Experimental sugar beet cultivars evaluated for resistance to rhizomania and storability in Idaho, 2010

Twenty-seven experimental sugar beet cultivars and five commercial check cultivars were evaluated in a sprinkler-irrigated sugar beet field near Kimberly, ID where sugar beet were grown in 2009. The field trial was conducted in a field that contained Portneuf silt loam soil and relied on natural infection for rhizomania development. The plots were planted on 26 Apr 10 to a density of 142,560 seeds/A, and thinned to 47,520 plants/A on 12 Jun. Plots were four rows (22-in. row spacing) and 24 ft long. The experimental design was a randomized complete block design with four replications per cultivar. The crop was managed according to standard cultural practices. The plants were mechanically topped and the center two rows were collected with a mechanical harvester on 18-19 Oct. At harvest the roots were evaluated for rhizomania (Rz rating) using a scale of 0-9 (0 = healthy and 9 = dead). The percent sucrose at harvest was established based on two eight-root samples from each plot. The samples were submitted to the Amalgamated Tare Lab (determined percent sucrose, conductivity, nitrates, and tare). At harvest, eight roots per plot were also placed in a mesh onion bag, weighed, and placed in an indoor commercial sugar beet storage facility in Paul, ID on 19 Oct set to hold 35°F. On 7 Feb 11 roots were retrieved after 112 days in storage and evaluated for weight, percentage of surface area covered by rot or microbial growth, and percent sucrose (via gas chromatography). Only samples from the same plots were compared, when establishing percent reduction in sucrose at harvest versus storage. Data were analyzed in SAS (Ver. 9.2) using the generalized linear mixed models procedure (Proc GLIMMIX), and least squares means (? = 0.05) were used for mean comparisons. Root rots and other disease problems other than rhizomania were not evident in the plot area. Rhizomania was uniform based on foliar and root symptoms. There were significant differences among cultivars for all variables, except surface root rot. B-103 was susceptible to rhizomania as expected, but C-31 had a higher foliar reading than expected. Root yield averaged 33.3 tons/A which was higher than Idaho’s average of 31.0 tons/A (USDA-National Ag. Stat. Service). By the end of the storage season, weight loss ranged from 6.0 to 11.4% and sucrose losses ranged from 19 to 33%. Thus, improving storability in sugar beet cultivars to reduce sucrose losses could have considerable economic benefit.