- Additional Plants: native plants
- Animal Production: range improvement
- Education and Training: demonstration, extension, farmer to farmer, focus group, on-farm/ranch research, participatory research
- Pest Management: weed ecology
Spotted knapweed (Centaurea stoebe), an aggressive competitor and ecologic threat, produces 25-35 flowers/head, 60 heads/plant and 5,000-40,000 seeds/meter squared annually. Prescribed sheep grazing, a tool used to control spotted knapweed, can offsets high costs of control and environmental concerns surrounding herbicides. However, spotted knapweed forms new flowers after prescribed sheep grazing is applied during the bolting or flowering stage. It is unknown if these new flowers produce viable seeds by the end of the growing season. The purpose of this two-year study was to determine the appropriate timing(s) or combination(s) of timings of defoliation on spotted knapweed to reduce viable seed production.
Objective 1: Evaluate the effects of timing of spotted knapweed defoliation on: a) the number of buds/flowers present, b) the percent viability of filled seeds and c) the total number of viable seeds produced to determine the best timing of spotted knapweed defoliation to minimize viable seed incorporation into the seedbank annually.
Objective 2: Combine results of this study with past research and existing grazing prescription protocols to refine the technique of using sheep grazing to control spotted knapweed.
Objective 3: Educate ranchers, other landowners, livestock operators, county extension personnel, county weed district personnel, state and federal agency personnel, Montana State University researchers and concerned citizens about how properly timed sheep grazing to control spotted knapweed can reduce the amount of viable seed applied to the seedbank in a single growing season and can enhance the ecological integrity of the land.