Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 29, 2012
Publication Date: July 11, 2012
Citation: Strausbaugh, C.A., Wenninger, E.J., Eujayl, I.A. 2012. Management of severe curly top in sugar beet with insecticides. Plant Disease. 96:1159-1164. Interpretive Summary: Curly top in the semiarid production areas of the United States is caused by one of three Curtovirus species (BCTV, BMCTV, and BSCTV) and 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 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 clothianidin was established as the most effective management tool to supplement host resistance. Initial studies under low to moderate natural curly top pressure indicated root yields could be increased by approximately 20% using the clothianidin seed treatment. Current studies under severe curly top pressure indicate root yields could be increased by 55 to 95% with several second generation neonicotinoid seed treatments when compared to untreated check plots. The current studies also have shown these treatments are very effective even 50 to 55 days after planting under severe (6 viruliferous beet leafhoppers per plant) curly top pressure.
Technical Abstract: Curly top caused by Curtovirus species is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. The insecticide seed treatment Poncho Beta has proven to be effective in controlling curly top in sugar beet, but was only evaluated under light to moderate disease pressure. Thus, the insecticide seed treatments Poncho Beta, NipsIt INSIDE, and Cruiser Force were evaluated under severe curly top pressure (6 viruliferous beet leafhoppers per plant) in field studies during the 2010 and 2011 growing seasons on two commercial sugar beet cultivars. In addition, the foliar insecticides Movento, Provado, and Scorpion were also evaluated. The seed treatments and Scorpion reduced curly top symptoms by 33 to 41% (P <0.0001) and increased root yield by 55 to 95% (P <0.0001), sucrose content by 6.5 to 7.2% (P = 0.0013 to <0.0001), and estimated recoverable sucrose by 58 to 96% (P <0.0001) when compared to the untreated check. Movento and Provado did not improve control beyond that provided by Poncho Beta. Even under severe disease pressure 50 to 55 days after planting, neonicotinoid seed treatments can effectively reduce curly top, increase yield, and help protect against early season insect pest pressure.