Tenacity Herbicide: What It Kills, Rates & Where To Buy

Tenacity Herbicide

Tenacity is Syngenta’s mesotrione herbicide and one of the most useful bottles a cool-season lawn owner can own. It works as both a pre- and post-emergent on crabgrass, clover, dandelion and creeping bentgrass, and it’s one of the few weed killers you can put down on the day you seed.

Active ingredient

Mesotrione 40%

Best for

Weed control at seeding; bentgrass and young crabgrass

Rate

4–8 fl oz per acre (label); per-1,000 sq ft mix in our calculator

Lawn types

Kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue, centipede

Where to buySold by Solutions Pest & Lawn.

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Bottle of Tenacity mesotrione herbicide — Plate · Tenacity

Tenacity, the mesotrione herbicide we use at seeding and on bentgrass.

What it’s for

Tenacity controls over 40 broadleaf and grassy weeds, including crabgrass, dandelion, clover, chickweed, purslane and yellow nutsedge. Its standout uses are two jobs few other products can do: keeping weeds out of a fresh seeding, and taking creeping bentgrass out of a bluegrass or fescue lawn.

In our Tenacity review, our author sprayed it in August on bentgrass after dethatching and saw a clear improvement after two applications. Used at seeding without surfactant, it gives roughly 30 days of pre-emergent control while the new grass comes in.

How to use it

The label rate is 4–8 fl oz per acre in at least 30 gallons of water. That’s a tiny amount per 1,000 sq ft, so use our Tenacity calculator to get the exact mix for your lawn size and for pre- or post-emergent use.

For weeds that are already up, add a non-ionic surfactant to help it stick. Leave the surfactant out when you spray at seeding. Expect treated weeds to turn white within about 5–7 days, and repeat in 2–3 weeks for tough weeds, per the label. Our rainproof guide covers how long it needs before rain.

Watch out for

Injures bentgrass, Poa annua, kikuyu, zoysia, seashore paspalum and bermudagrass. It can bleach your good grass for a short time; the white tips mow off. Avoid spraying above 85°F, during drought, or within two weeks of aerating.