Canadian Forest Service Publications

Spread of Heterobasidion irregulare in eastern Canada towards northern natural forests of Pinus banksiana. 2013. Laflamme, G. Pages 162-163 in Conference proceedings, IUFRO Working Party 7.02.01 XIII Conference (Root and Butt Rot of Forest Trees), Firenze, Italy, September 4-10, 2011. Firenze University Press, Firenze, Italy.

Year: 2013

Available from: Laurentian Forestry Centre

Catalog ID: 35067

Language: English

CFS Availability: PDF (request by e-mail)


In eastern Canada, the forest pathogen Heterobasidion irregulare was first detected in southern Ontario in 1955. It was then reported under the name H. annosum. In 1989, we have found H. irregulare in the province of Quebec, near the Ontario border. The disease was there since 1981. During the following years, the disease has been found in few plantations in the same area. It has recently progress to Drummondville, Qc, North-East of the previous infection centres, as well as in eastern township. It is also progressing towards north with two infection centres at Saint-Jean-de-Matha, Qc. This last locality is not far from the natural stands of Pinus banksiana which extend from eastern Canada up to Yukon. Trials are being conducted to find out if fresh P. Banksiana’s stumps can be affected by the disease.

Plain Language Summary

Annosus root and butt rot was reported for the first time in Quebec in 1989. It is caused by the fungus Heterobasidion irregulare, which establishes itself in stands by colonizing freshly cut stumps. It then spreads through contact between healthy roots of other trees and those of an infected stump. Over the years, the fungus creates tree circles with high mortality rates, hence the French name of the disease, "maladie du rond".

Researchers estimate that Annosus root and butt rot is spreading northward a rate of 10 km/year, and will therefore reach jack pine stands in the boreal forest in just a few years. The researchers have shown that although this disease is mainly found in red pine stands, it can also attack jack pine and white pine. Its presence in red pine plantations stems from high volumes of commercial thinning in these stands, which is not the case for jack pine or white pine.

The risk of this disease spreading toward the boreal forest is therefore high. It could spread from eastern Canada to the Yukon – the distribution range of the jack pine – and could cause severe tree mortality across Canada.



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