Description
Heterobasidion irregulare is a tree root rotting pathogenic fungus that belongs to the genus Heterobasidion, which includes important pathogens of conifers and other woody plants. It has a wide host and geographic range throughout North America and causes considerable economic damage in pine plantations in the United States. This fungus is also a serious worry in eastern Canada. Due to the ecology, disease type, host range/preference, interfertility group, and genetic information, H. irregulare (formerly known as Heterobasidion annosum P ISG) was designated a new species and distinguished from Heterobasidion occidentale (formerly known as Heterobasidion annosum S ISG).