Thanatephorus cucumeris

"R. solani" causes a wide range of commercially significant plant diseases. It is one of the fungi responsible for brown patch (a turfgrass disease), damping off (e.g. in soybean seedlings), black scurf of potatoes, bare patch of cereals, root rot of sugar beet, belly rot of cucumber, sheath blight of rice, and many other pathogenic conditions. The fungus, therefore, has a wide host range and strains of "R. solani" may differ in the hosts they are able to infect, the virulence of infection, selectivity for a given host ranges from nonpathogenic to highly virulent, the temperature at which infection occurs, the ability to develop in lower soil levels, the ability to form sclerotia, the growth rate, and survival in a certain area. These factors may not always show up given the environment and host that "Rhizoctonia" attacks.
"R. solani" primarily attacks seeds of plants below the soil surface, but can also infect pods, roots, leaves, and stems. The most common symptom of "Rhizoctonia" is "damping off", or the failure of infected seeds to germinate. "R. solani" may invade the seed before it has germinated to cause this pre-emergent damping off, or it can kill very young seedlings soon after they emerge from the soil. Seeds that do germinate before being killed by the fungus have reddish-brown lesions and cankers on stems and roots.