DISTRIBUTION IN AUSTRALIA AND HOST-PLANT SPECIFICITY OF PHOMOPSIS-EMICIS, A STEM BLIGHT PATHOGEN OF EMEX-AUSTRALIS

The stem blight pathogen, Phomopsis emicis, is widespread on Emex aust ralis throughout those regions of southern Australia with a Mediterran ean climate. Host specificity tests showed that P. emicis was able to cause leaf lesions or stem collapse on five closely related species, E . australis, E. spinosa, Rumex alcockii, R. dumosus and R. pulcher, in the Polygonaceae. Two of these species, R. alcockii and R. dumosus, a re native to Australia and the others are introduced weeds. P. emicis was able to colonize the wounded or senescent tissue of several other plant species, thereby demonstrating its facultative saprophytic abili ty. There was evidence that P. emicis was able to survive as an endoph yte in Muehlenbeckia adpressa and Polygonum aviculare.