EPA Registration: 100-1267
Active Ingredient: Mesotrione – 40%
Product Use Information:
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. Tenacity may cause temporary whitening of turfgrass foliage. In general, symptoms appear five to seven days after application and last for several weeks. A repeat application to the same site causes less whitening of the plant tissue. Tenacity is an effective herbicide for weed control prior to or during seeding of certain turfgrasses during turf renovation (see section on use in New Seedings). If used preemergence in established turf, tank mixtures with
preemergence herbicides such as Barricade 65WG Herbicide are recommended for longer residual and broad spectrum weed control.
Preemergence Application – Apply Tenacity at 4-8 fl. oz. per acre in at least 30 gallons of water per acre prior to weed seed germination. Do not exceed 5 fl. oz. per acre per application to perennial ryegrass or fine fescues or mixed stands that contain greater than 50% perennial ryegrass and/or fine fescue. Do not exceed 4 fl. oz. per acre to St. Augustine grass sod. Make application close to anticipated weed seed germination. Tenacity should be combined with a preemergence herbicide such as Barricade 65WG Herbicide for extended control of key annual
monocot weeds such as crabgrass and foxtail. In established turf, Tenacity is more effective as a postemergence application unless combined with another soil active herbicide.
Postemergence Application – Apply Tenacity at 4-8 fl. oz. per acre in at least 30 gallons of water per acre. Apply with a NIS type surfactant. A repeat application at two to three weeks may be required for adequate weed control. Weed control is most effective on young, actively growing weeds. Efficacy will be reduced under moisture stress or from applications to mature weeds.
Tenacity Use Sites:
Tenacity may be used for weed control in turfgrass species listed on this label in commercial and residential sites. Use sites include non-crop areas: golf courses, sod farms, athletic fields, parks, residential and commercial properties, cemeteries, airports, and lawns. Do not use on golf course putting greens and maintain a five-foot buffer between treated areas and putting greens.
General Use Precautions:
• Do not apply more than 16 oz. of Tenacity per acre per year or per crop (equivalent to a maximum of 0.50 lb. of mesotrione per acre per year), whichever is shorter.
• Do not plant any crop other than turfgrass species for 18 months after the last application of Tenacity or injury may occur.
• Do not apply an organophosphate or carbamate insecticide within seven days of a Tenacity application as turf injury may occur.
• Do not apply through any type of irrigation system.
• Do not use aerial application to apply Tenacity.
• Do not use grass clippings from treated turf as mulch around trees or in vegetable/flower gardens.
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.• Tenacity has been tested in tank mixtures with Barricade 65WG Herbicide (prodiamine), Vanquish® (dicamba), Turflon ester (triclopyr), Spotlight™ (fluroxypyr), Quicksilver™ (carfentrazone), Basagran® (bentazon), Princep® (simazine), and AAtrex (atrazine) for safety and efficacy on turfgrasses. Tenacity must be applied at reduced rates (4 fl. oz./A or less) if tank mixed with atrazine, bentazon or simazine. Other tank mixture partners may be safe but have not been tested. Turf managers wanting to tank mix Tenacity with other herbicides should test on a small basis for compatibility, safety and efficacy before treating large areas. See product labels for directions and precautions.
• Bentgrass, Poa annua, kikuyugrass, zoysiagrass, seashore paspalum and bermudagrass are sensitive to Tenacity applications. Avoid spraying these turf types unless control and/or injury can be tolerated. Maintain a five-foot buffer between treated areas and bentgrass or Poa annua greens.
• Clean sprayer thoroughly after an application of Tenacity if same equipment is used to apply products to bentgrass and bentgrass/Poa annua turf areas.
• To reduce movement into sensitive species such as bentgrass, keep people and pets off treated areas until spray has dried and irrigate lightly to move product from turf foliage before resuming normal irrigation.
• Avoid over-spray or drift of spray applications onto ornamentals or flower beds and gardens. Roses and daylilies are sensitive plant species.
• Avoid applications over the top of exposed roots of trees and ornamentals.