Rhizoctonia

Rhizoctonia is a genus of fungi in the family Ceratobasidiaceae. Species form thin, effused, corticioid basidiocarps (fruit bodies), but are most frequently found in their sterile, anamorph state. Rhizoctonia species are saprotrophic, but some are also facultative plant pathogens, causing commercially important crop diseases. Some are also endomycorrhizal associates of orchids. The genus name was formerly used to accommodate many superficially similar, but unrelated fungi. As of 2025, the synonymisation of several genera under a unified Rhizoctonia was formalised, and the genus now includes names formerly circumscribed under Moniliopsis, Ceratobasidium, Thanatephorus, Uthatobasidium, Koleroga, Cejpomyces, Oncobasidium, Ypsilonidium, Ceratorhiza, and Tofispora. As currently circumscribed, the genus contains 52 accepted species.

==Taxonomy== ===History=== ====Anamorphs==== Rhizoctonia was introduced in 1815 by French mycologist Augustin Pyramus de Candolle for anamorphic plant pathogenic fungi that produce both hyphae and sclerotia. The name is derived from Ancient Greek, ῥίζα (rhiza, "root") + κτόνος (ktonos, "murder"), and de Candolle's original species, Rhizoctonia crocorum (teleomorph Helicobasidium purpureum), is the causal agent of violet root rot of carrots and other root vegetables. Subsequent authors added over 100 additional names to the genus, most of them plant pathogens bearing only a superficial resemblance to the type species. Rhizoctonia thus became an artificial form genus of anamorphic fungi comprising a diverse range of unrelated species.