Redheadia quercus gen. et sp. nov., the teleomorph of Mycopappus quercus, the frosty mildew fungus in Quercus acutissima

The teleomorph of Mycopappus quercus causing frosty mildew in Quercus acutissima is described as a new genus and species, Redheadia quercus, in the Sclerotiniaceae. Apothecia sprout from sclerotia on the fallen infected leaves kept for 10 months at 5°C and subsequent incubation at 15°C under diffused room light. Typical zonate lesions and multicellular propagules of M. quercus are produced on Q. acutissima, by mycelial inoculation using an isolate from a single ascospore, confirming the teleomorph–anamorphic connection. No significant differences are observed between cultured colonies of isolates from the ascospore and those from the propagule. Sclerotia and microconidia of the fungus are produced on culture media.