Resistance of Sorghum Line CS 621 to Rhizoctonia solani AG1-IA and Other Sorghum Pathogens

Sorghum line CS 621 was evaluated along with other lines and cultivars for resistance to Rhizoctonia sheath blight, tar spot and gray leaf spot for 3 years. CS 621 was consistently resistant to these diseases even under a heavy natural outbreak of tar spot in the breeding nursery. It was also found to be more resistant to Rhizoctonia sheath blight than the resistant lines from Japan during the 1993 to 1994 screening tests. Resistance to Rhizoctonia solani AG1-IA was expressed in the form of reduction in the severity of disease and rate of infection. Evaluation of progenies from crosses involving CS 621 and a susceptible variety, UPL Sg5, indicated that additive and dominant gene effects are important in the expression of quantitative resistance to R. solani. CS 621 could therefore serve as a source of multiple resistance genes in a breeding program for high yield and stability against sorghum diseases.