Submitted to: Pacific Northwest Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2005
Publication Date: 5/1/2006
Citation: Goetz, J., Dugan, F.M. 2006. Alternaria malorum: a mini-review with new records for hosts and pathogenicity. Pacific Northwest Fungi. 1(3):1-8. DOI: 10.2509/pnwf.2006.001.003. Interpretive Summary: The fungus Cladosporium malorum was first discovered in Washington State. Originally described from stored apple fruits in 1930, it was soon discovered to be widely prevalent and often dominant on market wheat from that state. In subsequent years, the fungus was documented on many different hosts, including seeds of various plants of agronomic importance. However, host-fungus indices from the 1970s to the present have few records for this fungus. This mini-review cites numerous records overlooked by the modern databases and indices. Most of these records are from the 1930s through the 1960s, but some are more recent. We also present new records for isolation of the fungus (from conifer roots) and new records of pathogenicity (on artificially inoculated tomato fruits). The modern name of the fungus is Alternaria malorum (because of molecular-genetic and metabolic affinities, and certain microscopic characters). Cladosporium malorum is neither as rare as previously thought, nor is it a true Cladosporium.
Technical Abstract: Modern host-fungus indices and databases contain deceptively few entries for Alternaria malorum or its synonym, Cladosporium malorum. Close inspection of literature from the 1930s through the1960s indicates more hosts and wider prevalence than more modern indices and databases indicate. Reports from 2002 to the present document diverse additional hosts in the Pacific Northwest, including roots of Pinus ponderosa and Pseudotsuga menziesii, the first reports from gymnosperms. Cherry tomato and grape tomato (Lycopersicon esculentum) were found to be hosts for A. malorum by artificial inoculation. Rarely documented in synoptic indices or databases in the last 20 years, the Cladosporium-like C. malorum is neither rare nor a true Cladosporium.