Viticulture Extension Update:  Raising Trunk Disease Awareness

Dr. Patty Skinkis, Viticulture Extension Specialist & Associate Professor

There has been an increase in the number of reported cases of stunted vine growth and potential trunk disease this spring in the Willamette Valley. The symptoms ranged from delayed bud break to lagging shoot growth compared to healthy blocks, and in some cases led to shoots with distorted and almost tattered-looking leaves. The symptoms looked different than the typical culprits of herbicide drift, frost damage, rust/bud mite feeding, or micronutrient deficiency. Upon closer inspection by sawing into cordons and trunks, significant cankers (dead areas within the vine trunk) were found, and this suggested the potential cause of the limited shoot growth. Although visual symptoms suggested trunk disease, samples were submitted to OSU Plant Clinic to confirm which disease organisms may be causing the damage.

Knowing what trunk disease organisms are present is helpful in understanding next steps for managing the disease. Dr. Melodie Putnam, OSU Plant Clinic Director, summarized the importance of identifying the disease-causing organisms and provides visual examples of trunk disease symptoms in a seminar archived online here. Trunk disease has become more of a “hot topic” in recent years both nationally and internationally. In 2015, Dr. Jose Urbez Torres visited OSU and growers in the north Willamette Valley and southern Oregon to share his expertise and research about trunk diseases in California and British Columbia. His archived seminar is available online here. Research on trunk diseases of grapevines is currently being led by Dr. Kendra Baumgartner, a USDA-ARS plant pathologist from Davis, CA. The work is funded by a federal grant and is aimed at understanding both basic and applied aspects of managing trunk diseases in grapevines and other tree fruit and nut crops. You can learn more about the research here.

Grapevine trunk diseases don’t lead to immediate vine decline. The vine symptoms that are being expressed this spring are likely due to infection years ago, and the vineyards are just now showing the symptoms due to some prior vine stress. The two record breaking yield and heat/drought vintages of 2014 and 2015 may have led to more nutrient and/or water stress that could lead to poor nutrient or carbohydrate storages for early spring growth. The research team on the federal trunk disease grant are working to understand how water stress impacts the disease.

Please see the links below for more information.

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