How Rhizoctonia stem rot disease causes damage in carnation?

Rhizoctonia stem rot is caused by the soilborne fungus and the symptoms on rooted cuttings is a moist greyish-black rot at the soil line, which causes the top of the plant to wilt and die. On older plants the rot may extend a couple of inches above the soil line, inducing bark decay, which is easily rubbed off. Occasionally brown mycelial strands may be seen on the surface of diseased tissue. The fungus causing this disease in Kula, Maui, has been found to belong to a genetically distinct stock, known as anastomosis grouping AG2-2 (15).