Interactions between Avena and Puccinia species I. The wild hosts: Avena barbata Pott ex Link, A. fatua L. A. ludoviciana Durieu.
When 21 populations of wild oats collected throughout NSW were assessed at the seedling stage against 4 races of P. coronata, those from northern NSW were significantly more resistant and diverse in their infection response than southern ones. Differences in the distribution of resistance to 4 races of P. graminis [f.sp.] avenae were considerably less marked; for populations of Avena fatua there was a non-significant increase in resistance in the N. while A. barbata showed no such difference between northern and southern populations. No differences were detected in the av. response of populations of any of the 3 A. spp. to infection by P. coronata, and for P. graminis f.sp. avenae in northern populations. The importance of intra-population diversity in infection response as a means of reducing disease is discussed.<new para>ADDITIONAL ABSTRACT:<new para>In a seedling inoculation study of 21 New South Wales populations of the above Avena species, considerable variation was found between and within populations in response to infection by four cultures of P. coronata and four of P. graminis. In general, northern populations were more resistant and more diverse in response to P. coronata than southern populations. The three species did not differ in average population response to P. coronata. Population responses to P. graminis were more variable than to P. coronata.