Beet leafhopper and BCTV strain survey

Authors: Strausbaugh, Carl; WENNINGER, ERIK - University Of Idaho

Submitted to: The Sugarbeet
Publication Type: Trade Journal
Publication Acceptance Date: 12/18/2020
Publication Date: 3/22/2021
Citation: Strausbaugh, C.A., Wenninger, E.J. 2021. Beet leafhopper and BCTV strain survey. The Sugarbeet. Research Issue:27.

Interpretive Summary: Screening for resistance to Beet curly top virus (BCTV) in sugar beet suggests that at least some sources of resistance are strain specific. Also, beet leafhopper populations can vary by location and year. Thus, at the request of a sugar beet industry stakeholder, beet leafhopper populations in southern Idaho were tracked during the 2020 growing season in desert areas and sugar beet and dry bean fields in four southern Idaho counties. Beet leafhopper populations in Elmore Co. were present in at least double-digit numbers per sticky card each week at all sites through most of the summer. By late in the summer, beet leafhoppers were also evident in Twin Falls and Bingham Co. some weeks, but they were almost undetectable in Minidoka Co. Vertical card placement was preferable since horizontal placement reduced captures by 75%. Sequencing the cytochrome oxidase gene identified that two haplotypes were dominant within the beet leafhopper population. Data for the BCTV strains found in the beet leafhoppers and plants are not available at this time. Once all data are collected, the project will establish the BCTV strains for which host plant resistance is needed and the best time for when control of beet leafhoppers is necessary.

Technical Abstract: Screening for resistance to Beet curly top virus (BCTV) in sugar beet suggests that at least some sources of resistance are strain specific. Also, beet leafhopper populations can vary by location and year. Thus, at the request of a sugar beet industry stakeholder, beet leafhopper populations in southern Idaho were tracked during the 2020 growing season in desert areas and sugar beet and dry bean fields in four southern Idaho counties. Samples were collected on a weekly basis from May through mid-September to assess all leafhoppers for population levels and the presence of BCTV strains. Crop plants from monitored fields were also assessed for the presence of BCTV strains. Beet leafhopper populations in Elmore Co. were present in at least double-digit numbers through most of the summer at all three sites. However, populations peaked in the Elmore desert (avg. 401 beet leafhoppers per 40 sq. inches) on 20 May, while populations in the bean field peaked in late Jun to mid-Jul (avg. 24) and the sugar beet field on 5 Aug (avg. 69). In the Twin Falls Co. desert, the beet leafhopper populations were low (high was an avg. of 3 in Aug) throughout the season. While the Twin Falls Co. sugar beet field peaked with an average of 27 beet leafhoppers on 22 Jul and the bean field peaked with an average of 4 beet leafhoppers on 15 Jul. In Minidoka Co. only a few beet leafhoppers were collected at all three sites late in the summer. In Bingham Co. beet leafhoppers at the desert and sugar beet sites were almost undetectable through the whole season. However, the Bingham Co. bean field had an average of 23 beet leafhoppers by 26 Aug. Preliminary data suggest two haplotypes (based on cytochrome oxidase gene) dominate the beet leafhopper population. Over the 19-week collection period, the horizontal card averaged 75% fewer beet leafhoppers than the vertical card. The BCTV strain and phytoplasma identification is 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 best time for when control of beet leafhoppers is necessary.