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9.  LEAFY SPURGE BIOCONTROL IN THE LITTLE MISSOURI RIVER DRAINAGE

Don Kirby1

Abstract: The study began in 1997 to assess the impacts of biological control agents (Aphthona spp.) on leafy spurge and the ecological effects of leafy spurge on mixed grass prairie. Biocontrol agents, flea beetles, were released into leafy spurge infested rangeland in 1998. In only two growing seasons, leafy spurge control has been phenomenal. Of 98 release sites, 85% have had good leafy spurge control (>400m2), while only 5% have shown poor control (<200 m2). Leafy spurge canopy cover at release sites was reduced from 40% to less than 5%. Leafy spurge control has been similar across aspects, topographic positions, soil types and range sites. Results from a soil seedbank study indicated that over 70% of seedlings germinated from soils taken across light-to-heavy leafy spurge-infested rangeland were leafy spurge. Desirable cool- and warm-season grasses only comprised 5% of the seedlings germinated from soil cores. The dominance of leafy spurge and other "weedy" plant species in the soil seedbank of leafy spurge-infested rangeland will necessitate a long-term leafy spurge control program for these affected sites.
 


1Don Kirby, Professor, Department of Animal and Range Sciences, North Dakota State University, Fargo, ND 58105.

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