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How Long Does It Take For Atrazine To Work

Atrazine is a selective systemic herbicide in the triazine class that is designed to target grass and broadleaf weeds after a crop or tree has emerged. It is one of the most widely used herbicides that has been most effective with crops like corn and grain sorghum.

Because Atrazine is used to kill weeds among crops, it is primarily used in large areas. Studies have shown that it can increase crop yields by 6% and help reduce soil erosion.

As great as this pre-emergent herbicide is and its many significant benefits, it has been found to dissolve into the water sources nearby.

Though Atrazine is a very popular herbicide, it is also one of the most contested and controversial in the world.

The way Atrazine works is by absorbing into the roots of weeds, working its way up into the leaves and main developmental areas, and inhibiting photosynthesis.

Here is a great educational video was done by University at Buffalo, the State University of New York that was supported by the NSF (National Science Foundation).

The video discusses the geographic reach of Atrazine, how it works on a chemical level. It’s a scientifically educational video that explains how Atrazine works inside of a plant.

On average, it takes about 14 to 21 days for the herbicide to take effect.

Though Atrazine is an effective herbicide that continues to work for a few months, it is suggested that it be applied to fields twice a year.

The first time you should spray Atrazine is around January before weeds have had a chance to establish roots and again around November when crops have been harvested, and any weeds that have survived are going dormant for the winter.

It's pretty clear to see why this is such a popular herbicide. It kills rather quickly, helps keep soil intact, and doesn't kill the crops. From an aerial view, Atrazine seems like the perfect herbicide, but as I mentioned earlier, it is a heavily contested product.

Atrazine is so widely contested because it has been known to enter water sources and, over time, has proved harmful to smaller creatures: frogs, birds, bees, and others. However, despite these small findings, the EPA has not called for a suspension of the chemical.

You may be wondering why a chemical that has been found to have a negative impact on the ecosystem is still so widely used. Well, let’s take another look at it.

The likely reason for the continued use of Atrazine after a few disturbing discoveries is that nothing has been found that puts humans in any real danger.  That being said, that doesn’t mean that there aren’t risks or undiscovered dangers.

And don’t think for one second that medical authorities aren’t still looking for a reason to take it off the shelves, they just have yet to find anything that will stick. However, after extensive research when it was first released and again in the early 2000’s, studies didn’t find anything to push for suspension.

Here are some little-dated facts about Atrazine’s public life:

  • 2001: The most common pesticide detected to be contaminating drinking water in the USA.
  • 2003/4: Atrazine was banned in the EU (European Union)
  • 2006: the EPA ruled that Atrazine was safe to use after reviewing over 6,000 studies, and over 80,000 public comments
  • 2007: the EPA said that there were no adverse effects on the sexual development of amphibians
  • 2009: the EPA went back a bit on their 2006 ruling and ruled that Atrazine was indeed more hazardous than initially thought, but still allowed it to be sold.
  • 2011: a federal Agricultural Health Study discovered that there were no consistencies between cancer in farmers and their families who lived in close proximity to where Atrazine was applied. This study began in 1993.
  • 2014: Listed as the 2nd most widely used herbicide in the USA.

Atrazine has only really been shown to cause genetic damage to amphibians (EPA believes this to be true) and in particular, higher concentrated areas, impact small avian animals and insects. However, this herbicide has shown very low toxicity to mammals. Humans are mammals, and rather large mammals at that, our exposure before symptoms would have to be extreme.

The study that found Atrazine to impact mammals was discovered in late 2003 by the ATSDR (Agency for Toxic Substances and Disease Registry).

As always, agencies like the ATSDR are worried that a chemical is causing cancer, so they studied more. They did find that Atrazine can affect a person’s reproductive system function. They studied couples living close to where Atrazine is used and found that there was an increased risk of preterm delivery. However, this study seems incomplete and unresolved.

As with all things in science, for any hypothesis to be proven as fact, the results must be replicated by other studies, and this has yet to be done. So, the EPA can only say and do so much based on any minimally tested hypothesis.

Until Atrazine has been proven to be a real hazard to the environment, humans, animals, and the entire ecosystem, I’m sure it will stay on shelves and continue to be widely used throughout the world.

If you’re looking to use Atrazine, you can find products that contain it in most home center and gardening centers in your town.

I do caution you….if you are going to use Atrazine to eliminate those stubborn weeds, READ AND FOLLOW THE LABEL'S instructions for mixing and use. And don’t spray it in or near a water source.

About the author

    Matt Hagens

    Hi, I'm Matt the owner of Yard Care Gurus. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Thanks for stopping by!

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