Strausbaugh, C.A., Panella, L.W. 2016. Beet curly top resistance in USDA-ARS plant introduction lines, 2015

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. In order to identify novel sources of curly top resistance, thirty-one Plant Introduction (PI) Lines were screened in a disease nursery in 2015. The lines were arranged in a randomized complete block design with three replications. A curly top epiphytotic was created by releasing approximately 6 viruliferous beet leafhoppers per plant at the four- to six-leaf growth stage on 24 Jun. Foliar symptoms were evaluated on 13 and 20 Jul using a scale of 0-9 (0 = healthy and 9 = dead) in a continuous manner. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was moderately severe with good symptom development in the susceptible check. Seven of the PIs were not significantly different from the resistant checks based on the overall visual symptom rating. These promising lines will be retested and, if resistance is confirmed, they will be incorporated into the USDA-ARS sugar beet germplasm improvement program as potentially novel sources of resistance to BCTV