Evaluation of resistance to five isolates of Puccinia coronata f sp lolii in 19 perennial ryegrass cultivars

This paper seeks to provide information on the differences in resistance to Puccinia coronata f. sp. lolii of the many perennial ryegrass (Lolium perenne) cultivars available in Australia, and on the variation in resistance to this pathogen within these cultivars. This information will help farmers to select crown rust resistant cultivars suited to their area, and indicate to perennial ryegrass breeders the diversity of crown rust resistance within the cultivars and lines screened. Twenty genotypes of 14 cultivars and 5 advanced breeding lines of perennial ryegrass were screened for their reaction to 5 isolates of P. coronata f. sp. lolii. The isolates were collected from South Australia, southern Queensland, and 3 separate regions of Victoria. Tasdale, Victorian, Martlet, Tasmanian No. 1, and D1 were significantly (P < 0 . 05) more susceptible to crown rust than all other cultivars and lines. Embassy, D4, and D16 were the most resistant of the 19 cultivars and lines screened. Within all cultivars and lines there was significant (P < 0 . 05) difference between genotypes in their susceptibility to P. coronata f. sp. lolii. This type of screening for genotype reaction could enable differential test plants to be selected for determining the presence of P. coronata f. sp. lolii pathotypes, an area that requires further research.