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Tenacity is a systemic preemergence and postemergence herbicide for the selective contact and residual control of weeds in turfgrasses. When applied preemergence, 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 postemergence, susceptible weeds absorb Tenacity 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 postemergence weed control. A non-ionic surfactant should be added in postemergence applications.
| Active Ingredient: | Mesotrione 40% |
| For use in: | Kentucky Bluegrass, Centipedegrass, Buffalograss, Tall Fescue, Perennial Ryegrass, Fine Fescue, St. Augustine Grass |
| Coverage Area: | 5 to 8 fluid ounces per acre |
| Manufactured By: | Syngenta |
Product Documents
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.
18 of 18 people found this review helpful:
Tenacity Herbicide
By Frank on May 7, 2012I 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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14 of 15 people found this review helpful:
Appears to be working!!!!!!!!!!!!
By Del on June 17, 2012I was skeptical about whether Tenacity could kill the Nimblewill in my lawn and still leave my Blue Grass and Fescue alone. It's been 2 weeks since the first application and it appears to have definitely wounded the Nimblewill. The second application was applied yesterday, so we'll see if it kills it or not. It's a "pricey" chemical, but is easy to use and hopefully effective. If it works it sure beats Roundup and reseeding.
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7 of 7 people found this review helpful:
Tenacity Herbicide
By Paul on July 15, 2012Applied Tenacity to eradicate nimblewill about 10 days ago. The weed is turning white and dying as represented. I am very encouraged, as the weed was overtaking an otherwise decent lawn.
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7 of 7 people found this review helpful:
A Miracle Herbicide!
By Margaret on August 14, 2012I 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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6 of 6 people found this review helpful:
Slow but sure...
By Dan on August 9, 2012Don't expect results immediately. I used Tenacity with a surfactant. I wasn't sure at first if the herbicide worked. After about a week, the Nimblewill started to turn white. None of the surrounding grass seems to have been harmed. Great product!
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5 of 5 people found this review helpful:
No more Crabgrass!!
By Rob on August 23, 2012This 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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4 of 4 people found this review helpful:
Tenacity
By Nick on August 20, 2012After trying everything to try and get rid of nimberwill in the yard, I was just about to use another application of roundup when I discovered Tenacity. So far it seems to be working and is very effective on crabgrass as well.
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3 of 3 people found this review helpful:
Great product! Does exactly what it advertises!
By Debi on September 7, 2012My 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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3 of 3 people found this review helpful:
Obvious it's working...
By William on August 15, 2012Lawn was overrun with a variety of weeds (bermudagrass, Nutsedge, clover). Applied at the higher rate (8 oz. per acre but converted down for residential lawn size) as directed, putting a little extra directly on problems spots. Day Four: Noticed large weed patches turning a bright green Day Seven: Weeds turning white and some turning brown, curling and clearly dying. Good fescue grass appears unaffected and fine.
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3 of 3 people found this review helpful:
TENACITY HERBICIDE
By Rob on September 23, 2012I have used tenacity in several situations, and overall, it has been fairly effective. I originally purchased it to control nimblewill, post emergence. It was only moderately effective, although I think the nimblewill already had too much of a head start. The mature nimblewill did have white leaves, but I did not see any effect on the plant growth (or death). It has been effective against crabgrass, also post-emergent. I have also used it against Japanese Knotweed, post heavy injections into the stems with Roundup concentrate, on the regrowth after 3 doses of the above. There has been whitening of some leaves, but I have only today retreated this patch of one of the worst weeds I have ever seen. I am hopeful that the 2nd treatment will be more effective than the 1st one. By the way, my wife really didn't like the white patches in the lawn!
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2 of 2 people found this review helpful:
Tenacity herbicide
By Bill on September 18, 2012I'm not sure I used the right dilution. Instructions only cover one acre. How about mixing in oz/teaspoons per gallon for hand sprayer. I used a little over one teaspoon/gallon. Have soon no results but maybe I'm too impatient. Can you help?
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August 9, 2011William from Springfield, Il. asked:
QHow much Tenacity do you mix in a one gallon sprayer?
