First report of Mycopappus alni in Japan: species identification of the pathogenic fungus of a frosty mildew disease in Crataegus chlorosarca

Abstract

A leaf disease similar to frosty mildew disease caused by Mycopappus species was detected on the leaves of Crataegus chlorosarca in Tomakomai, Hokkaido Prefecture. From morphological observations and gene analyses of rDNA-ITS, the fungus was identified as M. alni, which causes leaf blight disease on Alnus spp., Betula spp., and a Pyrus sp. in North America and Turkey. This is the first report of M. alni in Japan and Crataegus as its new host genus.