Detection of an Invisible Foe: Annosus Root and Butt Rot

Annosus root and butt rot was first reported in Quebec in 1989. The causal fungus enters a pine stand by colonizing the surface of freshly cut stumps. The disease spreads through contact between the roots of infected stumps and the roots of healthy trees. After a few years, this radial spread, which occurs at a rate of about 1 m per year, results in a roughly circular patch of dead trees. The French common name of the disease, “maladie du rond,” comes from the circular areas of mortality. Annosus root and butt rot is spreading northward in Quebec at a rate of 10 km/year. Canadian Forest Service (CFS) researchers are working on methods to protect pines, the pathogen’s preferred host species, against this threat.