Livestock Deaths Associated with Clavibacter toxicus/Anguina sp. Infection in Seedheads of Agrostis avenacea and Polypogon monspeliensis. Alan C. McKay, Field Crops Pathology Unit, South Australian Research and Development Institute, Waite Agricultural Research Institute, Glen Osmond, South Australia 5064. Kathy M. Ophel, Terry B. Reardon, and Jan M. Gooden. Department of Crop Protection, Waite Agricultural Research Institute, Glen Osmond, South Australia 5064; Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide, South Australia 5000; and Field Crops Pathology Unit, South Australian Research and Development Institute, Waite Agricultural Research Institute, Glen Osmond, South Australia 5064. Plant Dis. 77:635-641. Accepted for publication 26 January 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0635.

Flood plain staggers, a recently discovered poisoning of livestock, has been linked to Clavibacter toxicus infection in the seedheads of blown grass, Agrostis avenacea, in northern New South Wales and annual beardgrass, Polypogon monspeliensis, in the southeast of South Australia. The same bacterium on annual ryegrass, Lolium rigidum, causes the poisoning of livestock known as annual ryegrass toxicity. Strains of C. toxicus from A. avenacea and P. monspeliensis were indistinguishable from strains from L. rigidum based on colony morphology, serological reactions, and bacteriophage specificity. Bacteriophages isolated from C. toxicus on the three hosts were indistinguishable from each other based on DNA restriction patterns. In allozyme studies, considerable variation was observed between the C. toxicus strains from the three hosts, but the variation was within the range exhibited by a single species. C. toxicus is carried into L. rigidum by a seed gall-forming nematode, Anguina funesta. Anguina nematodes are also associated with C. toxicus infection of A. avenacea and P. monspeliensis. Allozyme studies indicate that the same Anguina species probably infects both grasses, and that it is not Anguina funesta, Anguina agrostis, Anguina tritici, or the species found on velvetgrass (Holcus lanatus). This is the first recording of a nematode other than Anguina funesta as a vector for C. toxicus. The new vector broadens the range of grasses that the bacterium can infect.

Keyword(s): livestock poisoning.