Turfgrass - Tenacity Herbicide Currently Only Labeled for Golf Courses and Turf Farms

There has been considerable interest in mesotrione as a turfgrass herbicide because of its wide and unique weed spectrum. While it has received registration as Tenacity, it is currently only labeled for golf courses and sod farms. If additional labels are received or the label is expanded, we will inform you. You can acces the current label through the Syngenta web site at http://www.syngentacropprotection.com/pdf/labels/SCP1267AL11207.pdf

Gordon Johnson, Extension Horticulture Agent, UD

Turfgrass - Tenacity Herbicide (mesotrione) Now Available

Mesotrione, the active ingredient in the new turf herbicide, Tenacity, has a wide range of activity on turf weeds and will give us a tool to control some of our difficult weeds. It received registration over the winter and is now available but only for use in golf courses and turf farms. A residential turf label is expected later in 2008. The following is some information on this herbicide.

Mesotrione the active ingredient in a new herbicide that is registered now for use in turf. Syngenta has named the herbicide Tenacity. 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 Horticulture Agent, UD, Kent County

Turf - Tenacity (mesotrione) Herbicide for Crabgrass Control and for use at Establishment

Tenacity herbicide has the active ingredient Mesotrione. It will give some very good options for controlling hard to kill weeds in turfgrass. The following are some slides on its use for controlling crabgrass and at turf establishment. Currently it is only labeled on golf courses and sod farms.

From a presentation by Dr. Steve Hart, Rutgers University.

Turf - Tenacity Herbicide (Mesotrione) for the Control of Bentgrass and Nimblewill in Cool Season Turf

Tenacity herbicide with the active ingredient mesotrione will give control of bentgrass and nimblewill in cool season turfgrass. The following are some slides on these uses. Currently Tenacity is only labeled on golf courses and sod farms.

From a presentation by Dr. Steve Hart, Rutgers University

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 http://www.turffiles.ncsu.edu/extension/presentations/2006/Mesotrione_WeedControl.pdf

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

Ornamentals Hotline Weed Pictures for Issue 26, October 12, 2007

Mesotrione effect on crabgrass and nutsedge.

Mesotrione effect on plantain and Oxalis.

Control of crabgrass with mesotrione in turf.

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 http://www.turffiles.ncsu.edu/extension/presentations/2006/Mesotrione_WeedControl.pdf