Hyphal Fusion, Nuclear Condition, And Perfect Stages of Three Species of Rhizoctonia

Abstract

SUMMARYComplete fusion occurred between two hyphae of the same isolate or closely related isolates of Rhizoctonia spp. Hyphae of Rhizoctonia ramicola did not fuse with hyphae of either R. solani or R. zeae.Hyphal cells of R. zeae and R. ramicola were always binucleate, whereas those of R. solani were always multinucleate. A multinucleate isolate of R. solani produced the basidial stage on the surface of previously sterilized soil. The basidial stage of this fungus was identified as Thanatephorus cucumeris (Frank) Donk.R. ramicola formed white, web-like basidial fructifications on the lower sides of infected leaves of Pittosporum tobira. Hypobasidia were 8.0-(11.1)-16.5 × 5.2-(7.8)-14.4 μ, epibasidia were almost the same length as hypobasidia, and basidiospores measured 5.2-(8.5)-10.5 × 3.4-(5.2)- 6.9 μ. The perfect stage of R. ramicola is described herein as Ceratobasidium ramicola.