Identification of Fusarium solani f.sp. phalaenopsis in Australia

Fusarium solani is responsible for leaf yellowing and root and collar rot across a broad range of orchid species. The forma specialis, ‘phalaenopsis’, of Fusarium solani has recently been described using molecular methods as being the causal organism of disease in Phalaenopsis and Cymbidium orchids, and is the predominant pathogen of Taiwanese glasshouse-grown Phalaenopsis orchids. A study in 1996 reported F. solani as the causal agent of root necrosis of Cymbidium in NSW, Australia, but the study did not use molecular methods and predated the forma specialis ‘phalaenopsis’ designation. By comparing the phylogeny of the Australian isolates of F. solani from glasshouse-grown orchids with isolates of F. solani f.sp. phalaenopsis from Taiwan, the current study showed that the Australian and Taiwanese isolates were identical on the basis of the internal transcribed spacer (ITS) and β-tubulin (benA) regions and resulted in the first identification of F. solani f.sp. phalaenopsis in Australia.