Evaluation of sugar beet germplasm for rhizomania and storage rot resistance in Idaho, 2012

Rhizomania in the field and fungal root rot in storage can both lead to significant sucrose losses in sugar beet roots. In an effort to reduce these losses, sugarbeet germplasm developed by the USDA-ARS Kimberly sugarbeet program was evaluated for resistance to both these disease problems. Nine sugarbeet lines and four check cultivars were arranged in a randomized complete block design with six replications and grown in a field known to be infested with Beet necrotic yellow vein virus (BNYVV), the causal agent of rhizomania. The plants were evaluated for foliar symptoms in July, August, and September. Plots were harvested in October, roots were evaluated for rhizomania root symptoms, and roots from each plot were also placed in a commercial indoor storage building (set point 34 F) until 7 February (127 days in storage). Most experimental entries were different from the susceptible check for both rhizomania variables. Based on both foliar and root ratings, the most BNYVV resistant entry, K944-EMS-9, was not significantly different from the commercial resistant checks. When the germplasm were evaluated for rot in storage, the primary fungal growth was an Athelia-like Basidiomycete (Mycologia 104:70-78), but Botrytis sp., Penicillium sp., and Phoma sp. were also frequently present. All Kimberly germplasm performed significantly better than the BNYVV resistant and susceptible checks in storage. These preliminary data would suggest that resistance to BNYVV is different from resistance to storage rot since there were no significant differences observed between commercial checks for root rot in storage. The performance of some of the Kimberly germplasm may help identify genetic backgrounds for additional sources of resistance to both BNYVV and storage rots