Evaluation location: North Dakota, United States
A commercial field site near St. Thomas (Pembina County) in northeastern North Dakota was selected to evaluate Beta germplasm accessions for potential resistance to SBRM feeding injury. The experiment was planted on 6 June, 2013. No planting-time or postemergence insecticide protection was applied to any plots. Individual treatment plots were single rows that were 28 ft (8.5 m) long and spaced 55.9 cm (22 inches) apart. Experimental design was a randomized complete block with four replications of 36 treatments. Treatments included 30 accessions of B. vulgaris maritima that were obtained from the NPGS Beta collection, courtesy of the USDA-ARS Western Regional Plant Introduction Station (Pullman, WA). Six additional entries (i.e., ACH-817, PI-540563, PI-605413, PI-608437, PI-658654, and Yellow) were included for comparative purposes. The commercial hybrid entry, ACH-817, which has been confirmed as susceptible to SBRM feeding injury in previous testing, was used as the susceptible control. Larval feeding injury was assessed on up to ten sugarbeet roots per plot and rated in accordance with a 0 to 9 scale (0 = no damage and 9 = 75% or more of root surface blackened with feeding scars or a dead plant) on 20 August. Sugarbeet root maggot fly activity was relatively high in the plot area, and peaked on 19 June at 167 flies per stake per day. Overall levels of SBRM feeding injury were low compared to most previous years of testing. The lowest SBRM feeding injury in the test (i.e., 1.77 on the 0 to 9 rating scale) was recorded for PI-658654 (F1024).