Influence of inoculum levels of Rhizoctonia solani and susceptibility on new potato germplasm

The influence of inoculum levels (10, 15 and 20 of R. solani AG-3) of the isolate CL-58 to Rhizoctonia disease was evaluated by using two potato cultivars (Cardinal and Desiree) and three advanced breeding lines (SH-216-A, TPS-9813 and CIP-393594-61). Evaluation of eyes germination, death of emerging sprouts, incidence and severity of stem and stolon canker, blackscurf and yield (six disease parameters) revealed that as the inoculum level of R. solani AG-3 increased in the soil, there was a significant (P=0.05) increase in all disease parameters measured. Moreover, 20 g inoculum was ascertained as the most effective dose for green house screening. The susceptibility in 14 potato cultivars and advanced breeding lines was investigated by using isolate CL-58 of Rhizoctonia solani anastomosis group 3 (AG-3) under greenhouse conditions. Evaluation 6 disease parameters of each cultivar and advanced breeding ranked Desiree and SH-216-A as susceptible and Cardinal and CIP-393574-61 as resistant (P=0.05).