What is “<em>Sclerotium nivale</em>”? Old and new snow mold in Russia

Abstract

It has been reported that Sclerotium nivale Elenev causes winter damage (Sclerotium disease) to winter rye and turfgrass in the European part of Russia, Ukraine, and Estonia. This fungal name is invalid, and their biological characteristics are limited. Since all reports on this fungus and their disease are written in Russian and Estonian without our recent review (Tkachenko 2013), few phytopathologists outside the former Union of Soviet Socialist Republics know about this fungus. We found symptoms of Sclerotium disease in Moscow, Russia, and we obtained asexual spore-forming ascomycetous (absent clamp connections) and basidiomycetous (had clamp connections) isolates from their white sclerotia. &amp;ldquo;S. nivale&amp;rdquo; was composed of several fungal species of ascomycetes and basidiomycetes. The ascomycetous isolate had the ability to grow under the snow cover, and phylogenic analysis suggested that the ascomycetous isolate had high homology (98&amp;ndash;99%) with genera of Karstenula and Paraphaeosphaeria. We previously reported sclerotia of Typhula sp. were formed ca. 2 weeks to 1 month after the snow melt, remained immature as mycelial aggregations after snow melt, and matured without snow. In addition, Paraphaeosphaeria included sclerotium parasites such as P. minitans. Several cold-adapted fungi infected basidiomycetous sclerotia of Typhula spp. and others. These findings suggested that ascomycetous S. nivale was the possibility of the mycoparasite under the snow.