Herbicides are the primary method used to control exotic, invasive plants. This study evaluated restoration efforts applied to grasslands dominated by an invasive plant, sulfur cinquefoil, 6 yr after treatments. Of the five herbicides we evaluated, picloram continued to provide the best control of sulfur cinquefoil over 6 yr. We found the timing of picloram applications to be important to the native forb community. Plots with picloram applied in the fall had greater native forb cover. However, without the addition of native perennial grass seeds, the sites became dominated by exotic grasses. Seeding resulted in a 20% decrease in exotic grass cover. Successful establishment of native perennial grasses was not apparent until 6 yr after seeding. Our study found integrating herbicide application and the addition of native grass seed to be an effective grassland restoration strategy, at least in the case where livestock are excluded.
Nomenclature: Picloram, sulfur cinquefoil, Potentilla recta L.
Management Implications:
If the objective is simply to reduce abundance of an invasive plant for temporary control, one application of the proper herbicide may suffice. This study found that a one-time application of picloram effectively reduced sulfur cinquefoil for 6 yr.
Although herbicide applications were successful at reducing sulfur cinquefoil abundance, they were was not successful at reducing overall exotic plant cover, as other exotics species, primarily annual grasses generally replaced sulfur cinquefoil.
Simply seeding native perennial grasses into plots was effective at reducing sulfur cinquefoil abundance, and herbicide application combined with native grasses seeding provided best control of sulfur cinquefoil while at the same time increasing native species abundance.
Seeding success appeared poor in the first 1 to 3 yr because of the slow growth and small size of native perennial grass species in the years immediately following seeding. Therefore, longer-term monitoring is needed to evaluate success of seeding efforts.
