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Average Rating

4.5 out of 5 stars Rating: 4.3

594 Reviews | 611 Q&A

Product Overview

Tenacity Herbicide is a systemic pre-emergent and post-emergent herbicide for the selective contact and residual control of weeds in turfgrasses. Tenacity can be used for weed control prior to or during seeding of certain turfgrasses during renovations. When applied as a pre-emergent, weeds absorb Tenacity during emergence from the soil. Dry conditions following application may reduce the pre-emergence activity. If rainfall (0.15 inches) has not occurred within 10 days after a pre-emergence application, activate with 0.15 inches of irrigation.  When used as a post-emergent, Tenacity weed killer is absorbed by susceptible weeds through foliar contact and soil absorption. Foliage of treated weeds cease growth after application, then turn white (loss of chlorophyll) and death may take up to three weeks. A repeat application is required after two to three weeks for improved post-emergence weed control. A non-ionic surfactant should be added in post-emergence applications.

We also offer the Tenacity Herbicide Kit with Surfactant and Spray Indicator Dye which includes one 8 ounce bottle of Tenacity Herbicide, one 32 ounce bottle of Turf Mark Blue Spray Indicator Dye, and one 8 ounce bottle of Hi-Yield Spreader Sticker Non-Ionic Surfactant.


  • Tenacity is NOT for use on Bermudagrass when actively growing or St Augustine home lawns.
  • Tenacity does NOT provide post-emergent control of Poa Annua.  It will only provide suppression of Poa Annua when used as a pre-emergent.  
  • When treating for clover, or suppression of bermudagrass, it is recommended to tank mix Tenacity Herbicide with Turflon Ester for more improved control.  Please see Supplemental Label 2(ee) for complete instructions.   This 2(ee) Recommendation applies to the following turf species only: Tall fescue, Kentucky Bluegrass, and Perennial Ryegrass.

Syngenta has recently updated its Tenacity packaging.  You may get either the new packaging or the old packaging until all of the old packaging style has been depleted.  There is no change to the product itself, only the exterior packaging.  

Features and Specs

Active Ingredient Mesotrione 40%
Target pests Barnyardgrass, Carpetweed, Chickweed, Clover, Crabgrass (large & smooth), Dandelion, Foxtail, Goosegrass, Henbit, Yellow Nutsedge, Purslane, Thistle, Wild Carrot and others
* See label for complete list
For use in Kentucky Bluegrass, Centipedegrass, Buffalograss, Tall Fescue, Perennial Ryegrass, Fine Fescue, St. Augustine Grass (grown for sod only)
Application 4 - 8 oz. per 30 gallons of water per acre
* Use a Surfactant to Increase Effectiveness
* See label for complete application instructions
Formulation Professional Product
Group 27 Herbicide
Shelf Life 3-5 years from date of manufacture when properly stored. Keep out of direct sunlight and extreme temperatures
Shipping Weight 0.81 lbs
Manufacturer Syngenta (Mfg. Number: 46256)
EPA Registration 100-1267



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.

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 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.

Review Search   
Sort Reviews
  • 5 of 5 Stars

    Tenacity Herbicide

    By Frank on 05/07/2012

    Verified Purchase

    I had a lot of weed grasses in my yard and they were invasive and spreading over the whole yard. Tenacity targets weed grasses and kills them while leaving the rest of the yard in tact and that is exactly what it did. All of my weeds are dying. One thing you must note is that this herbicide needs to be watered after it dries on the plant so that the plant takes it in. It will not work if you just spray it on and don't get rain or water it for a couple of weeks. It's pricy but I know of no other chemical that will kill weed grasses and leave what you want, alone.

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    602 of 629 people found this review helpful

  • 5 of 5 Stars

    A Miracle Herbicide!

    By Margaret on 08/14/2012

    Verified Purchase

    I had a lawn that was completely taken over by bentgrass. I used round up on the lawn and put in an entire new lawn. All was well for a year or two. Then the the bentgrass came back in a few isolated areas. I would have to round them up at the end of the season and reseed. This went on for a number of years. When I learned about Tenacity I was thrilled and gave it a try. It works wonderfully! Yes it is pricy, however it beats having to round up the bentgrass, clear it out, put down more top soil and reseed. Try won't be disappointed.

