How to Manage Pests

Seasonal development and life cycle—Annosus root

Annosus root disease infects through roots and primarily affects conifers in areas where they grow naturally. Susceptible hosts, primarily pines, are often killed within several years. Other common hosts—true firs, Douglas fir, incense cedar, and hemlock—are usually not killed outright, but develop decay in heartwood that increases susceptibility to insect attack and wind damage.

The fungus can survive for several decades in the roots of dead hosts, so trees are often killed in a gradually expanding clump as nearby plants are infected through root contact. The fungus spreads long distances by airborne spores. Spores can germinate when they contact a freshly cut stump, creating a new infection center as the fungus spreads down through the stump into roots that contact nearby living trees.