Evaluation location: Idaho, United States
Thirty Plant Introductions (PIs) from the USDA-ARS National Plant Germplasm System (NPGS) (Garden Beet, Sugar Beet, Leaf Beet, Fodder Beet, and wild beet) were evaluated for resistance to the beet curly top virus in an artificially inoculated nursery, managed by the Beet Sugar Development Foundation (BSDF) in Kimberly, ID. The field was planted on 11 through 12 June. Planting was late to maximize the number of viruliferous leafhoppers available to transfer to the sugarbeets while they are in the 8- to 10-leaf stage. Plots were 12 ft long, two-rows with 22 in between rows and replicated twice. After the beets emerged, plots were trimmed to 8 ft long, thinned to one foot between beets, and cultivated. Viruliferous leafhoppers were released on 11 and 12 July to cause an artificial epiphytotic. One week before the leafhoppers were released in the nursery, they had been transferred onto curly top-infested beets to assure that they were viruliferous when placed in the field. Uniform infection was achieved by placing approximately 100,000 leaf hoppers uniformly throughout the field, and then spreading the leafhoppers daily for the next week by dragging a 12-foot tarp across the field. The field was sprayed two weeks after release to kill the leafhoppers. The summer was very hot and dry and the epiphytotic extremely severe, and ratings were taken August 31.