Issue link: https://read.dmtmag.com/i/84143
F thought were clean of virus, now we're finding are not. That's because at the time, we couldn't detect all of the viruses out there with the technology that we had." Also, virus could have moved into the original foundation block from vectors, he said. Old mother blocks that have become contaminated are being phased out, and thousands of vines have already been removed. Many grapevine diseases are difficult to diagnose based on visual symptoms. Some cultivars don't show any signs of the disease, while others show a host of differ- ent symptoms for the same disease. Symptoms can also mimic nutritional and other problems. "We just can't do visuals for the mother blocks anymore," said James Susaimuthu of the Clean Plant Center. Starting in 2012 and continuing through next year, all cer- tified grape nursery registered (mother) blocks in Washington will be retested to confirm their virus-free status. The testing is being paid for by a $250,000 specialty crop block grant awarded to the Washing- ton Wine Industry Foundation. In addi- tion to the testing, the grant will support a statewide clean plant campaign to Washington State University postdoctorate student Femi Alabi demonstrates how grape tissue is analyzed for virus. heighten industry awareness of grapevine diseases. Bring in samples WSU virologist Dr. Naidu Rayapati urges growers to bring suspicious-looking samples of grape leaves and petioles to his laboratory for free analysis. Rayapati, who works closely with state officials, researchers, and industry to stay on top of grapevine diseases in the state, can use information from the samples in his educational program. "All test results brought in by growers will remain confidential," he said, stress- ing that he prefers samples to go to him rather than to commercial laboratories for diagnosis. Not only does he offer testing free of charge to the grower, but he knows that the appropriate test will be con- ducted, and test samples will be properly run and validated. or questions about grapevine diseases or testing, contact Dr. Naidu Rayapati at (509) 786-9215 or e-mail him at: naidu@wsu.edu. The WSU lab uses molecular diagnos- tic methods to detect grape viruses. Lab technicians have established RT-PCR (reverse transcription polymerase chain reaction) assays to detect diseases, but technicians also use the ELISA (enzyme- linked immunosorbent assay) method to complement the RT-PCR results. Rayapati explained that each machine uses a dif- ferent technique, so running both types of tests can improve the chances of finding single and mixed viruses. Collecting samples is relatively easy, Rayapati said. Growers should collect mature leaves with petioles from both sides of the vine to account for uneven distribution of the virus within a plant. Place leaf samples in a zip-top plastic bag and store them in a refrigerator or under cold conditions until transported to the lab. Samples can be packed with cold packs and shipped for overnight delivery. "Be careful to keep the samples from sitting out in the hot sun when collecting them," he said. Identify the samples and document the vine location within the vineyard in case additional samples need to be tested. • Continued strong demand for vines N orthwest grape growers thinking about planting vines in the near future are advised to plan well ahead. Strong demand for grapevines that's coming from California is impacting grape nurseries around the country, including Washington State. Kevin Judkins of Inland Desert Nursery in Benton City, Washington, Growers who haven't planned ahead may have to compromise gave a tour of his family's certified grape nursery to grape growers and winemak- ers during a summer field day sponsored by the Washington Association of Wine Grape Growers. During the tour, which focused on the importance of clean, virus-free plants, members learned what goes into state grape quarantine and certification programs and how commercial nurseries handle certified plant material. "The demand for grapevines right now is planting choices. by Melissa Hansen insane," said Judkins, who joined his father's nurs- ery business several years ago. "California is taking all the budwood that they can find. We're even get- ting calls from California nurseries for self-rooted plants, which they don't typically plant, because they are so desperate to source plant material." Kevin's father, Tom Judkins, founded Inland Desert in 1960. Tom planted some of the first registered vinifera blocks in the state for propagation and sold certified vines. Inland Desert has grown significantly in the last few years, Kevin said, han- dling upwards of three million self-rooted vines annually and sending them to nearly every state and Canada. "Our goal as a nursery is to be full service and compete with the biggest and best in California," he said, adding that being able to sell certified vines that are also certified free of crown gall disease is an advan- tage when dealing with growers from other U.S. regions. "The foundation block at Prosser where we source our registered mother block vines is recognized as the cleanest program in the world, and the treatment to keep crown gall out of the vines has gained attention everywhere," Kevin said. The Benton City nursery recently expanded its nursery to more than 100 acres www.goodfruit.com Certification process Plan ahead Kevin warned that growers who don't plan ahead will find plant material in short supply for the next few years and will likely have to make sacrifices, like accepting noncertified material or taking a different clone than they wanted. California wine industry officials are projecting tight grape supplies in the next three years, and some say the wine grape supply is on the cusp of a shortage. New plantings in California have been on the rise the last three years, and planting hasn't let up yet. For a variety of reasons, including a growing number of wine drinkers and increased wine sales, wine grape plantings in California haven't kept up with demand. Nat DiBuduo, president of Allied Grape Growers, California's largest wine grape marketing cooperative, projected earlier this year that the state's shortfall could reach 600,000 tons by 2014. • GOOD FRUIT GROWER OCTOBER 2012 37 of registered rootstock and scion propagative blocks to increase the supply of certified material. Greenhouse facilities allow Inland Desert to use mist green tip propagation to produce potted vines. They can also produce bench-grafted vines. Certified plant material is one generation from registered nursery blocks that are regulated and annually inspected by the Washington State Department of Agriculture. Vines grown in registered blocks come directly from cuttings of the foundation block maintained by the Clean Plant Center-Northwest Grapes and housed at Washington State University's Prosser research station. Each vine in the registered block can be tracked to a single vine in the foundation block. Certified vines are the best option for growers who are concerned about long- term sustainability, profitability, and want clean, virus-free and true-to-type vines, Kevin said. "They come directly from the registered block and are regulated by state officials. If it is a step beyond that, you can't call the material certified." Because there are limitations on the amount of certified plant material avail- able during planting booms, certified plants are the first to sell out. Kevin said that if growers have to resort to noncertified material, the key is to get it tested. Photo by Melissa hansen