Dispersal of beet leafhoppers and pine pollen in southern Idaho

Authors: Strausbaugh, Carl; WENNINGER, ERIK - University Of Idaho; Jackson, Laurie; Vincill, Eric

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2024
Publication Date: 9/27/2024
Citation: Strausbaugh, C.A., Wenninger, E.J., Jackson, L.K., Vincill, E.D. 2024. Dispersal of beet leafhoppers and pine pollen in southern Idaho. PhytoFrontiers. https://doi.org/10.1094/PHYTOFR-06-24-0073-SC.
DOI: https://doi.org/10.1094/PHYTOFR-06-24-0073-SC

Interpretive Summary: The management of beet leafhoppers (BLHs) is important for disease control since BLHs can vector important plant pathogens such as curly top viruses and phytoplasmas in southern Idaho. Historical data for southern Idaho suggests that BLH need approximately 130 growing degree days (GDDs) to initiate dispersal and around 382 GDDs until they reach peak dispersal. A recent study in southern Idaho identified large peak dispersal events of BLHs on May 19, 2020 and June 2, 2021 in Elmore County near Mountain Home, Idaho. Historically, BLH are supposed to originate from local areas. However, based on GDDs and dispersal numbers under optimal conditions for Mountain Home, the BLHs likely did not originate from local areas. Data for wind and pine pollen dispersal combined with GDDs for areas known to contain BLH suggest that the BLH could have originated outside the local area and possibly up to 88 to 320 miles away. Five conditions emerge that are necessary for large-long distance BLH dispersal to be successful in southern Idaho: a wind event must occur (22 mph avg. hourly wind speed), dispersal temperature threshold (61 to 64°F) must be met, >130 GDDs must be accumulated to initiate dispersal, daily peak temperatures should reach 75°F, and attractive BLH vegetation such as Russian thistle must be present. Combining wind event forecasts with temperature parameters may make it possible to improve future management plans to provide targeted timely sprays for BLH control.

Technical Abstract: The management of beet leafhoppers (BLHs) is important for disease control since BLHs can vector important plant pathogens such as curly top viruses and phytoplasmas in southern Idaho. Historical data for southern Idaho suggests that BLH need approximately 130 growing degree days (GDDs; 12.8°C base) to initiate dispersal and around 382 GDDs until they reach peak dispersal. A recent study in southern Idaho identified large peak dispersal events of BLHs on May 19, 2020 and June 2, 2021 in Elmore County near Mountain Home, Idaho. Historically, BLH are supposed to originate from local areas. However, based on GDDs and dispersal numbers under optimal conditions for Mountain Home, the BLHs likely did not originate from local areas. Data for wind and pine pollen dispersal combined with GDDs for areas known to contain BLH suggest that the BLH could have originated outside the local area and possibly up to 142 to 515 km away. Five conditions emerge that are necessary for large-long distance BLH dispersal to be successful in southern Idaho: a wind event must occur (35 km/h avg. hourly wind speed), dispersal temperature threshold (16 to 18°C) must be met, >130 GDDs must be accumulated to initiate dispersal, daily peak temperatures should reach 24°C, and attractive BLH vegetation such as Russian thistle must be present. Combining wind event forecasts with temperature parameters in the future may make it possible to provide targeted timely sprays for BLH control.