Frequently asked questions concerning Tenacity™ herbicide.

The following are many of the most frequently asked questions about Syngenta's newest product, Tenacity™ herbicide. If you have a question not on this list, please feel free to contact your Syngenta territory manager.

What makes Tenacity different than other currently used turf herbicides?

Tenacity is a selective, systemic herbicide that features a new mode of action for pre- and post-emergence grass and broadleaf weed control in several cool- and warm-season turf species—like keeping bentgrass out of your rough. Tenacity can also be applied on established or newly seeded turf.

What is the active ingredient in Tenacity herbicide?

Mesotrione is the active ingredient in Tenacity herbicide.

How was Tenacity herbicide discovered?

A Syngenta scientist in California noticed that there were fewer weeds growing under his bottlebrush (Callistemon citrinus) plant, far fewer than can be explained by shading alone. He concluded that the plant must be producing allelochemicals to suppress weed competition. Syngenta synthesized mesotrione based on the allelochemicals produced by the bottlebrush plant.

What is the mode of action of Tenacity herbicide?

Tenacity inhibits a plant enzyme called HPPD that is essential to photosynthesis and prevents formation of carotenoids in susceptible plant species. Without carotenoids, light energy and by-products of photosynthesis will destroy chlorophyll and cell membranes. This results in bleaching of leaves followed by necrosis and death of the plant.

How quickly does Tenacity work?

Once absorbed, Tenacity quickly translocates throughout the plant. Weed growth is suppressed soon after application, as photosynthesis is disrupted. Death of the plant usually occurs within two to three weeks.

What turf species can Tenacity be applied to?

Tenacity can be applied to many of the cool-season turf types commonly found on fairways and roughs, such as Kentucky bluegrass, perennial ryegrass, tall fescue, fine fescue, centipedegrass, and St. Augustinegrass (sod only). Lower use rates are recommended for perennial ryegrass, fine fescue, and St. Augustinegrass. Tenacity is not for use on putting greens and tees.

What are some of the unique benefits of Tenacity herbicide?

Tenacity has pre- and post-emergence activity on 46 dicot and monocot weed species. It can selectively control perennial monocots such as bentgrass and nimblewill and annuals such as crabgrass and goosegrass in many turfgrass species. Tenacity can be applied at the seeding to prevent weed germination and allow the turfgrass species to establish without weed competition.

Can Tenacity be used to get bentgrass out of roughs and fairways?

Yes. Tenacity selectively controls bentgrass out of Kentucky bluegrass, perennial ryegrass, and tall fescue turf.

What does it mean that Tenacity was granted reduced-risk status by the EPA? Why did Tenacity earn this status?

Reduced-risk is an EPA designated registration status that accelerates the process for registration of certain new plant protection products. Tenacity received reduced-risk status by the EPA based on its unique mode of action, low use rates, and favorable toxicity and human health profiles, as compared to other herbicides currently on the market.

On which grasses has Tenacity been tested for use at or prior to seeding?

Tenacity is safe for use at or prior to seeding on Kentucky bluegrass, tall fescue, perennial ryegrass, and centipedegrass. Application at seeding can be made to fine fescue only if it is less than 20% of a seed mixture.

Are there any grasses on which you can't use Tenacity?

Tenacity is not recommended for use on zoysiagrass, hybrid or common bermudagrass, seashore paspalum, or kikuyugrass.

Can Tenacity be tank mixed with other herbicides?

Tenacity can be tank mixed with Barricade®, dicamba, carfentrazone, triclorpyr, atrazine, simazine, s-metolachlor, bentazon, and several three-way phenoxy herbicides. Combinations can help turf managers broaden the weed control spectrum or improve the level of weed control over single-product applications.

How rainfast is Tenacity?

Tenacity is rainfast within several hours under normal rainfall conditions.

What other brands currently on the market offer a product similar to Tenacity?

There are currently no other herbicides like Tenacity for golf courses and sod farms registered for use or sale in the U.S. Tenacity will compete with multiple products from different classes of chemistry.

Will purchasers receive GreenPartners® points for Tenacity purchases?

Yes. Please contact your Syngenta territory manager for more information.


©2008 Syngenta Crop Protection, Inc., P.O. Box 18300, Greensboro, NC 27419. Important: Always read and follow label instructions before buying or using this product. Tenacity™ is not currently registered for use in all states. Please check with your state or local extension service prior to buying or using this product. Tenacity™ and the Syngenta logo are trademarks of a Syngenta Group Company.

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