Genus Armillariella is a type of fungus which can have various synonyms such as Armillariella mellea, honey fungus, shoestring root rot, bootlace fungus, and rhizomorph decay. These synonyms are often used to describe the same disease causing fungus, which can attack a wide range of trees and shrubs. Its aggressive nature makes it a serious concern for gardeners and arborists. The fungus spreads through underground rhizomorphs, which allow it to infect trees over large areas. Honey fungus produces mushrooms in the fall and winter, making it one of the most easily recognizable fungi. Armillariella is a tough and persistent invader that can survive for many years in soil and wood debris, making it difficult to eradicate completely.