Summer Amicarbazone Applications Control Tall Fescue In Bermudagrass.

Amicarbazone is a new selective herbicide for use in warm and cool-season turfgrasses but applications are restricted to spring in the southern U.S. due to injury concerns on cool-season turfgrasses.  Sensitivity of cool-season turfgrasses, such as tall fescue, to summer applications could allow bermudagrass managers to selectively control these species.  To test this hypothesis, field experiments were conducted in Griffin, GA to evaluate efficacy of single and sequential amicarbazone applications in summer to control tall fescue in a bermudagrass lawn.  Single and sequential applications of amicarbazone at 0.2 kg a.i./ha provided poor control (<70%) of tall fescue.  Single and sequential applications of amicarbazone at 0.4 or 0.6 kg a.i./ha provided good (80 to 89%) to excellent (90% or higher) tall fescue control and were similar to single applications of trifloxysulfuron at 0.03 kg a.i/ha and simazine at 2.2 kg a.i./ha.  Bermudagrass was not injured from any treatment.  Overall, summer applications of amicarbazone at high rates (0.4 to 0.6 kg a.i./ha) appear to have potential to control tall fescue in bermudagrass.