Mushrooms Honey Agarics Autumn, True. - Armillaria Mellea Is A Plant Pathogen And A Kind Of Honey Fungus. It Causes Armillaria Root Rot Many Plant Species. The Mushrooms Are Edible But Some People May Be Intolerant To Them. The Fungus Produces Mushrooms Around The Base Of Trees It Has Infected. As The Fungus Causes Root Rot, Symptoms Also Appear In The Crowns Of Infected Trees As Death And Dieback Of The Branches. Photo