Pre & Post Emergent: Tenacity Herbicide

Where do you get it? #

Tenacity Turf Herbicide – 8 ounces

Why should you buy it? #

Tenacity herbicide is both a pre-emergent and post-emergent you mix with water and spray. It is more of a specialty herbicide than a common one like 2,4-D based herbicides. It can kill 46+ type of broadleaf weeds. It works better as a pre-emergent for weeds than a post-emergent. Use one of the other recommended herbicides first and Tenacity only if you need it in a specific program based approach consisting of multiple applications. It is not designed for singular applications. Tenacity is seed and sod safe unlike 2,4-D so that is one of the situations where Tenacity would be a better herbicide to use.

What’s in it? #

Tenacity comes in a tiny 8 oz bottle like this with a syringe and has a 5-8 year shelf life:

It is made by Syngenta AG based in Switzerland. Syngenta AG was purchased by ChemChina (a Chinese state-owned enterprise) in 2017.

The active ingredient is Mesotrione which is based on the naturally occurring compounded by the Crimson Bottlebrush plant which is also known as the Lemon Bottlebrush plant among other names (Callistemon citrinus or Melaleuca citrina scientific names). Mesotrione acts by inhibiting photosynthesis. 40% of Tenacity is made up of Mesotrione.

Tenacity is absorbed through weed roots, shoots, and leaves and distributed throughout the plant by xylem and pholem translocation. Xylem transports water and mineral salts from the roots up to other parts of the plant, while phloem transports sucrose and amino acids between the leaves and other parts of the plant.

Once Tenacity begins to work all your weeds will begin to turn white since photosynthesis is being halted and green chlorophyll starts to go away. You typically need to apply Tenacity at least a second time around 3 weeks later for it to actually kill the weed. For really hardy weeds you may need to apply a third or even fourth time to kill it, but beware it may also impact the nearby Bermuda grass and bleach it white if you are putting down that much.

Here is the zoomed-in label for Tenacity:

Only apply Tenacity when daytime temperatures are below 90 degrees to prevent grass burn and there is no rain forecasted for 48 hours. Do not run your sprinklers for 48 hours after applying. This will ensure full absorption of Tenacity.