|Swisher Grimm, Kylie
|WATERS, TIM - Washington State University Extension Service
|WOHLEB, CARRIE - Washington State University Extension Service
Submitted to: Potato Progress
Publication Type: Trade Journal
Publication Acceptance Date: 5/13/2019
Publication Date: 5/13/2019
Citation: Swisher Grimm, K.D., Waters, T., Wohleb, C. 2019. Studies on the mysterious foliar damage in Northwest potato in recent years. Potato Progress. 19:1-5.
Interpretive Summary: For the past few seasons mysterious foliar damage has been observed in potato fields across the Columbia Basin of Washington and Oregon. Researchers at the USDA-ARS Temperate Tree Fruit and Vegetable Research Unit in Prosser, WA, in collaboration with Washington State University scientists conducted greenhouse and laboratory research to determine if a pathogen was associated with these symptoms. Greenhouse grafting of diseased tissue to healthy potato plants did not show transmission of the mysterious foliar symptoms to the healthy plant, and molecular diagnostic analyses did not identify a common pathogen in the symptomatic field samples. These results suggest the cause of the mysterious foliar symptoms in the Columbia Basin is not pathogenic in nature.
Technical Abstract: In the 2017 and 2018 growing seasons, plants with disease-like symptoms appeared in July and August across the Columbia Basin of Washington and Oregon. Symptoms included leaf distortion with crinkled, warped leaves often found with small holes, purpling of upper terminal leaves, and stem damage seen as blisters and necrotic lesions. To determine if a pathogen was associated with these mysterious disease-like symptoms, symptomatic tissue was subjected to molecular diagnostic and greenhouse grafting analyses, and field-grown tubers were analyzed for emergence of symptomatic tissue in the greenhouse. The inability to detect graft transmission of the mysterious disease-like symptoms from field samples in the Columbia Basin in 2017 and 2018 provides strong evidence that the disease-like symptoms are not caused by a pathogen. In support of this, molecular diagnostic techniques used to detect common bacterial and viral pathogens did not identify a pathogen that correlated with the observed field symptoms, and commercial tubers collected from symptomatic plants did not produce symptomatic foliage when grown in the greenhouse.