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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #325763
Title: Length of efficacy for control of curly top in sugar beet with seed foliar insecticides

Author
item Strausbaugh, Carl
item WENNINGER, ERIK - University Of Idaho
item Eujayl, Imad

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2016
Publication Date: 6/8/2016
Publication URL: http://handle.nal.usda.gov/10113/62630
Citation: Strausbaugh, C.A., Wenninger, E.J., Eujayl, I.A. 2016. Length of efficacy for control of curly top in sugar beet with seed foliar insecticides. Plant Disease. 100(7):1364-1370.

Interpretive Summary: Curly top in the semiarid sugar beet production areas of the United States is caused by Beet Curly Top Virus (BCTV), which is vectored by the beet leafhopper. Resistant sugar beet cultivars became available in the 1930s prior to which curly top almost eliminated the sugar beet industry in the western United States. However, resistance is typically low to intermediate in commercial sugar beet cultivars and has a tendency to be associated with lower yield potential. Thus, alternative control measures are needed to alleviate curly top losses. A number of in-furrow, foliar, and seed treatment insecticides have been investigated but the neonicotinoid seed treatment Poncho Beta was established as the most effective management tool to supplement host resistance along with the foliar insecticide Asana. However, the length of efficacy of these insecticides is poorly understood, so a series of field experiments was conducted. Poncho Beta and Asana decreased visual curly top ratings an average of 41% and 24%, respectively compared to the untreated check. Poncho Beta and Asana increased root yields an average of 39% and 32%, respectively compared to the untreated check. When considering estimated recoverable sucrose (ERS), the Poncho Beta treatments increased yield by 75% compared to the untreated check over the first two weeks. By week 10 only the Poncho Beta + Asana treatment consistently led to increases in ERS, while the influence of increasing host resistance may have made other treatments more difficult to separate. When considering all variables among all weeks and years, there was a tendency for the insecticides in the Poncho Beta + Asana treatment to complement each other to improve efficacy.

Technical Abstract: Curly top in sugar beet caused by Beet curly top virus (BCTV) is an important yield limiting disease that can be reduced via neonicotinoid and pyrethroid insecticides. However the length of efficacy of these insecticides is poorly understood, so a series of field experiments was conducted with the seed treatment Poncho Beta (60 g a.i. clothianidin + 8 g a.i. beta-cyfluthrin/100,000 seed) and foliar treatment Asana (55.48 g a.i. esfenvalerate/ha). A series of four experiments were conducted in 2014 and repeated in 2015 with four treatments (untreated check, Poncho Beta, Asana, and Poncho Beta + Asana) which were arranged in a randomized complete block design with 8 replications. To evaluate efficacy, viruliferous (contain BCTV strains) beet leafhoppers were released at different times for each experiment – either 8, 9, 10, or 11weeks after planting (1 to 4 weeks after Asana application). Over both years, in 30 of 32 comparisons for treatments with Poncho Beta and 14 of 16 comparisons for Asana, visual curly top ratings were decreased an average of 41% and 24%, respectively compared to the untreated check. Over both years, in 8 of 8 comparisons for treatments with Poncho Beta and 6 of 8 comparisons for Asana, root yields were increased an average of 39% and 32%, respectively compared to the untreated check. When considering estimated recoverable sucrose (ERS) over both years, the Poncho Beta treatments increased yield by 75% compared to the untreated check over the first two weeks. By week 10 only the Poncho Beta + Asana treatment consistently led to increases in ERS, while the influence of increasing host resistance may have made other treatments more difficult to separate. When considering all variables among all weeks and years, there was a tendency for the insecticides in the Poncho Beta + Asana treatment to complement each other to improve efficacy.