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22. Leafy Spurge in Manitoba - The Fight to Keep Ahead.  Carla Pouteau, Weed Specialist, Manitoba Agriculture

Approximately 52,000 hectares (130,000 acres) are infested with leafy spurge in Manitoba. Most of the land infested is pasture and rangeland. Since the early 1980's, Manitoba Agriculture has been involved in the biological control of leafy spurge. Biocontrol was investigated after years of herbicide control failures. To date, nine different species of biocontrol agents have been investigated in Manitoba. Agriculture and Agri-Food Canada has been a major partner throughout the project. To date, Aphthona nigriscutis and A. cyparissiae have been the most successful insects managing spurge in Manitoba. However, these two insects appear quite particular in their habitat. In Manitoba, an insect is needed that will attack spurge in shaded areas (shrub and trees). Lobesia euphorbiana is showing some promise. However, this insect only prevents seed set. It does not affect the root system. Most recently (1990's), Aphthona lacertosa and A. czwalinae have established in Manitoba. Based on the success our neighbors to the south (North Dakota) have had with these two species, Manitoba Agriculture will concentrate on increasing the release sites of Aphthona lacertosa and A. czwalinae in future years. Aphthona czwalinae has proven very hardy in Manitoba as it has survived three weeks of flooding at one location.

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