Rhizoctonia leguminicola is a fungus that is a plant pathogen that most often attaches itself to the Trifolium pratense or red clover. It is also called Black Patch Disease. The infection is first seen as small black patches on the leaves of red clover (often on the bottom of the leaves first) and spreads to cover the entire plant, killing it. The hyphae of this fungus are white and web-like in appearance, just like those of other fungi. The consumption of the fungus can be harmful to any grazing animals, especially to horses and cows.