plants ensure that they are propagated from mother vines that are evaluated and tested under their state department of agriculture’s certification guidelines. These guidelines include correct cultivar identity (trueness to type), regular visual inspection and testing for important pests and diseases of grapevines, including virus testing and documentation of vine history. At present, California and Washington’s grape plant certification programs are the only two recognized programs accepted by the ODA. Nurseries growing certified stock from other states with grape certification programs (NY and MO) may qualify, if their state’s standards for certification are approved by ODA.
How do I know if plants are certified? Be sure to ask nurseries for cultivars, clones, and rootstocks that are certified before buying plant material. Keep in mind that nurseries often carry both certified and non-certified stock, so making this distinction is critical if you are bringing in plants from outside of Oregon, especially after January 2023. Until then, you may purchase certified or non-certified plant materials, as long as the nursery tests and confirms the mother vines are free of GLRaV-3 and GRBV.
Purchasing plants in-state. The Oregon Grape Quarantine applies to the importation of plants from out- of-state. There is no requirement for plants purchased in-state to be tested for virus or to be certified. While some nurseries in-state may carry certified stock, Oregon’s current grape certification practices do not require virus testing. The ODA is updating the Oregon grape certification guidelines to meet the same rigor as California and Washington. Some local nurseries have expressed interest in producing certified grapevines once the new certification protocols are released. If you wish to purchase plant materials from within Oregon, it is recommended that you only purchase vines from nurseries that confirm that mother vines have been recently tested and found negative for viruses, including GRBV, GLRaV, and Grapevine fanleaf virus (GFLV). Although this is not a requirement by ODA, it is a good practice.
Grafting-over blocks. If you plan to change cultivars in an established block by grafting over to a new cultivar, be sure to consider the health status of the current vineyard and the budwood source vines. Have the current vineyard block tested for viruses and inspect for trunk disease cankers. Also, have the budwood source (for the scions) tested as well. The best time for virus testing is during dormancy. Collect dormant canes and have them tested by an analytical lab known for grapevine virus testing. OSU Extension provides a list of virus testing labs that serve the West Coast.
Planting certified grapevines and/or vines that have been tested and confirmed free of virus will not guarantee that they will remain virus-free during their entire lifespan. New viruses may be identified over time as researchers continue to understand plant pathogens. Viruses may spread by vectors that are present or that move into the region. Therefore, it is important that you stay informed about pests and diseases and take steps to avoid new pest and disease entry locally and regionally. Buying quality grapevine stock is the first step in developing a strong integrated pest management program for a successful vineyard. Read the additional resources below to understand the process that leads to clean and certified plant stock in the US and make note of the specific changes to the Oregon Grape Quarantine. If you have detailed questions about the quarantine, contact ODA. — By Patty Skinkis, Professor & Viticulture Extension Specialist, Oregon State University