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    375 of 389 people found this review helpful

  • 5 of 5 Stars

    Death of Nimblewill grass

    By David on 10/02/2015

    It took a while, but the grass and other weeds are all white/dying. I used three teaspoons of "Dawn Ultra" & one teaspoon of Tenacity to two gallons of water, per a study by Ohio State University.

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    321 of 334 people found this review helpful

  • 5 of 5 Stars

    Great product! Does exactly what it advertises!

    By Debi on 09/07/2012

    My mom completely re-sodded front and back lawns and within 3 years it had been invaded by bentgrass. My new lawn was hydro-seeded 5 years ago in a new subdivision that used to be a golf course. Our methodology was to use Roundup in the fall (when the bent grass really seems to take off in growth) and then reseed the large killed off areas, hoping that the Roundup did a thorough job in killing the bentgrass. This becomes very tedious every year, not to mention the expense. We waited a few years for Tenacity to be available to the public and have both been having great results with the product. The good thing is that the remaining blades of good turf remain green in the kill zone. That gives me hope that I may not have to reseed, just wait for the good turf grass to fill in by itself. Our lawns are a combination kentucky blue and fescue blends. My only complaint is that the product is so concentrated and thick. The high concentration makes it even more critical to measure accurately! Not too crazy about the enclosed syringe measuring device. I feel it is too difficult to use and the potential to spill is high. I would love if there could be a more diluted Tenacity product to purchase for the average homeowner. That would make the product easier to measure, plus ensure a bit of wiggle room on the measurements?

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    304 of 329 people found this review helpful

  • 5 of 5 Stars

    No more Crabgrass!!

    By Rob on 08/23/2012

    Verified Purchase

    This product really works. It does take time, so be patient. I still have to apply the second application to finish off the Crabgrass!!! It won't take much, the plants are almost dead now after 2 weeks.

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    253 of 262 people found this review helpful

See all 594 customer reviews

Questions & Answers

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In one answer about watering you state it does not need to be watered in because it is mixed with water;

however, in another answer you state it does, indeed need to be watered in asap. could you please clarify which is correct. Thank you.

Tenacity is a systemic preemergence and postemergence herbicide for the selective contact and residual control of weeds in turfgrasses. When applied as a preemergent, weeds absorb Tenacity during emergence from the soil. Dry conditions following application may reduce the preemergence activity. If rainfall (0.15 inches) has not occurred within 10 days after a preemergence application, activate with 0.15 inches of irrigation. When used as a postemergent, susceptible weeds absorb Tenacity through foliar contact and soil absorption. Therefore, you should water in Tenacity when using it as a preemergent herbicide but it does not need to be watered in when using it as a postemergent herbicide.

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1255 of 1312 people found this answer helpful

How soon can I mow my lawn after an application of Tenacity?

You can mow your lawn 2 days before application of Tenacity Herbicide and 2-3 days after application. 

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960 of 985 people found this answer helpful

After spraying Tenacity Herbicide, when the weeds turn white, do you pull them or just reseed?

I was told I had nimblewill in my yard. It was a large portion with green blades and brown plus some other weeds. I purchased tenacity from you and applied it. The areas that were brown and green haven't turned white but the are scattered portions of other weeds that have. Does that mean anything? Also, am I supposed to pull them after they turn white and reseed?


After spraying with Tenacity Herbicide, the foliage of treated weeds cease growth after application, then turn white (loss of chlorophyll), and death may take up to three weeks. A repeat application is required after two to three weeks for improved postemergence weed control. We would not recommend pulling up any weeds because the product will not get into the root system, and the weeds may come back at that point.

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953 of 1032 people found this answer helpful

What is the amount of Tenacity per gallon for application on a St. Augustine lawn per 1,000 sq ft?

The label only discusses per acre application. How do you break that down per gallon in a sprayer or per 1000 sq ft application? I am using a 4 gallon backpack sprayer.


According to the Tenacity product label for smaller applications, you will need to mix 0.5 tsp of Tenacity and 1.5 tsp of surfactant to one gallon of water covering 1,000 sq ft.

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827 of 885 people found this answer helpful

Do I need to keep the dogs away from the area where I have applied Tenacity?
You should keep the dogs off of the area while you are applying Tenacity and until the area has had a chance to dry, about 2-4 hours.

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755 of 774 people found this answer helpful

See all 611 customer questions

Tenacity Herbicide 4.5 out of 5 stars Rating: 4.3 (594 Reviews / 611 Q&A)

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