Controlling curly top in sugarbeet has been industry priority in the western United States since the 1920s. Curly top is a virus disease that is vectored by the beet leafhopper. If the beet leafhopper moves into commercial fields early in the season, virus is more likely to be transmitted to sugarbeet plants at an early growth stage. However, the plants are more susceptible to the virus at early growth stages. Thus even if the plants contain host resistance, they sustain considerable damage if infected at an early growth stage. In order to supplement host resistance insecticide seed treatments were investigated previously and proven to be effective under low to moderate disease pressure. In the current study under high disease pressure (6 viruliferous beet leafhoppers per plant), the neonicotinoid insecticide seed treatments (clothianidin and thiamethoxam) performed well. Thus the neonicotinoid seed treatments would appear to be a good supplement to host resistance even under high disease pressure
