|Trueman, C -|
Submitted to: Canadian Journal of Plant Pathology
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2012
Publication Date: November 1, 2012
Citation: Trueman, C.L., Hanson, L.E. 2012. The influence of soil moisture and Rhizoctonia solani anastomosis and intraspecific group on the incidence of damping-off and the incidence and severity of Rhizoctonia crown and root rot in sugar beet. Canadian Journal of Plant Pathology. 34(2):321-322. Technical Abstract: Rhizoctonia crown and root rot (Rhizoctonia solani) reduces plant stands, sugar quality and yield in sugar beet. To evaluate the influence of R. solani anastomosis (AG) and intraspecific groups and soil moisture on disease incidence and severity, a field trial was established in Ridgetown, Ontario, Canada in 2011 using the susceptible beet variety 'Crystal 824'. Four moisture treatments (rain-fed and drip irrigation once, twice or three times per week) and three R. solani isolates identified as AG-2-2 IIIB, AG-2-2 IV, and AG-4 were included. Plant stand declined 30 percent more in soil inoculated with AG2-2 IIIB than AG-2-2 IV or AG-4. There were no differences among moisture treatments and no interaction among R. solani isolate and moisture treatments. Disease incidence was higher in beets irrigated with water once per week than in beets not irrigated or irrigated two times per week 64 days after seeding (DAS) but not 96 and 137 DAS, and there were no differences in disease severity among these treatments. Disease incidence and severity for AG-2-2 IIIB were higher than AG-2-2 IV and AG-4 on all assessment dates. Beet weight was lower in plots inoculated with AG-2-2 IIIB than AG-2-2 IV or AG-4 at 137 DAS and there were no differences among moisture treatments on this date. Preliminary results suggest that AG-2-2 IIIB is more aggressive at both the seedling and mature beet stages than AG-4 and AG-2-2 IV regardless of the number of irrigation events.