Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) is a plant pathogenic fungus with a wide host range and worldwide distribution. It was discovered more than 100 years ago. R. solani frequently exists as thread-like growth on plants or in culture, and is considered a soil-borne pathogen. R. solani is best known to cause various plant diseases such as collar rot, root rot, damping off, and wire stem. R. solani attacks its hosts when they are in their early stages of development, such as seeds and seedlings, which are typically found in the soil. The pathogen is known to cause serious plant losses by attacking primarily the roots and lower stems of plants. Although it has a wide range of hosts, its main targets are herbaceous plants. R. solani is a basidiomycete fungus but the teleomo