Distribution in Australia and host plant specificity of Phomopsis emicis, a stem blight pathogen of Emex australis

Abstract

The stem blight pathogen, Phomopsis emicis, is widespread on Emex australis throughout those regions of southern Australia with a Mediterranean 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, are 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 ability. There was evidence that P. emicis was able to survive as an endophyte in Muehlenbeckia adpressa and Polygonum aviculare.