AAccording to the Tenacity product label you will need to mix 1/2 tsp of product + 1 1/2 tsp surfactant with 1 gallon of water for spot treatments
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October 11, 2011Mary from Marshfield, Wi asked:
QDo I need to keep the dogs away from the area where I have applied Tenacity?
AYou 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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March 8, 2012Scott from Grosse Ile Michigan asked:
QAfter applying Tenacity and surfactant how long do you have to wait to seed or sod?
AAccording to the Tenacity product label "Apply Tenacity at 5-8 fl. oz. per acre in at least 30 gallons of water per acre prior to seeding or post seeding of tolerant turfgrass species listed on this label, except fine fescue. Tenacity may reduce density of fine fescue seedings. Tenacity can be used on grass seed blends that contain less than 20% by weight of hard or fine fescue. Tenacity will control many monocot and dicot weeds that compete with and slow the establishment of the turfgrass stands. Apply at grass seeding or close to seeding for best performance. Avoid spraying on newly germinated turfgrass plants. Wait until the newly germinated turf has been mowed two times or four weeks after emergence (whichever is longer) before making a postemergence application." If you need more specific information on a turfgrass not mentioned on the product label you can reach the manufacturer at 866-796-4368.
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August 18, 2011R.bevans from Lasalle, Colorado asked:
QWhat is the chemical tenacity? supposedly they put on lawn as a post crabgrass killer.
ATenacity is a systemic preemergence and postemergence herbicide for the selective contact and residual control of weeds in turfgrasses. Tenacity contains the active ingredient Mesotrione.
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January 15, 2012Lea from Melbourne, Victoria, Australia asked:
QCould you please confirm that Tenacity will not kill of Tall Fescue or any other grasses?
Is Tenacity available in Australia, Melbourne
A 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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February 28, 2012Alphonse from Austin, Texas asked:
QCan I use Tenacity on Buffalo and St. Augustine grass?
ATenacity is labeled for use in both St. Augustine grass and Buffalo grass. Be sure to read and follow the Tenacity product label for best results.
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April 13, 2012Janet from Weston Ct asked:
QHow much concentrated Tenacity do I need to cover one acre?
AThe instruction label for Tenacity calls for 5 to 8 ounces of Tenacity per Acre. Please see page 8 of the product label for the amount per acre depending on the type of grass that you have.
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July 18, 2012Bill from Coventry, Ri asked:
QHow long must you wait after applying Tenacity Herbicide before watering the turf?
ATenacity must be watered in so you can irrigate the turf immediately after applying the product. Please refer the Tenacity product label for complete usage instructions.
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April 25, 2012Kyle asked:
QIf Tenacity is applied to a pasture how long do you need to wait before allowing grazing?
AWe contacted the manufacturer Syngenta since Tenacity is not labeled for use on pasture land and they told us that you would need to wait 90 days before turning animals out to graze in treated pastures.
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August 24, 2012Chuck from Dekalb, Ill asked:
QHow long should you wait before retreating your grass? It has been 2 weeks since I first applied. I can see
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
AAccording to the Tenacity product label you can reapply the product after 2-3 weeks for post emergence control of actively growing weeds for best results.
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July 23, 2012Roland from York, Pa asked:
QWill Tenacity control Nutsedge grasses?
ATenacity is labeled for control of Yellow Nutsedge grass only. Tenacity does not cover other species of nutsedge. We do carry Sedgehammer which was specifically formulated for nutsedge control.
December 29, 2012Jim from Keizer,oregon asked:
QI am in Oregon with Green Perennial ryegrass. At what time of year do I start with my first application.
My personal lawn. Was hydroseeded and slowly has been invaded with crabgrass and other grassy weeds.
ATiming will vary greatly from region to region. We recommend contacting your local cooperative extension office and speaking to the master gardener on staff as he/she will have the most accurate timing information available for your region.
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April 3, 2013Larry from East Greenwich ,rhode Island asked:
QIn a 5000sq. ft yard. How much Tenacity per gallon of water do I need to treat this area?
AAccording to the Tenacity product label for smaller applications you will need to mix 0.5 tsp of Tenacity, 1.5 tsp of surfactant to one gallon of water and each gallon of solution needs to cover 1,000 sq ft.
