Armillaria mellea, commonly known as honey fungus, is a fungal pathogen that causes root rot in a wide range of woody and perennial plants. It is a soil-borne fungus that infects the roots of plants, eventually causing them to decay and die. Armillaria mellea is found throughout the world and can cause significant damage to forests, orchards, and other woody plantations. The fungus produces characteristic honey-colored mushrooms in the late summer and autumn, which can help with identification. Armillaria mellea is a difficult disease to control once it becomes established, but preventive measures such as good sanitation practices and avoiding planting susceptible species in infected soil can help reduce the risk of infection.