The black stain fungus infects and kills several species of western conifers. The fungus colonizes water conducting tissues of the hosts roots, root collars, and lower stems, ultimately blocking the movement of water to foliage. Severely infected trees exhibit wilting symptoms.
Black stain kills young trees within a year or two of infection.
Tree mortality associated with the disease is often mistakenly attributed to other, more easily identified root disease or to bark beetles, which are commonly associated with the rapid decline and death of black stain-infected trees. Fungus Colorado host tree Leptographium. In early stages of decline, terminal growth is reduced and older needles become chlorotic. As the disease progresses, older needles are shed prematurely, new needles are somewhat stunted and yellow, and reduced growth is evident on lateral branches. In advanced stages, new growth is compact and chlorotic, with a tufted appearance, and tree crowns exhibit very sparse foliage.