Interactions between Avena and Puccinia species II. The pathogens: Puccinia coronata Cda and P. graminis Pers. f.sp. avenae Eriks. & Henn.
A 5-yr survey in NSW revealed considerable annual variation in the abundance, racial diversity and virulence of both pathogen populations. Racial diversity was greater in the northern than in the southern half of the State. On av., isolates of P. coronata and P. graminis [f.sp.] avenae from the N. were respectively 22.4 and 17.5% more virulent than those from the S., although the differences were not statistically significant. The relative importance of cultivated and wild oats as hosts was assessed. The implications of the results for an understanding of host-pathogen co-evolutionary interactions is discussed.<new para>ADDITIONAL ABSTRACT:<new para>Differences in the virulence and racial diversity of P. coronata and P. graminis f. sp. avenae are reported from a five-year survey of the pathogens on cultivated oats and the wild species A. barbata, A. fatua and A. ludoviciana in New South Wales, Australia. The implications of the findings for an understanding of host-pathogen coevolutionary interactions are considered.