How do herbicides like Roundup work?

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How Does the Herbicide Roundup® Work?

Roundup®, which is a trade name used by Monsanto, and other herbicides based on Glyphosate, which is the generic name, are probably the most commonly applied weed killers in use today. These herbicides are used by everyone from farmers to foresters, to gardeners, to biologists who are trying to control invasive exotic plants. Glyphosate-based herbicides all work on the same biochemical principal. They inhibit a specific enzyme that plants need in order to grow. This specific enzyme is called EPSP synthase. Without that enzyme, plants are unable to produce other proteins essential to growth so they yellow and die over the course of several days or weeks. The majority of plants use this same enzyme, so almost all plants succumb to Roundup®.

If you’ve read the How Stuff Works article called How Cells Work, you know a good bit about DNA, and how it produces enzymes. In the same way that many antibiotics gum up enzyme production to kill bacteria, Glyphosate gums up enzymes in plants to kill them. Glyphosate kills plants like antibiotics kill bacteria. If you’ve been following farming news or the genetically modified food debate, you know that Glyphosate tolerant seeds are now available. You can buy genetically modified corn, soybeans and so on that are immune to Glyphosate. These plants use an enzyme that performs the same function as EPSP synthase, but is not inhibited by Glyphosate.

Roundup® will kill almost any plant including aquatic plants, so you want to be sure to avoid spray drift onto other plants, or into the water. Any pesticide should be applied carefully.

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