As spring approaches, many homeowners in pursuit of a lush, weed-free lawn will turn to one of the many brands of “weed and feed” products that combine herbicides with fertilizer. But Cooperative Extension weed scientists say it is important to use these products responsibly in order to protect the environment.
“Combination ‘weed and feed’ products are popular because they are convenient and easy to use,” says Kai Umeda, area extension agent in turfgrass science at the University of Arizona and a member of the Weed Science Society of America (WSSA). “Each fertilizer granule in these combination products carries a bit of herbicide. The fertilizer provides nutrients for vigorous lawn growth, while the herbicide kills emerged weeds, prevents them from emerging or both.”
WSSA member Jeffrey Derr, an extension weed scientist with Virginia Tech, says one-step weeding and fertilizing also eliminates the mixing and potential drift associated with spray-on solutions. But even “weed and feed” products should be used with caution, he says. He recommends analyzing your weed problem carefully before you buy and exercising good stewardship during and after the application.
Here are nine tips recommended by Derr and Umeda:
- Decide your tolerance for weeds. If you don’t mind a few weeds in your lawn, you may not need an herbicide at all. Mow regularly at the correct height and maintain a dense, healthy stand of grass to keep weeds in check. Just make sure you don’t allow any weeds that remain to go to seed and spread. Also keep an eye out for perennial grassy or broadleaf weeds that can continue to flourish with mowing and will need to be controlled.
- Identify the culprits. Do you know what kind of weeds typically grow in your lawn? It is important information that can help you determine which “weed and feed” product to purchase. Crabgrass grows differently from dandelions, for example, so different herbicides are needed to control them. There are many resources you can turn to for help. One example: The Cooperative Extension Service can help you identify weeds and determine your control options. Visit https://www.usda.gov/topics/rural/cooperative-research-and-extension-services to find your local office and online resources.
- Identify your turfgrass. Cool-season turf species, such as tall fescue, Kentucky bluegrass and perennial ryegrass, should be fertilized primarily in the fall, not in the spring. Warm-season grasses like bermudagrass should be fertilized in late spring or early summer. If the right time to fertilize your lawn is not the right time to control your weeds, don’t apply a “weed and feed” product.
- Understand preemergence and postemergence herbicides. Crabgrass preventers must be applied before the weeds emerge. Most of the herbicides used for broadleaf weed control are applied after the weeds have emerged. These broadleaf products should generally be applied when there is dew on the weed foliage, allowing the granules to stick and release their herbicide.
- Read the label. Always do this first, even before you purchase the product. The label is the law, and you are legally obligated to read and follow everything that’s on it. The directions for use, precautions and other information are equally important.
- Measure and apply precisely. More is not better. To control your weeds, use the exact application rate specified on the label, at the recommended time of year or growth stage. Measure the area of the lawn to be treated and use a scale to measure the precise amount of product needed. You will waste money and may injure your lawn if you apply the wrong rate at the wrong time. Also avoid nearby ornamental landscape plants to protect them from potential damage.
- Sweep it up. Sweep or blow any “weed and feed” granules that fall on your driveway or sidewalk back onto the lawn. If you don’t, they can easily travel with rainfall into storm drains, ditches, creeks and other waterways. The same advice applies to any granular pesticide or fertilizer applied on lawns, around ornamentals or in gardens. Keep them precisely on target.
- Have a backup plan. Weeds already growing in your lawn won’t be controlled by a preemergence-type “weed and feed” product designed to keep weed seedlings from emerging. In addition, perennial weeds with creeping root systems, rhizomes or tubers pose a special challenge; you may need to spot spray them with a different herbicide at very specific times. Consult with your local Cooperative Extension specialist or visit extension websites for advice on how to best treat the types of weeds you have.
- Practice prevention. A thick, healthy lawn will out-compete weeds and can be less susceptible to disease and insect attack. Maintain optimum growth with proper use of fertilizers, regular mowing and timely irrigation. If your neighbor borrows your mower, clean it well before and after to keep from spreading weed seeds from lawn to lawn. Finally, take a close look at your lawn regularly so you can pull or hoe small weed outbreaks before they get out of hand.
“With ‘weed and feed’ products and other pesticides, good stewardship is really the responsibility of each individual,” Umeda says. “Take advantage of the excellent stewardship resources available from your local Cooperative Extension Service, your state’s Pesticide Safety Education Program coordinator (https://nifacontacts.ipmcenters.org/PSEPDirectory.cfm) and the national Pesticide Environmental Stewardship website (PES) at http://pesticidestewardship.org. The goal is to get the best weed control results you can, while always protecting the environment.”
About the Weed Science Society of America:
The Weed Science Society of America, a nonprofit professional society, was founded in 1956 to encourage and promote the development of knowledge concerning weeds and their impact on the environment. The Weed Science Society of America promotes research, education and extension outreach activities related to weeds, provides science-based information to the public and policy makers, and fosters awareness of weeds and their impacts on managed and natural ecosystems, and promotes cooperation among weed science organizations across the nation and around the world. For more information, visit http://www.wssa.net.