A simple method for production of uniform inoculum of Rhizoctonia solani with strong pathogenicity

A simple method for production of uniform inoculum of Rhizoctonia solani AG 1-IC was developed by colonization of autoclaved rape seeds with the fungus. When five radish seedlings in a pot were inoculated with two colonized seeds, R. solani was able to kill essentially all the seedlings. The pathogen in one seed was able to cause death of more than two seedlings. Such colonized seeds have greater infection potential than sclerotia on the basis of number and weight. Rape seeds colonized with AG 2-1, AG 4 or AG 4 HG-1 were also effective in causing damping-off of radish seedlings. When colonized with R. solani AG 1-IC, other seeds of brassica including mustard cabbage, cauliflower, broccoli, spoon cabbage, head cabbage and Chinese cabbage were as pathogenic as colonized rape seeds. The technique is inexpensive and simple, and the material is readily available. Inoculum produced by this method is uniform in shape and size, and is strong in pathogenicity. The result also shows that the method is suitable for use in the detection of soils suppressive to the disease caused by R. solani.