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What research has been done on additional alternatives to herbicides?

Category: Vegetation Management

In the early- to mid-1990’s significant research was done across the country to explore and test a wide range of vegetation management alternatives. While this work has led to a better understanding of how to optimize tools such as manual cutting, alternatives such as grazing animals, fungi and mulches were found to be largely ineffective in forest management.

To date, several million dollars have been spent in Canada and elsewhere to investigate the role that tools such as grazing animals, fungi and mulches might play in Integrated Vegetation Management programs. The Vegetation Management Alternatives Program established by the Ontario Ministry of Natural Resources in the early 1990s is an excellent example of these efforts. Conclusions from this research indicate that the high cost, increased variability in success, and relatively low efficacy of these approaches make them impractical for all but very small-scale applications (Wagner et al. 2001). For example, a national effort was undertaken to develop and register the indigenous (native) fungus Chondrostereum purpureum as a microbial biocontrol agent for forest vegetation management (Thompson et al. 1992, Pitt et al. 1999, Harper et al. 1999). Results from these trials showed it to be effective in controlling re-sprouting of some woody competitive species. Two derivative commercial products were ultimately registered for use. However, use of these products has been minimal in operational forest practice for several reasons including: 1) a total lack of efficacy on herbaceous competitor species; 2) ineffectiveness on some particular woody species; and 3) the need for manual or mechanical cutting immediately prior to application of the fungus, which increases overall operational costs. Other alternative approaches, such as the use of mulch mats have also generally proven to be both ineffective and far too costly (Thomas et al. 2001, Harper et al. 2005) for widespread use in operational forestry.

Bell, F.W., Pitt, D.G., Morneault, A., Pickering, S. 1999. Response of immature trembling aspen to season and height of cut. Northern Journal of Applied Forestry 16(2): 108-114.

Harper, G.J., Comeau, P.G., Hintz, W., Wall, R.E., Prasad, R., Becker, E.M. 1999. Chondrostereum purpureum as a biological control agent in forest vegetation management. II. Efficacy on Sitka alder and aspen in western Canada. Canadian Journal of Forest Research 29(7): 852-858.

Harper, G.J., Comeau, P.G., Biring, B.S. 2005. A comparison of herbicide and mulch mat treatments for reducing grass, herb, and shrub competition in the BC interior Douglas-fir zone - Ten-year results. Western Journal of Applied Forestry 20(3):167-176.

Pitt, D.G., Dumas, M.T., Wall, R.E., Thompson, D.G., Lanteigne, L., Hintz, W., Sampson, G., Wagner, R.G. 1999. Chondrostereum purpureum as a biological control agent in forest vegetation management. I. Efficacy on speckled alder, red maple, and aspen in eastern Canada. Canadian Journal of Forest Research 29(7):841-51.

Thomas, K.D., Reid, W.J., Comeau, P.G. 2001. Vegetation management using polyethylene mulch mats and glyphosate herbicide in a coastal British Columbia hybrid poplar plantation: four-year growth response. Western Journal of Applied Forestry 16(1):26-30.

Thompson, D.G., Watson, A.K., Dorworth, C., Dumas, M., Strunz, G., Jobidon, R., Haris, P., Castellok, J., Wagner, R. 1992. BICOVER: A national research network on biological control of competing vegetation. In: R. G. Richardson, compiler, Proceedings of the First International Weed Control Congress. Melbourne, Australia.

Wagner, R.G., Bell, F.W., Campbel, R.A. 2001. Vegetation management. Pages 431-457 In: R.G. Wagner, and S.J. Colombo, eds. Regenerating the Canadian Forest: Principles and practice for Ontario. Fitzhenry & Whitside, Markham, ON.