Canadian Forest Service Publications
Predisposing of forest weeds by chemical and manual cutting treatments to enhance the efficacy of selected biocontrol agents. 2001. Shamoun, S.F. Page 283 in M. Vurro, J. Gressel, T. Butt, G.E. Harman, A. Pilgeram, R.J. St. Leger, and D.L. Nuss, editors. Enhancing Biocontrol Agents and Handling Risks. IOS Press and Kluwer Academic Publishers, Amsterdam, The Netherlands.
Issued by: Pacific Forestry Centre
Catalog ID: 19126
Management of the competing forest vegetation “forest weeds” in conifer regeneration sites has been achieved primarily by using manual, mechanical and chemical strategies. Continued over-reliance on these methods conflicts with the philosophy of integrated forest vegetation management and with public concern for the environment, particularly as it relates to the use of synthetic herbicides in forestry. This has necessitated a more intensive search for alternative control measures that are cost effective, efficacious and environmentally safe. Inundative biocontrol strategy is a viable alternative and particularly valuable approach in ecologically sensitive sites. Invasive weedy Rubus spp. are targeted due to their capacity to rapidly invade conifer regeneration sites. A potential candidate, Fusarium avenaceum was selected, formulated and applied inundatively on target weed under greenhouse conditions. Test plants receiving formulated F. avenaceum combined with a chemical adjuvant 0.04% Silwet L-77® enhanced significantly the efficacy of the fungus by causing extensive foliar necrosis. To manage weedy hardwood species, an experiment was conducted to test the efficacy of Chondrostereum purpureum with manual cutting as compared to chemical herbicide for control of red alder (Alnus rubra). Results indicate that the efficacy of C. purpureum was enhanced by manually cutting the target weed prior to application of the formulated product of C. purpureum. Overall, C. purpureum plus manual cutting treatment was not significantly different from chemical herbicide, but was different from the formulation control and manual cutting treatment. Field testing, together with series of molecular markers developed to assess the impact of releasing selected isolates and environmental fate of C. purpureum should facilitate the registration process of the fungus. These two pathosystems are presented as examples for enhancement of biocontrol agents through predisposing the target weeds by chemical and manual cutting means, and will be discussed in detail.