Response of subterranean clover cultivars to root rot fungi

Twelve widely grown cultivars of subterranean clover (Trifolium subterraneum) were screened both under controlled environment conditions for their resistance to five fungi commonly associated with root rot and under field conditions for their resistance to natural root infections. All cultivars showed decreased seedling survival (particularly from Pythium irregulare and Rhizoctonia solani), tap and lateral root rot (particularly from Fusarium avenaceum, P. irregulare, and R. solani) and reduced plant size (particularly from R. solani and P. irregulare). Individual cultivars generally differed in their response to the five pathogens and for any one pathogen there was generally a range of cultivar susceptibilities. Cultivars with the best resistance to individual root pathogens were identified. The results for the five individual pathogens under controlled conditions only showed correlation with field data for some of the parameters compared.