Great Lakes, great pollution

The Great Lakes basin of North America has received much attention because of the threat of pollution to the aquatic environment posed by industrial pollution and pesticide use. World Wildlife Fund (WWF) in the US and Canada has launched a campaign to promote pest management systems which rely to the greatest possible extent on biological processes. In a recent briefing, WWF described how pesticides are affecting the Great Lakes environment and strategies to reduce their impact.

The impacts of pesticides
About 57 million pounds (26 million kg) of pesticides are used in agriculture annually in the Great Lakes basin (75% in the US, the remainder in Canada). According to WWF, over half the pesticides used are probable or possible human carcinogens and one third are potential reproductive or endocrine disruptors. For example, atrazine, one of the most widely used herbicides, has been placed in these categories.

Reducing pollution
A number of local pesticide-reducing initiatives are saving farmers money. The Campbell Soup Company recently launched an ambitious effort to reduce pesticide applications by 50%, and reported that, after four years, it had exceeded this goal for three crops without sacrificing yields or quality. In 1993, 15 participating farmers in the Northeast Wisconsin Sustainable Farmers Network project grew wheat without herbicides on 568 acres and improved their profit by US$53 per acre. New potato crop management computer software developed at the University of Wisconsin is reducing spraying on more than 70,000 acres of potato production. In 1994, the systems are estimated to have saved US$5.9 million that would otherwise have been spent on pesticides and irrigation.

Pollution prevention
Farmers operate at different points on what WWF calls the ‘pesticide reduction spectrum’, and they will progress along it at different rates, using the following tools:

Control: At a minimum, farmers should dispose of used containers in a manner that minimises environmental contamination. Where pesticides are applied, buffer zones can reduce the volume of pesticides reaching water.

Efficient chemical management: Farmers should adopt techniques and technologies to apply pesticides with greater precision.

Multi-tactic IPM: Crop rotations, cover crops and other cultural tactics should be adopted as integral parts of most pest management systems but are more critical the farther a farmer moves toward the bio-intensive end of the pesticide reduction spectrum.

Bio-intensive (biologically based) systems: When sprays must be used, natural biopesticides, such as pheromones and the bacteria-based Bt pesticides have preference.

Conclusion
WWF US has concluded that the initiative should incorporate the following three factors:

• the health and environmental risks from pesticides currently used in the basin, although not yet fully understood and measured, are possibly severe;
• alternative management practices are technically available and economically promising;
• institutions in the region have the potential to promote substantial reductions in chemical methods of pest management.

Reducing reliance on pesticides in Great Lake Basin agriculture, 1996, WWF 1250 24th Street, NW, Washington, DC 2003, US, 16pp.