Atrazine is a common herbicide that acts as both a pre-emergent (kills weeds before they sprout) and post-emergent (kills mature weeds) weed control. Not only does Atrazine kill most weeds, but it also kills most grasses. This is great for controlling pest grasses but is harmful to many species of turfgrasses. Before you apply Atrazine in your yard, make sure it will kill the weeds present and leave your lawn unharmed.
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Common Weeds Atrazine Kills
Atrazine kills many of the most common weeds found in North American lawns and gardens. If you aren’t sure if Atrazine will kill the weeds in your yard, consult manufacturer guidelines. Some other, rarer, weeds may also be killed by Atrazine. The following broadleaf weeds are killed by Atrazine:
- Gripeweed (Phyllanthus)
- Dollar Weed (Pennywort)
- Florida Betony
- Morning Glory
Atrazine has been shown to be effective against several hard-to-kill weeds, such as Doveweed and Dollar Weed. If Roundup and other weed killers fail, Atrazine has a high chance of success.
Common Pest Grasses Killed by Atrazine
The active ingredient Atrazine was originally formulated as a broad-spectrum weed control for agricultural use (specifically for corn crops). It kills most grasses as well as most broadleaf weeds. The following common invasive grasses are killed by Atrazine:
- Poa Annua (Annual Bluegrass)
- Barnyard Grass
While Atrazine has been shown to be successful at suppressing crabgrass, it is not the best herbicide for killing crabgrass. If you want to kill crabgrass in lawns, try a specialized product for crabgrass control instead.
Is Atrazine Safe for Grass?
Before you apply Atrazine to your lawn, make sure you know what grass species are present. In addition to weeds and pest grasses, Atrazine will kill most species of desirable turfgrass. This makes Atrazine a very specialized-use herbicide in residential lawns.
Atrazine-Safe Lawn Grasses
Use Atrazine only on the following grasses.
- Centipede Grass
- St. Augustine Grass
Other grasses, including Bluegrass, Ryegrass, Bermuda grass, and Fescue will be killed by Atrazine. Not only that, but these grasses may fail if replanted or seeded for up to 12 months after Atrazine has been applied. If your lawn isn’t 100% Centipede Grass or St. Augustine, don’t use Atrazine.
Can You Use Atrazine to Kill Bermuda Grass in St. Augustine Lawns?
Many homeowners in the south battle against invasive Bermuda grass in their St. Augustine lawns. Atrazine is an excellent solution to this problem. It kills Bermuda grass but won’t harm your St. Augustine. Not only will Atrazine kill existing Bermuda grass, but it will also stop any Bermuda seeds from sprouting for up to 6 weeks.
If you’re tired of battling Bermuda in a St. Augustine yard, apply Atrazine to wipe out the pest and keep the grass you want.
On the other hand, do not use Atrazine on your lawn if plan to overseed your St. Augustine with Bermuda.
Is Atrazine Safe for Garden Plants?
Originally, Atrazine was designed for safe use on corn crops. It was formulated so that a wide range of invasive plants and grasses would be suppressed and killed. Because it is such an effective broadleaf plant killer, Atrazine is not safe for use on shrubs, bushes, trees, vegetable plants, or flowering ornamentals.
Do not apply Atrazine to garden plants. It will cause serious harm and in most cases will kill them. When spraying Atrazine in your yard, make sure to direct the spray onto weeds growing in your Centipede or St. Augustine yard.
How Long for Atrazine to Work?
Practice patience when applying Atrazine to lawns. It is a slow-acting herbicide that provides full results in 4–6 weeks.
While some weed controls may provide initial results in hours and complete results in 2 weeks, Atrazine may require three times as long to fully penetrate plant systems and kill tough weeds. Do not reapply Atrazine if you don’t see an immediate impact. Wait until at least 6 weeks have passed.
Although Atrazine works slowly, it is one of the best weed killers for Centipede and St. Augustine yards because it is one of the only herbicides effective against resilient warm-region broadleaf weeds such as Doveweed and Oxalis.
How to Use Atrazine for Best Results
When it comes to powerful weed control, Atrazine is one of the best products on the market. It stops weed seeds from sprouting and kills weeds that are already present. Still, there are ways to make sure you use Atrazine to maximize its effectiveness:
- Apply when the daytime temperature is 55–85℉.
- Apply in late spring/early summer when weeds are still young.
- Apply Atrazine no more than 2 times per year (a spring application and fall application).
- Dilute Atrazine according to the product label to ensure correct application rates.
- After application, allow Atrazine to dry before allowing pets and children on the lawn.
By following these guidelines you will encourage Atrazine to kill the highest percentage of weeds while also keeping your lawn healthy and protecting people and animals. By applying Atrazine in optimal conditions, you eliminate the need for repeat applications, saving yourself time and money.
What Weeds and Grasses Does Atrazine Control?
A single application of Atrazine at manufacturer rates will kill a wide variety of broadleaf weeds and pest grasses. Atrazine, the active ingredient in the herbicide, is extremely effective in keeping areas weed-free because it both kills visible weeds and prevents their seeds from sprouting.
Most pest grasses are also killed by Atrazine. This includes Foxtails, Annual Bluegrass, invasive Bermuda, Quackgrass, and Wire Grass. While Atrazine will suppress Crabgrass by stopping seeds from sprouting, it is not particularly effective at killing crabgrass plants.
Use Atrazine as weed control only in St. Augustine and Centipede Grass lawns. Atrazine is harmful to all other grass types. When used correctly, Atrazine is an incredible tool for controlling weeds in your warm-season grass lawn.