Screening of New Sugarcane Genotypes for Resistance to Red Rot (glomerella Tucumanensis)

Preliminary investigations in South Africa into determining the resistance of sugarcane varieties to red rot (Glomerella tucumanensis) by means of an inoculation procedure, conducted in 1988-89, showed promise. Results of these trials, together with findings from industry-wide red rot surveys in the late 1980s, were used to provide a preliminary ranking of a number of released varieties. Variety N13 was found to be highly susceptible, whereas N12, N16 and N14 were rated as resistant. Three trials of advanced selections and additional released varieties have since been completed. Most of the released varieties tested were found to be resistant or moderately resistant to red rot. However, 15% of the 93 new genotypes in the final stages of selection, were found to be more susceptible than N13 and were considered too susceptible for further selection. Screening for red rot resistance in the variety selection programme is now a routine operation.