Beet curly top virus strains in sugar beets, dry beans, and beet leafhoppers along with vector population dynamics in southern Idaho.
At the request of a sugar beet industry stakeholder, beet leafhopper (BLH) populations in southern Idaho were tracked in four counties during the 2020 and 2021 growing seasons in desert areas and sugar beet and dry bean fields in southern Idaho with yellow sticky cards. Samples were collected on a weekly basis from mid-April through mid-September to assess all leafhoppers for population levels and the presence of Beet curly top virus (BCTV) strains. Crop plants from monitored fields were also assessed for the presence of BCTV strains. Once BLH populations in Elmore Co. began increasing in May, they were present in at least double-digit numbers through most of the summer at all sites both years. However, the BLH numbers at desert sites in other areas were at or near zero. In areas with low BLH desert populations, local weed populations appeared to be the primary source of BLH in crop fields. Preliminary data suggest two haplotypes (based on cytochrome oxidase gene) dominate the BLH population. Over the 22-week collection period, horizontally oriented cards averaged 75% and 51% fewer BLH than vertically oriented cards in 2020 and 2021, respectively. In 2020, 42% of the BLH samples were positive for the BCTV coat protein and Worland was the dominant strain. The phytoplasma, morphotyping, and 2021 BCTV strain identifications are currently a work in progress. Once all data are collected, the project will establish the BCTV strains for which host plant resistance is needed and the time when sugar beets are at highest risk for BCTV infection.