COMPARATIVE EFFICACY OF BIOLOGICAL AND CHEMICAL CONTROL OF THE VEGETATIVE REPRODUCTION IN BETULA-PAPYRIFERA AND PRUNUS-PENSYLVANICA

The effectiveness of various treatments to control stump sprouting of Betula papyrifera and Prunus pensylvanica was examined under field con ditions in Quebec. The experiment involved six stump sprouting-control treatments organized in a randomized complete block design with 15 re petitions: two isolates of the indigenous fungus Chondrostereum purpur eum (biological control), a heat-killed blank of the inoculum of C. pu rpureum, bialaphos (biorational control), glyphosate (chemical control ), and the untreated control. Control of stump sprouting was evaluated 1 and 2 years after treatment by the proportion of stumps with living sprouts and by the mean number of Living and dead sprouts per stump. One and 2 years after treatment, biological control was comparable to chemical control in terms of frequency of sprouting and mean number of sprouts per stump, for B. papyrifera. While the two fungal isolates a ffected stump sprouting in B. papyrifera similarly, P. pensylvanica sh owed two significantly different responses, suggesting that virulence could vary among isolates of C. purpureum, particularly for less susce ptible species. One year after treatment with C. purpureum, an infecti on analysis was performed to assess the extent of colonization within the stumps of both species. Results suggest that the extent of coloniz ation was not related to the level of control of stump sprouting. (C) 1998 Academic Press.