Evaluation location: North Dakota, United States
Several Beta germplasm accessions were assessed for potential resistance to sugarbeet root maggot (SBRM) feeding injury in a field trial near St. Thomas, ND. Plots were planted on 11 May, 2007, and none of the treatments received chemical insecticide protection. Individual treatment plots were single, 28-ft (8.5 m) long rows that were spaced 22 inches (55.9 cm) apart. Experimental design was a randomized complete block with four replications of 35 treatments. Treatments included 30 accessions of B. vulgaris maritima obtained from the NPGS Beta collection, courtesy of the USDA-ARS Western Regional Plant Introduction Station (Pullman, WA). Five additional entries (i.e., PI-605413, PI-608437, PI-658654, Beta 2084, and FC704) were included for comparative purposes. Sugarbeet root maggot fly activity timing was normal for the area, and activity peaked 12 June at a moderate rate of 65 flies per trap per day. 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 17 August. Root maggot feeding injury levels observed for most entries were also mostly moderate when compared to most years. The lowest levels of SBRM feeding injury were incurred by roots of PI-658654 (F1024) plants, for which the average feeding injury rating was 0.85. Entries that were not significantly different from PI-658654 with respect to SBRM feeding injury incurred included FC704, PI-608437 (F1016), and PI-605413 (F1015), for which the average root ratings were 1.13, 1.40, and 1.60, respectively. Other entries that sustained relatively low levels of SBRM feeding injury (mean < 3.0) included Beta 2084, PI-518377, PI-546389, PI-540565, PI-540633, and PI-540666. PI-518373, PI-562599, PI-251042, FC704, PI-232888, and PI-608437 (F1016).