November 14, 2012 | 11:05 AM
At last week's viticulture fair in Napa nearly every nursery had a sign out that read, "YES! We have vines."
Following are the Napa Valley Grapegrowers recommendations for sourcing clean plant material:
- When purchasing grapevines, it is prudent to do your homework about the plant material you desire to purchase and the nurseries who sell it. Whenever possible it is best to buy plants certified by California Grapevine Registration and Certification Program. Certified grapevines are one of the best bets when purchasing grapevines though it does not guarantee virus free material. When buying grapevines it is important to ask questions and learn as much as possible about the plant material and the nursery selling the material.
- Research nurseries and their operations before settling on a nursery to purchase plant material. Ask your colleagues about their experiences with different nurseries.
- Establish a relationship with the nursery. Visit the nursery and learn about their operations. See the blocks where your plant material is coming from. When possible, your visit should coincide with the development of visual symptoms for plant diseases. Many viruses do not cause visual symptoms in the plant until the fall.
- Buy plant material certified through the California Grapevine Registration and Certification Program; both rootstocks and scion wood selections. Buying certified material does not guarantee that plants will be virus free, but buying certified plant material can bring down the risk of virus infection.
- If field selection of budwood is desired for grafting a vineyard it is important to determine the disease status of the plant material. There is inherent risk in using budwood propagated from existing vineyards. If using field selected wood, judicious work needs to be done. Marking of vines that appear to be visually clean may not insure clean plant material. Clean appearing vines need to be tested with a laboratory for viruses before using. If you desire to use a field selection work with FPS to have the material tested and propagated through their plant material program.
- Determine the age and history of the source block for your plant material. Recently released FPS material is less likely to be diseased.
- When possible, buy material from primary increase blocks only.
- Inspect historic testing results and request testing protocols. How many plants are tested per block? How frequently? If the material hasn’t been tested recently, ask for samplers of the plant material and send it out yourself for testing at a reputable laboratory.
- Avoid buying plant material that is brokered. Nurseries sometime contract outside growers to grow plant material for them. If you must buy brokered materials, visit the site and find out the history of the plant material.
- Avoid buying plant material from secondary increase blocks. Buying from secondary increase blocks may increase the chances of receiving infested material.
- Determine when your vines were grown. Avoid vines that didn’t sell and were held over from a previous season in cold storage.
- Ask the nursery if it is possible to see vineyards planted with the same plant material to observe how the vineyard is doing.
- 12. While most nurseries clearly understand the need for “clean” rootstocks and scions, you may also consider hiring a consultant to assist in evaluating grafting material and finished vines.
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