Annosum Root Rot - Biology

Infection most often occurs when basidiospores, produced by the fruit body, land and germinate on the surface of a freshly cut stump. This infection process creates a strong relationship between Annosum root disease and thinned stands.

Basidiospores are most often produced when the temperature is between 41º - 90º F (5º - 32º C) and can be carried in the wind over hundreds of miles; most spores are deposited within 300 feet (90 meters).

The fungus colonizes the stump tissue, moves into the root tissue and progresses from tree to tree via root contact at the rate of approximately 3.2- 6.5 feet per year (1-2m/yr). Infection through root and lower stem wounds can also occur. This has been observed in Wisconsin on white pine regeneration in a red pine plantation.

Heterobasidion annosum degrades both the lignin and the cellulose and causes a stringy yellow decay in the roots and lower stem.

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Stringy yellow decay caused by Heterobasidion. WDNR Photo