Inonotus tomentosus is a fungal pathogen of commercially valuable tree species, and one of the most important biotic disturbance agents in sub-boreal and boreal forests in Canada. Little is known about the relative roles of basidiospores and root contact in disease spread. To investigate the genetic diversity of I. tomentosus, and whether or not forest management affects the mode of disease spread, three natural stands and three 30-year-old plantations in the sub-boreal spruce forests of central British Columbia were intensively sampled. I. tomentosus was isolated from infected trees, and vegetative compatibility groups were determined by dual cultures. DNA was extracted from each isolate and amplified with random primers for RAPD analysis, and specific primers for SSCP (two mitochondrial, one nuclear). A high level of genetic diversity in I. tomentosus was observed in both stand types with few isolates in each clone. The number of unique genotypes was higher in plantations than in natural forests. This suggests that there is a greater incidence of infection by basidiospores in managed stands than natural forests, and that strategies to limit spread of root disease in plantations, such as minimum planting distances around colonized stumps, may not be as effective as once thought.
Kathy J. Lewis.
Gibson, Susan, Lewis, Kathy J.. 2004. Comparison of the genetic diversity and mode of spread of the spruce pathogen Inonotus tomentosus in old-growth forests and plantations. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report