Evaluation location: North Dakota, United States
A grower-owned field site near St. Thomas, ND was selected to evaluate Beta germplasm accessions for potential resistance to SBRM feeding injury. The experiment was planted on 26 May, 2011. No chemical 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 40 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). Ten additional entries (i.e., Beta 1301, Crystal R761, FC704, PI-182146, PI-504262, PI-540563, PI-605413, PI-608437, PI-658654, and 3JS1217) were included for comparative purposes. Crystal R761, one of the commercial hybrid entries, served 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 11 August. Sugarbeet root maggot fly activity in the area began about two weeks later than normal, and peaked on 28 June at 82 flies per trap per day. This was a moderate level of SBRM fly activity in comparison to most years. Accordingly, SBRM feeding injury in most entries was also somewhat moderate when compared to other years of testing. As a result, statistical differences among entries were relatively infrequent. The lowest SBRM feeding injury in the test (i.e., 1.33 on the 0 to 9 rating scale) was recorded for FC704. Other entries that incurred very low (< 2.0 on the 0 to 9 scale) levels of SBRM feeding injury included PI-518402 and PI-608437 (F1016). These two entries, in addition to FC704, were the only entries that sustained significantly less injury than the susceptible commercial hybrid (i.e., Crystal R761; rating mean = 2.88). Other entries that incurred low levels of feeding injury which were not significantly different from FC704 included Beta 1301 (a commercial hybrid), PI-182146, PI-504262, PI-518403, PI-518423, PI-540580, PI-540639, PI-540590, PI-540688, PI-540693, PI-540697, PI-546401, PI-605413 (F1015), PI-658654 (F1024), and 3JS1217.