Volume 11 Issue 8
The Pacific Northwest berry research and extension community met a second time to discuss the blueberry plant health issue affecting several fields in western Washington, Oregon, and British Columbia. Symptoms observed in affected plants (primarily ‘Liberty’ and ‘Bluecrop’) included dieback of 1-year old wood, reduced vegetative/lateral shoot emergence, lesions on vegetative leaves, and floral bud or flower blight. The pattern observed across the region does not match freeze or frost damage. Pathology assays led by Dr. Chakradhar Mattupali indicated that there were no pathogens consistently being isolated from affected tissues, and pseudomonas was found only on a few of the samples. Dieback continued to progress after bloom but did not extend to older wood, based on observations made to date in western Washington. Affected growers are experiencing yield loss as a result of this plant health problem, but at this stage, we believe the damage will be restricted to this year given it has not extended to older wood. The potential causes of this plant health problem remain speculative and could be environmental (e.g., heat, cold, and/or high moisture), viral (e.g., scorch virus, which certain assays cannot detect due to viral genome diversity), or an interaction between environmental factors and viral infection. Unfortunately, the complexity of the plant health problem makes it nearly impossible to confidently diagnose. Our recommendation is for growers to follow best management practices for irrigation and nutrient management, to remove affected tissue and prune hard during winter pruning to stimulate regrowth, and to test for viruses if viruses are suspected. Below are labs that can conduct virus testing. Carefully follow sample collection and submission protocols. If virus is detected, follow best management practices outlined in the PNW handbook (link: https://pnwhandbooks.org/plantdisease/host-disease/blueberry-vaccinium-corymbosum-virus-diseases#:~:text=Cause%20At%20least%20six%20viruses,virus%2C%20and%20Tomato%20ringspot%20virus) and/or consult with local area specialists.
Prepared by: Lisa DeVetter, Chakradhar Mattupalli, Dimitre Mallov, Eric Gerbrandt, David Bryla, Tom Walters, Julie Pond, Jason Myer, Virginia Stockwell, Carolyn Tesdale, Siva Sabaratnam, Kelly Ivors, Jenny Glass, and Wei Yang