Phytophthora spp. Associated with Container-Grown Plants in Nurseries in Western Australia. G. E. Hardy, Graduate Student, Soil Science and Plant Nutrition, School of Agriculture, University of Western Australia, Nedlands, Western Australia 6009. K. Sivasithamparam, Senior Lecturer, Soil Science and Plant Nutrition, School of Agriculture, University of Western Australia, Nedlands, Western Australia 6009. Plant Dis. 72:435-437. Accepted for publication 5 November 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0435.

Investigations on root rots of container-grown plants in 14 nurseries in Western Australia showed that one or more Phytophthora spp. were associated with rotted roots of 65 plant taxa. P. drechsleri, the most common species isolated, was associated with 73% of all plant taxa yielding Phytophthora spp., followed by P. nicotianae var. nicotianae (46%), and P. cactorum (23%). The number of Phytophthora spp. associated with any one host ranged from one to six, with individual plant specimens occasionally yielding up to four species of Phytophthora. The presence of various species of Phytophthora varied with nurseries, with one nursery harboring all eight species of Phytophthora encountered in this study. Nurseries appear to be a source of some of the outbreaks of root rot in home gardens and wild flower farms, with potential for wider spread of the fungi into natural forests.