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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.
PLEASE NOTE:
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.

Product Documents
| 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 |
| NOT FOR SALE TO | AK, PR |
| 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 |
Tenacity Herbicide is a professional-grade, selective weed control solution that works both before and after weeds emerge. Powered by the active ingredient mesotrione, it targets over 40 grassy and broadleaf weeds while remaining safe for many common lawn types. Its unique ability to be used during seeding sets it apart from most traditional herbicides.
Tenacity controls over 40 weed species, including both grassy and broadleaf weeds such as:
It is especially valued for controlling difficult perennial grassy weeds in turf. See the label for the full list of weeds that Tenacity will kill.
Tenacity is safe for use on many cool- and some warm-season grasses, including:
It can also be used at or before seeding these grasses. See the Tenacity label for a full list of grass types.
Do not use Tenacity on:
Using Tenacity on these grasses may result in injury or discoloration. Always read the label and follow the instructions when using an herbicide like Tenacity.
Yes. Tenacity is one of the few herbicides that can be used at or near seeding time.
Tenacity works as both a pre-emergent and post-emergent herbicide, making timing flexible:
For optimal performance:
For small, spot-treatment applications, mix 0.5 teaspoons of Tenacity Herbicide per 1 gallon of water to treat approximately 1,000 square feet.
For best results, add a non-ionic surfactant at 1.5 teaspoons per gallon to improve weed control by helping the product stick to and penetrate foliage.
Tenacity begins working soon after application:
This whitening effect is normal and indicates the herbicide is disrupting photosynthesis.
No, Tenacity does not need to be watered in when used as a post-emergent herbicide.
Tenacity Herbicide needs about 6 hours to fully dry on the plant before rain or watering. After this time, rainfall or irrigation should not reduce its effectiveness.
Tenacity stands out because it features a unique mode of action (mesotrione) that:
Currently, there are no direct equivalents with the same combination of selectivity and versatility available for residential turf use.
Yes, Tenacity can be tank mixed with other compatible herbicides to broaden weed control, including:
Always follow label instructions and perform a compatibility test before mixing.


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Tenacity Herbicide
By Frank on 05/07/2012
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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648 of 677 people found this review helpful
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A Miracle Herbicide!
By Margaret on 08/14/2012
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 it...you won't be disappointed.
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405 of 421 people found this review helpful
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Death of Nimblewill grass
By David on 10/02/2015
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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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335 of 361 people found this review helpful
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No more Crabgrass!!
By Rob on 08/23/2012
Is Tenacity available in Australia, Melbourne
Tenacity Herbicide is labeled for use on Tall Fescue, Kentucky Bluegrass, Centipedegrass, Buffalograss, Perennial Ryegrass, Fine Fescue, St. Augustine Grass. Other species of grass such as Bentgrass, Poa annua, kikuyugrass, zoysiagrass, seashore paspalum and bermudagrass are sensitive to Tenacity applications and damage may occur. According to the product label - Residential Lawn Applications: Unless renovating and/or re-seeding the home lawn, avoid broadcast applications of Tenacity for pre and post-emergence weed control because undesirable whitening of some turfgrasses may occur.
We do not ship to Australia and we are not sure if the manufacturer offers Tenacity in Australia. You can contact the manufacturer, Syngenta, to inquire about availability 866-796-4368.
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102 of 114 people found this answer helpful
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24 of 30 people found this answer helpful
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56 of 58 people found this answer helpful
the sprayed areas are turning white. Should I do another application at this time. The "bad" weed is hanging in there and I want to totally get rid of it befor winter. Thanks
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25 of 29 people found this answer helpful
My personal lawn. Was hydroseeded and slowly has been invaded with crabgrass and other grassy weeds.
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0 of 3 people found this answer helpful
I'm looking for a product that will kill Zoysia grass.
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110 of 123 people found this answer helpful
I know quackgrass is not specifically mentioned on the product label, but I have read some unscientific research saying it does control and eliminate quackgrass with repeated applications.
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10 of 14 people found this answer helpful
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6 of 7 people found this answer helpful
Every year i have problem with nutsedge weed. Can you suggest which pre- emergent is best to use.
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50 of 55 people found this answer helpful
I heard the product stays active even after composting and may harm my garden plants.
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190 of 205 people found this answer helpful
Tenacity Herbicide
Rating: 4.3 (618 Reviews / 678 Q&A)