Characterisation of Rhizoctonia solani isolates causing root canker of lucerne in Australia

The fungus causing Rhizoctonia root canker of lucerne in western Queensland has been characterised as a new subgroup within anastomosis group (AG 6) of Rhizoctonia solani. Isolates from two sites showed identical rDNA ITS sequence homology but could be differentiated based on DNA fingerprints. The lucerne isolates did not cause disease on wheat, indicating they are genetically different from the AG 6 subgroup that causes crater disease on wheat in South Africa. Root canker symptoms were produced on all commercial Australian cultivars of lucerne tested.