Influence of Rhizoctonia-Bacterial Root Rot Complex on Storability of Sugarbeet

A Rhizoctonia-bacterial root rot complex can lead to yield loss in the field but rots also have the potential to cause sucrose loss in storage. Thus, studies were conducted to investigate if combining sugarbeet roots suffering from this complex with healthy roots would compromise the ability of the healthy roots to retain sucrose. Over a three year period, root samples from three commercial cultivars were compared in storage as a healthy (eight healthy roots) or mixed (eight healthy roots + one rotted root) treatment inside an outdoor storage pile. The experiment was arranged as a split block (healthy in one half of block and mixed in the other) with the whole blocks arranged in a ran domized complete block design with four replications. Treatments were sampled in December, January, and February and evaluated for discolored and frozen root area, weight loss, and sucrose reduction and recovery. When comparing the healthy to the mixed treatment over the nine year x sampling date combinations, the Wilcoxon signed-rank test indicated the median change for discoloration (7% increase), frozen area (14% increase), sucrose loss (5% loss), and recoverable sucrose (689 kg/ha less or 8% reduction) were signifi cantly different from zero ( P = 0.008, 0.031, 0.007, and 0.008, respectively). These data indicate that the Rhi zoctonia-bacterial root rot complex can negatively af fect neighboring healthy roots in storage leading to additional sucrose losses.