Abstract
Curly top caused by Beet curly top virus (BCTV) is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. Host resistance is the primary defense against this problem, but resistance in commercial cultivars is only low to intermediate. The neonicotionoid seed treatments currently supplement this resistance to provide early season control. In order to identify other management options seven insecticide treatments were screened in 2023 on a commercial sugar beet cultivar approved for production. The plots were arranged in a randomized complete block design with eight replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the eight-leaf growth stage on 12 June. Foliar symptoms were evaluated on 7 and 25 August using a scale of 0-9 (0 = healthy and 9 = dead). Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was severe with good symptom development in the non-treated check. The three treatments with the Poncho Beta seed treatment provided better control than the other treatments based on foliar ratings, root yield, and estimated recoverable sucrose (ERS). Combining Methyl Jasmonate and Jasmonic Acid foliar treatments with the Poncho Beta seed treatment led to the best root yield and ERS. The Asana foliar check had the next best foliar ratings, root yield, and ERS. All other treatments including the non-treated check were dead at the second foliar rating and had almost no yield or ERS. This data show that sugar beet production in areas with curly top would suffer greatly without the neonicotinoid seed treatments and supplemental foliar treatments. Additional evaluations will need to be conducted with other insecticides if alternatives to the neonicotinoid (Poncho Beta) chemical class are to be identified for curly top control.