Early Detection Best Defence against Invading Plants

Purple loosestrife prepares to bloom; other invasive species could be on the way

Oak Hammock Marsh, Man., July 18, 2005 — Purple loosestrife is poised to bloom in areas across Manitoba and a local agency is asking Manitobans to help them to combat this and other invading plants that threaten wetlands and other natural habitats.

Since 1992, the Manitoba Purple Loosestrife Project (MPLP), a partnership of organizations including Ducks Unlimited Canada, Manitoba Conservation, the City of Winnipeg, Manitoba Weed Supervisors Association, Manitoba Naturalists Society, Delta Waterfowl and Environment Canada, has been actively working in the province to identify and control purple loosestrife infestations. This year, the MPLP is warning Manitobans about other plants that pose similar threats to the province’s natural ecosystems.

“Purple loosestrife and other non-native species can quickly become the most dominant plant in a wetland, lake, creek or retention pond. Unfortunately, they out-compete native vegetation and reduce the biodiversity of plants and animals these areas can support,” says Cory Lindgren, biologist and manager, MPLP.

Purple loosestrife and other invasive plants are introduced species. Purple loosestrife, for example, is believed to have made its way to North America from Europe in the 1800s. Since then, the plant has crept its way across Canada, invading wetlands and waterways. Most native plants, on the other hand, are beneficial species with sufficient natural controls to limit their growth.

Biological control in the form of loosestrife-eating beetles is being used to manage some purple loosestrife infestations. According to Lindgren, between 30,000 and 40,000 beetles will be released in the province this year at sites around Lake Winnipeg and southern Manitoba.

Other invasive aquatic and wetland plants have been imported into Manitoba and planted as ornamentals in water gardens. One such species is the flowering rush, which is an aquatic plant that has been introduced into several Manitoba water bodies including the Winnipeg River, Red River and Netley-Libau Marsh. This exotic species can form dense stands that may interfere with recreational lake use, crowd out native plants and in turn harm fish and wildlife species.

Salt cedar is one of a number of invasive aquatic plants on the verge of introduction into Manitoba. A single salt cedar plant can “drink” over 200 gallons of water per day, drying up entire lakes. This species has invaded parts of the U.S. including North Dakota, and is expanding its range towards southwestern Manitoba.

Millions of dollars are spent annually in parts of Canada to control invasive species. That’s why early detection and control of invasive species is key, Lindgren says. “Resource managers and the general public can reduce both ecological and economic impacts of these species just by reporting their location. It makes it easier for us to manage a few infestations rather than thousands of hectares.”

Lindgren has these suggestions for Manitobans interested in helping MPLP control purple loosestrife and other invasive plants:

Report it

To report purple loosestrife and other non-native aquatic plant sightings, please contact Cory Lindgren MPLP at (204) 467-3269.

Remove it

Purple loosestrife is a noxious weed in Manitoba and therefore illegal to plant or sell; people are required to remove it from their property. According to Lindgren, many people have this pretty flowering perennial in their gardens and are unaware that it is choking life out of wetlands across Canada.

He urges people not to plant any variety of purple loosestrife, including Morden Pink, Mordon Gleam and Dropmore Purple, and to uproot and destroy any existing plants as soon as possible to prevent the spread of seeds. Dig out the plant and root system and let it dry for 10 days. When dead, place the plant materials into two dark garbage bags, knot the bag tightly and dispose in a landfill.

Replace it

Environmentally safe alternatives to purple loosestrife and other invasive plants are available. Contact your local plant supplier for examples of other environmentally acceptable options

For more information, visit the Manitoba Purple Loosestrife Project website at www.purpleloosestrife.org.

For more information:

Cory Lindgren
Manager, Manitoba Purple Loosestrife Project
Ph: (204) 467-3269

E-mail: c_lindgren@ducks.ca

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