Canadian Forest Service Publications
Spread of Inonotus tomentosus from infection centres in spruce forests in British Columbia. 1992. Lewis, K.J.; Morrison, D.J.; Hansen, E.M. Canadian Journal of Forest Research 22: 68-72.
Issued by: Pacific Forestry Centre
Catalog ID: 3255
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The path of infection in spruce (Picea glauca x engelmannii Engelm.) by Inonotus tomentosus (Fr.:Fr.) S. Teng. and disease development, were studied by excavating roots of trees in five plots situated at the edge of disease centres in 60- to 140-year-old stands. Root contacts resulted in infection only when ectotrophic or intrabark mycelium was present. The fungus directly penetrated the bark of roots less than 4 cm in diameter; bark disruptions, such as branch points for secondary roots, facilitated penetration to the cambium, Infection of the wood in 1- to 10-cm roots was often (54%) through infection of a feeder root. In roots less than 5 cm in diameter, mycelium in the bark preceded stain and decay in the root xylem by approximately 20 cm. In living roots larger than 5 cm in diameter, decay and stain was limited to long columns in the heartwood. Once one of these larger roots died, the fungus colonized its sapwood and bark, but did not grow distally in the root. Expression of crown symptoms was more closely related to root mortality than to the percentage of roots colonized.