Friday, October 26, 2007

Turf - Mesotrione a New Turf Herbicide to be Released as "Tenacity"

All photos from the presentation "Mesotrione for Weed Control in Warm- and Cool-Season Turf" by Travis W. Gannon, Fred H Yelverton, and Leon S. Warren, North Carolina State University, Department of Crop Science. To view the full presentation go to

Mesotrione is the common chemical name for a new herbicide to be released this winter as Tenacity. This will be a great material, giving good control of many problem weeds in turf. The following is an article on the subject. (currently, Tenacity is only labeled on golf courses and sod farms).
  • Mesotrione is a new herbicide that will be registered soon for use in turf. Originally to be called Outplay, Syngenta has changed the proposed name to Tenacity. It is due to be released this winter pending registration approval.

  • Mesotrione is a pigment inhibitor type herbicide (turning weeds white) that will have many uses for weed control in cool season turf. It has excellent safety on tall fescue, perennial ryegrass, and Kentucky bluegrass.

  • With annual grass weeds, mesotrione is highly active against crabgrass both pre and post emergence, has shown the ability to control goosegrass at higher rates, and is active on annual bluegrass as a fall treatment pre and post emergence.

  • What is noteworthy is that mesotrione can suppress or control certain weedy perennial grass species including nimblewill and creeping bentgrass in cool season turf.

  • Another problem weed controlled by mesotrione is yellow nutsedge.

  • Mesotrione has activity against many broadleaf weeds such as chickweed, henbit, plantain, and oxalis. It has good activity on dandelion and fair activity on clover. However, when combined with triclopyr (Turflon), clover control is excellent.

  • Another feature of mesotrione is its safety on new turfgrass seedings. Research in New Jersey has shown that it can be used safely as a preemergence herbicide on new seedings. There is some risk of injury with early postemergence applications in the first 3 weeks of seedling growth, especially at higher rates so it is best used preemergence (after seeding but before emergence).

Gordon Johnson, Extension Agent, Commercial Horticulture, UD, Kent County

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