Influence of Sugarbeet Tillage Systems on the Rhizoctonia-Bacterial Root Rot Complex

The Rhizoctonia-bacterial root rot complex in sugarbeet caused by Rhizoctonia solani and Leuconostoc mesenteroidescan cause significant yield losses. To investigate the impact of different tillage systems on this complex, field studies were conducted from 2009 to 2011. Split blocks with conventional and strip tillage as main plot treatments were arranged in a randomized complete block design with four replications. Within main plots, there were seven treatments (non-inoculated check and six R. solaniAG-2-2 IIIB strains). Regardless of tillage, the roots responded in a similar manner for fungal rot (conventional 8% versus strip 7%), bacterial rot (26% versus 34%), total rot (33% versus 41%), neighboring roots infected (1.7 roots versus 1.5 roots), distance spread (15.7 cm versus 15.0 cm), and the number of dead plants (12% versus 14%). Strains F517, F521, F551, and F552 always led to the lowest root and sucrose yield. Strip tillage resulted in 6% more root yield in 2009 (P = 0.087), while conventional tillage resulted in 7% and 27% more root yield in 2010 (P= 0.063) and 2011 (P = 0.012), respectively. The tillage systems influenced disease variables in a similar manner, but more studies will be needed to determine their impact on yield.