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Abstract
The fungus Chondrostereum purpureum, applied on freshly cut surfaces of four broadleaf tree species (Betula papyrifera, Populus tremuloides, Prunus pensylvanica and Acer saccharum) provided control of stump sprouting varying from 76 to 100% with respect to either the test strain or the species treated. To assess if undesired infections had occurred following the treatment, samplings were conducted in the vicinity of the experimental sites. Random amplified polymorphic DNA (RAPD) markers were developed to discriminate between natural infections and those induced by spores emitted from test strains. The biological treatment did not lead to added risk to non-target trees. Since the proliferation of spores from a genotype used as a biophytocide might induce genetic changes in the local population, accurate information about the extent of genetic variation within C. purpureum was required. The RAPD fingerprints of 43 isolates obtained from 14 different host species in three forest zones of the province of Quebec, and pseudo-allelic frequencies estimated at each of 22 putative RAPD loci for 92 isolates, originating from four Canadian ecological regions, were analysed. The results suggested that any genotype selected for its efficacy to control stump sprouting should be considered indigenous in all Canadian regions of intended used and that genetic diversity would be great enough to negate the risk of introducing new genes into local populations.
