Variation in colonisation of Lolium rigidum by isolates of Dilophospora alopecuri, an antagonist of the causal organisms of annual ryegrass toxicity

Abstract

The ability of 31 isolates of Dilophospora alopecuri to colonise Lolium rigidum co-inoculated with Anguina funesta and grown in pots outdoors was tested over 2 years. The isolates were collected from 3 grass hosts from sites across the southern mainland states of Australia. Marked variation among isolates of different host and regional origins was found. Isolates from L. rigidum showed the greatest colonisation with a mean of 16 infected inflorescences per 240 mm pot containing 32 plants. Isolates from the other hosts, Avena sativa, Holcus lanatus and Polypogon monspeliensis, only resulted in means of 1.9, 7.7 and 1.3 infected inflorescences per pot, respectively. The data allow selection of an aggressive isolate for dissemination for antagonism of A. funesta, one of the causal agents for annual ryegrass toxicity.