Abstract
Cutleaf teasel is a biennial, invasive weed found along roadsides throughout much of the central USA. Long-term management should, ideally, integrate chemical and cultural practices. Research in Missouri along Interstate Highway 70 was initiated to combine chemical applications with overseeding perennial grasses. A field experiment was carried out with a split-plot design (four replications), where the main plot factor was herbicide applied, and the sub-plot factor was grass species overseeded. Herbicide treatments comprised dicamba + diflufenzopyr, aminopyralid, triclopyr, and metsulfuron. Grass species included tall fescue + buffalograss or Canada wildrye + buffalograss. Cutleaf teasel coverage was reduced from 79% to 93% for all herbicide treatments except triclopyr, 5 months after the last herbicide application. Seedling counts of cutleaf teasel were lowest for aminopyralid by 6 months after the last herbicide application. The herbicide programme that provided >90% cutleaf teasel control and resulted in at least 65% grass establishment resulted in up to a 93% reduction in cutleaf teasel emergence by 363 days after initial herbicide application. Integration of applications of herbicides and desirable seeding grasses are needed over a long period to exclude cutleaf teasel in roadside areas.
Acknowledgements
We would like to thank Dr Harlan Palm and Mr David Kleinsorge for assistance with data collection. Appreciation is also extended to Mr Rand Swanigan, Head of Roadside Management and Maintenance with the Missouri Department of Transportation, for providing use of the research sites along Interstate 70.