Interactions Between Avena and Puccinia Species. II. The Pathogens: Puccinia coronata CDA and P. graminis Pers. F. Sp. avenae Eriks. & Henn.

Abstract

A 5-yr survey of the oat crown rust and oat stem rust pathogens (P. coronata and P. graminis avenae) in New South Wales [Australia], found considerable annual variation in the abundance, racial diversity and virulence of both pathogen populations. The racial diversity of both pathogens was significantly greater in the northern than the southern half of the State. On average, isolates of P. coronata and P. graminis avenae from northern New South Wales were, respectively, 22.4 and 17.5% more virulent than those from the south. However, these differences were not statistically significant. The relative importance of cultivated and wild oats [A. barbata, A. fatua, A. ludoviciana] as hosts to the 2 pathogens is assessed. The implications of these results for an understanding of host-pathogen co-evolutionary interactions is discussed.