ARS | Publication request: Cultivar Selection for Sugar Beet Root Rot Resistance

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: June 4, 2010
Publication Date: June 11, 2010
Citation: Strausbaugh, C.A., Eujayl, I.A., Foote, P. 2010. Cultivar Selection for Sugar Beet Root Rot Resistance. Phytopathology. 100:S123.

Technical Abstract: Fungal and bacterial root rots in sugar beet caused by Rhizoctonia solani (Rs) and Leuconostoc mesenteroides subsp. dextranicum (Lm) can lead to root yield losses greater than 50%. To reduce the impact of these root rots on sucrose loss in the field, storage, and factories, studies were conducted to establish a faster and more accurate screening method. In 2009, 22 commercial cultivars were grown in a commercial field and mechanically harvested, and then inoculated. In each root a cork borer hole at the widest portion of the root was inoculated with Rs and another with Lm, while a third hole was inoculated with both (RsLm). The roots were then incubated in the greenhouse for 3 weeks out of direct sunlight, cross sectioned, and evaluated for rot. The study was repeated with roots that had been stored for 60 days. All roots suffered some rot with the Rs or the RsLm inoculations and the most susceptible cultivar had 3.9 and 2.8 times more rot than the most resistant cultivar, respectively. Only 15% of the roots developed rot with the Lm inoculation. Similar rot results for all three inoculations were obtained with stored roots. With the RsLm inoculation, cultivar ranking at harvest and after storage were correlated (r = 0.6608, P = 0.0008). The RsLm inoculation may prove to be a faster and more precise method to screen for bacterial rot resistance but screening for fungal rot resistance will likely need to be done using other methods.