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Dilophospora alopecuri
a fungus antagonistic to nematodes
Seed gall nematodes, Anguina spp., are vectors for bacteria Clavibacter (Rathayibacter) spp. and the fungus Dilophospora alopecuri. These microbes colonise nematode galls and host grass inflorescences. Both organisms are antagonistic to the nematode, with the fungus having a greater impact on the nematode population than the bacterium. The bacterium and fungus compete with the nematode for nutrients, oxygen, and space. Clavibacter toxicus produces a toxin which cause livestock deaths.
 Cells of Clavibacter (Rathayibacter) toxicus adhering to the cuticle of Anguina funesta juveniles. Bacterial cells are the dark points on the outer surface of the nematodes. Photo by B. Stynes |
 Conidia of Dilophospora alopecuri, with characterisitic adhesive appendages, attached to the cuticle of Anguina funesta juvenile. Photo I. T. Riley |
 Ryegrass colonised by Anguina funesta and Clavibacter (Rathayibacter) toxicus. From left to right, ryegrass seed in chaff, seed without chaff, nematode gall, and nematode gall colonised by bacterium. Photo by I. T. Riley |
 Black stroma of Dilophospora alopecuri in ryegrass. The fungus is carried in by Anguina funesta but its growth inhibits nematode gall initiation and reproduction. Photo by I. T. Riley |
Examination of areas in Australia, where the incidence of livestock deaths from toxic ryegrass have declined, indicated that the fungus had become abundant and was the most likely contributor. This was confirmed in pot and field experiments.
* The above information and photographs were supplied by Ian T. Riley at The University of Adelaide.