|Swisher Grimm, Kylie
|Cooper, William - Rodney
|GORMAN, CHRISTOPHER - Washington State University
|CROWDER, DAVID - Washington State University
|WOHLEB, CARRIE - Washington State University
Submitted to: Carrot Country
Publication Type: Trade Journal
Publication Acceptance Date: 1/20/2023
Publication Date: 5/23/2023
Citation: Swisher Grimm, K.D., Angelella, G.M., Cooper, W.R., Gorman, C., Crowder, D., Wohleb, C. 2023. Beet leafhopper associated pathogens in the Columbia Basin of Washington. Carrot Country. 31(2):8-11.
Interpretive Summary: The beet leafhopper is known to vector three pathogens that can cause serious economic damage to a variety of different crops in the northwest United States, including potato, bean, sugar beet, and carrot. USDA-ARS scientists from Prosser and Wapato, Washington, worked with scientists from Washington State University to assess pathogen occurrence in a small vegetable research plot and in a region-wide survey of beet leafhoppers collected from commercial potato and other vegetable or seed fields. Preliminary results from the small plot study indicate that beet leafhopper pathogen occurrence does not correlate to pathogen occurrence in the plant. In the region-wide survey, levels of Beet curly top virus in beet leafhoppers were consistently high, levels of Spiroplasma citri were low and BLTVA phytoplasma levels peaked mid-growing season. Beet curly top virus and BLTVA phytoplasma levels varied between geographical regions within the Columbia Basin. These results, and future confirmation, should help growers make more informed integrated pest management decisions regarding timing and number of applications for control of the beet leafhopper.
Technical Abstract: In the Columbia Basin of Washington and Oregon, the beet leafhopper is known to vector three pathogens to vegetable and seed crops including Beet curly top virus (BCTV), Beet leafhopper transmitted virescence agent (BLTVA) phytoplasma, and Spiroplasma citri. There are currently no treatments that prevent or manage the pathogens, so growers manage the beet leafhopper by removing weedy hosts, and by applying insecticides to their crops or the weedy hosts. Information on pathogen distribution among different crops, and on seasonal beet leafhopper population dynamics and associated pathogen prevalence, can help growers assess the potential for damage to their crops and aid them in their integrated pest management decisions. New insect extraction and molecular diagnostic methods were developed to obtain pathogen prevalence data in beet leafhoppers collected in 2022. Results showed consistently high levels of BCTV and low levels of S. citri over the 22-week season, with BLTVA levels peaking in mid-July. When pathogen prevalence was assessed by plant host, rates of BCTV were higher from beet leafhoppers collected from vegetable and seed fields as compared to potato. Average BCTV pathogen prevalence was lower in the southern Columbia Basin, moderate in the northern Columbia Basin, and highest in the central regions. While BLTVA pathogen prevalence peaked at different weeks in July among the regions, the highest peak rates were at 40-41% in early to mid-July in the southern regions and the lowest peak rates were at 17 and 21% later in July in the northern regions. This information and that gained in future years, in addition to knowledge gained from field or greenhouse trials that explore pathogen dynamics across different crops and beet leafhopper movement in the landscape, should enable growers to improve management of the economically important beet leafhopper-associated pathogens.