Chemical control. Presently only one herbicide available to homeowners, Tenacity (active ingredient mesotrione), provides selective control of nimblewill in cool-season lawns such as Kentucky bluegrass, tall fescue, fine fescues and perennial ryegrass. Application rates can vary so follow label directions. It is not approved for use on warm-season grasses such as zoysia grass. Several applications are needed for good control and a non-ionic surfactant should be added to the mix. Nimblewill will become bleached and white as it dies.
A cheaper control method is to apply a non-selective, post-emergent herbicide such as glyphosate (Roundup) to patches of nimblewill and then replant the areas. Apply the herbicide when the nimblewill is actively growing during the summer. Applying in late autumn to early spring when it is dormant will not provide control. Glyphosate, being a non-selective herbicide, will kill desirable lawn grasses as well.