Good Fruit Grower

November 2012

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Grapes tackles trunk diseases Research project CAT scan technology to be used to look R for disease infection on the inside of grapevines and trees. by Melissa Hansen esearchers will use nearly $1.8 million in grant money to develop new detection, extension, and research tools for managing wood-canker diseases of grapes and nut crops. Wood-canker diseases are a leading cause of vineyard and orchard removal in many parts of the country. The research project was one of 14 projects funded in October by the U.S. Department of Agriculture's Specialty Crop Research Initiative authorized under the now expired 2008 Farm Bill. A total of $46 million was approved for the SCRI projects. This is the first multicrop project to tackle trunk diseases. Several trunk diseases affect all three of the crops involved in the study—grapes, almonds, and pista- chios. For grape growers, the project aims to stem losses of yield and longevity of the vineyard from grapevine trunk diseases, the primary ones being Eutypa, Esca, and Botryosphaeria. Dr. Kendra Baumgartner, plant patholo- gist for USDA, heads the research. She is stationed at the Agricultural Research Service facility in Davis, California. Research objectives are to develop detection technologies, identify sources of disease resistance, and encourage adoption of preventative practices. Wood-canker diseases Wood-canker diseases are problems in many grape growing regions due to their detrimental effect on yield and the life of the vineyard, Baumgartner said in a phone interview with Good Fruit Grower. Symptoms of wood- canker diseases include dead spurs, arms, and cordons. Eventually, the vine dies due to canker formation in the vascular tissue. "Wood-canker diseases are difficult, because the most obvious symptom of rotted, brown wood is inside the 100 YEARS Because we offer the QUALITY you expect and deserve! Kendra Baumgartner heads the research. vine and you can't see it unless you cut into the trunk or cordon," Baumgartner said. "Sometimes, growers will notice some shoot dieback or that shoots aren't pushing out in the spring. Or they may cut into a specific spur or cordon that doesn't look right to see if something's going on. But that's not an efficient way to look for disease," she said, adding that growers may inadvertently cut into healthy wood. Symptoms often don't show up in vineyards until sev- eral years after infection, typically when the grapevines "A smart-phone app could be valuable in getting growers in the habit of considering wood-canker diseases." —Kendra Baumgartner are seven years or older. Detection usually comes much too late to control the diseases, both for growers and researchers, she said. Moreover, wood-canker diseases are not just grower problems. "There have been a lot of accusations of nurs- eries selling infected plant material. But is that due to poor treatment and neglect of the disease in the field, or because there aren't any standards for wood-canker diseases for nurseries to follow?" she asked. Early detection A key goal of the project is early detection. The research team will pioneer the use of a high-powered type of X-ray, similar to a CAT scan, to look inside the grapevine for changes in the woody stem. The specialized equipment is located at the Lawrence Berkeley National Laboratory in Berkeley, California. The high-resolution technique was used in an SCRI project studying water stress in grapevines. "If we can use the same technique, we can learn about the development of wood-canker diseases inside the plant," she said, adding that whole plants from the greenhouse used in their research could be scanned. The technique could also help researchers learn how resistant cultivars respond to the infection. The research team plans to develop early detection Asian & European Pear trees are still available 100 Years at Newcastle, Ca 800-675-6075 ORDER NOW! 34 NOVEMBER 2012 GOOD FRUIT GROWER tools for diagnostic labs, nurseries, and growers that would sample healthy leaves in the early stage of infec- tion. By combining advanced molecular and imaging techniques to identify the molecular signature, they hope to develop a DNA-based technology that uses green tis- sue in detecting the molecular signature. Such a test using leaves would be more convenient, less destructive, and could be used by nurseries to detect the early stage of infection and limit planting of contaminated nursery stock.

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