Glyphosate is one of the most widely relied upon herbicides worldwide and is the most commonly used herbicide within the United States. More commonly known in local hardware stores as Roundup®, glyphosate is a non-selective herbicide, meaning it will kill any type of grass or weed it comes in contact with. It is frequently used to kill off old grass before installing new sod as well as for tough, perennial weeds that return every year. Sod U explores glyphosate in more detail and discusses the best way to use this popular herbicide.
Glyphosate was first released in 1974 by the Monsanto Company (acquired by Bayer in 2018) with their product Roundup. As the patent held by the company expired in 2000, numerous other groups started using glyphosate as an active ingredient causing it to now be found in over 750 products sold in the United States. Glyphosate is now the most common herbicide used in home lawns, gardens and landscapes.
This active ingredient offers broad-spectrum control, meaning that it is able to target a large variety of weeds including grassy weeds, broadleaf weeds, shrubs, trees and both annuals and perennials; however, for larger plants like trees and shrubs, more than one application may be necessary. Because of this control, it can be used in multiple settings including landscapes, golf courses, home lawns and by farmers. For increased effectiveness, glyphosate, as a systemic herbicide, must be applied to plants that are actively growing so that it can move throughout the plant to disrupt the enzymes that create some of the plant’s essential amino acids. If your grass is in dormancy during the winter, for example, your grass is not actively growing and glyphosate applications will not be as effective.
Symptoms of injury to the plant can be seen as quickly as two days after application in some instances; however, this can be delayed slightly for perennial plants or if the weather conditions are not optimal.
When making an application of a product that contains glyphosate, the temperature should be above 60 degrees Fahrenheit, the wind should be minimal, the chance of rain should be low and the plants that the applicator is intending to control should be actively growing. If it rains before an application dries, the plants will not die; however, this can also be an advantage if a desirable plant is accidentally sprayed, as it may be saved if it is rinsed with water immediately. To minimize drift and the potential for harming desirable plants, the nozzle can be adjusted to create a coarser droplet size. It is also important to not walk over an area while it is still wet as this can transfer the product to other plants and cause injury.
When using any chemical control, it is essential to read the label carefully to ensure that you are using the proper safety equipment and wearing the appropriate protective equipment. Be sure to follow the instructions carefully for use, clean up and storage so that the product is effective and there are no unintended consequences.
Glyphosate is commonly used to as a non-selective herbicide, but there are many other non-selective herbicide alternatives. Read Alternatives to Glyphosate for Weed Control for more information on this subject. As previously mentioned, glyphosate is a broad-spectrum herbicide meaning it can control a large variety of weeds including grassy weeds, broadleaf weeds, shrubs, trees and both annuals and perennials. To get a better idea about the difference between grassy weeds and broadleaf weeds, take a look at our Identifying Common Lawn Weeds article. Our Weed Control article offers a variety of methods to help keep weeds at minimum—both preventive and curative.
Lastly, be sure to take a look at our full list of herbicide products you can buy online here.