|Swisher Grimm, Kylie
|GORMAN, CHRISTOPHER - Washington State University
|CROWDER, DAVID - Washington State University
|WOHLEB, CARRIE - Washington State University
Submitted to: Potato Country USA
Publication Type: Trade Journal
Publication Acceptance Date: 1/20/2023
Publication Date: 4/20/2023
Citation: Swisher Grimm, K.D., Gorman, C., Crowder, D., Wohleb, C. 2023. Potato purple top in the Columbia Basin: Beet leafhopper and BLTVA pathogen prevalence. Potato Country USA. May-June 2023;6-7.
Interpretive Summary: Since 2002, potato purple top disease has been a persistent problem in the Columbia Basin of Washington and Oregon, caused by the beet leafhopper transmitted BLTVA phytoplasma pathogen. Researchers at the USDA-ARS laboratory in Prosser, Washington, worked in collaboration with Washington State University scientists to obtain weekly BLTVA pathogen data from beet leafhoppers captured across the Columbia Basin of Washington State, in order to disseminate pathogen data to commercial growers for incorporation into their pest management programs. Across the region in 2022, BLTVA rates peaked in mid-July, with the highest levels seen in the lower Columbia Basin. This data was incorporated into the Washington State University Potato Decision Aid System, and it is anticipated that data obtained in subsequent years will identify important pathogen trends and provide commercial growers with valuable information that can impact their integrated pest management decisions.
Technical Abstract: Purple top disease of potato has been a persistent problem in the Columbia Basin of Washington and Oregon since it was first observed in the region in 2002. Potato plants show purpling and curling of upper leaf tissue, aerial tuber formation and plant decline, ultimately leading to decreased tuber yield. The causal agent of this disease was identified as the Beet leafhopper transmitted virescence agent (BLTVA) phytoplasma, which is transmitted to potato and other crops by the beet leafhopper. Currently, there are no BLTVA-specific treatments, so control of potato purple top disease is done through managing the beet leafhopper vector. Understanding the threat of BLTVA in beet leafhoppers captured throughout the region could enable growers to better time pesticide applications or even reduce the number of applications used each season. Season-long data obtained in 2022 identified a peak in BLTVA pathogen prevalence in beet leafhoppers in mid-July. The month of July also saw the highest number of beet leafhoppers collected and tested. BLTVA pathogen prevalence peaked at different weeks in July across the region, with the highest rates (40-41%) found in the southern regions and the lowest rates (17-21%) in the northern regions. Results from this single year of data indicate that the BLTVA pathogen may be a higher threat to crops grown in the southern region of the Columbia Basin. While BLTVA and potato purple top disease has been a persistent problem in the Columbia Basin for the past 20 years, improving the overall understanding of pathogen presence throughout the region could help reduce the economic impact of this disease on potato production.