Not All Roundup® is Glyphosate

Article by Dr. Brett Wells Bultemeier, Extension Assistant Professor Pesticide Information Office, UF/IFAS Extension

While we at UF/IFAS Extension and the Florida Master Gardener Volunteer Program do not endorse one particular product or brand over another, this popular weed control is in the news and on the shelves. We strive to provide you with up-to-date, research based information from a source you can trust. We also recommend Integrated Pest Management (IPM) as the best strategy for weed and pest management. IPM involves the use of many different pest control options but usually recommends cultural, mechanical, and biological control options be explored before turning to a chemical control.

If you have specific questions about glyphosate, please contact Dr. Bultemeier at bwbult@ufl.edu. Please also see the resources from the Electronic Data Information Source of UF/IFAS Extension (EDIS), the U.S. Food and Drug Administration (FDA), and the U.S. Environmental Protection Agency (EPA) at the bottom of this article. And, as always, please be sure to read and follow all instructions found on the labels of products purchased for use in your landscape; the label is the law.

"Glyphosate is the largest-selling single crop protection chemical worldwide (Woodburn 2000) and the most used herbicide in the nursery industry in the United States (Norcini et al. 1996). It is used for postemergent control of vegetation." (EDIS 459)

Roundup® is one of the most widely used pesticides in the world. It is used to control troublesome weeds in areas like agriculture and aquatics, from forestry to flower beds. Roundup® has become synonymous with the active ingredient glyphosate, as this was the original molecule in the first formulations of Roundup®.

Since then the Roundup® name has become so recognized that it is now used in a wide range of products. Some of these products contain glyphosate (plus other herbicides) while others contain no glyphosate at all. This fact can make it difficult for the average consumer to select the right product. Unfortunately, choosing the wrong product, or using it incorrectly, can have severe consequences. Reading the product label before purchase and before using the product each and every time, will help ensure that the right product is being used.

Glyphosate has many attributes that make it versatile and is why it is used in so many different types of sites. Most notably it is widely effective (non-selective), controlling a varied range of weeds. Additionally, glyphosate is effective because it is a systemic herbicide, meaning it moves freely within the plant and controls the plant down to the root. This greatly limits regrowth potential and reduces the overall number of treatments. Furthermore, it is not persistent in the soil, meaning it will control what it is sprayed on, but won't stay active in the soil and control nearby desirable plants after a spray. This can be important for spraying around trees or other desired vegetation, where the foliage can be protected. Because of this, Roundup® became a favorite of homeowners and gardeners. It was the one product that could kill crabgrass in their driveway and spurge in their flowerbeds.

The versatility and popularity of this herbicide over the past 40 years has led to unprecedented name recognition. It is one of the very few pesticides that is offered for sale in almost all "big box" stores and even advertises on television. To capitalize on this popularity, companies have taken great liberty with the Roundup® name brand, expanding it to an ever-increasing number of products. There are currently 16 unique formulations of Roundup®. There can be wide differences in glyphosate percentage, ranging from concentrates to pre-diluted "ready-to-use" products. These differences can be challenging to spot and require the user to look very closely at the label to notice them.

For instance, Figure 1. shows various products that have up to an 18x difference between them, even though the labeling is so similar. Some versions have other herbicides added to glyphosate to speed up the herbicidal activity or prolong activity in the soil. Interestingly, some Roundup® products contain no glyphosate at all!

Figure 1. Nearly identical Roundup® labels. The products on the left are ready to use and have 10-18 times less glyphosate than the concentrated products on the right.

This plethora of offerings can be confusing to homeowners, as they might assume that "all Roundup® is glyphosate" and pay little attention to what they are spraying. There is clear communication on the label of each product and supporting online resources to help homeowners make their decision. Unfortunately, homeowners may not think to consult these resources since they have decades of experience with Roundup®. This could lead to performance issues and non-target damage. Knowing which product you are using, what is in it, and how strong it is all matter for ensuring the product will work as expected. The only way to ensure that the proper product is being used correctly is to read the label before purchasing the product and immediately before use of the product.

Of particular concern are products that advertise "long-lasting" or "total vegetation control." Since glyphosate is not active in the soil, these formulations have other herbicides added that will remain in the soil and active on plants for some time after spraying. This means that nearby trees could soak up these products into their roots and become damaged.

Figure 2. Damage on buttonwood and schefflera trees found in a travel plaza that was managed for weeds (Credit: Henry Mayer).

Figure 2. shows damage to a buttonwood tree that was suspected to have been sprayed with a Roundup® product containing such active ingredients. This stunted and bunched growth is typical of these herbicides. It is possible that the person spraying these tree islands simply grabbed what they thought was a glyphosate-only Roundup® product (which is safe to use in this circumstance) and sprayed as normal. Following the label precisely will reduce the chance of unintended effects and allow the product to work as intended.

Always checking a product label before you purchase and before you apply should be the routine of all pesticide users. Knowing exactly what you are buying and how to use it will ensure the greatest benefits, with a greatly reduced risk of unintended consequences. Clearly, it can be confusing to have so many Roundup® products available, especially when we often assume all Roundup® is glyphosate. Just remember, a rose by any other name might smell as sweet, but Roundup® by the same name, may not indeed be glyphosate.

For more information about specific yard pests, diagnosing pest problems, and controlling pests, visit the University of Florida IPM website.

Not All Roundup® is Glyphosate

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