SMART CHOICES: HOW TO PICK
THE RIGHT HERBICIDE TO KILL WEEDS
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By Kai Umeda, a member of the Weed Science Society of America
Local garden centers and home improvement stores offer a dizzying array of herbicide choices for weed control. But how do you know which product is best for eliminating the weeds in your lawn, garden, flower bed, driveway or patio? To make the most effective and economical choice, you need to get “up close and personal” with the weeds growing around your home and answer a few important questions.
What weeds do you have?
It is vital that you select an herbicide that has the weeds you want to kill listed on its label. So examine those unwanted invaders growing around your home and find out what they are. Are your weeds annuals like crabgrass, foxtail and some spurges that live for just one season? Or do you have harder to control perennial weeds like nutsedge, dandelions or common plantain that recur each year from the same root system?
There are many photos and resources online to help. For example, the University of Arizona where I work has a database of weed photos. You can find similar resources hosted by educational institutions around the country, and the Weed Science Society of America hosts a photo gallery. If you can’t find what you need online, take a sample to your Cooperative Extension agent, or talk to an expert at your local garden center.
What is your goal – preventing weeds or eliminating those already growing?
A spring application of preemergence herbicides will generally prevent the weeds listed on the herbicide label from emerging. Preemergence herbicides can be especially helpful in keeping crabgrass out of your lawn. If you encounter annual weeds every year in the same location, a preemergence herbicide can be used as a barrier against anticipated problem weeds.
Postemergence herbicides target weeds already up and growing. When sprayed on foliage, they penetrate throughout the plant system and cause it to die. Some postemergence products are “nonselective,” which means they could harm desirable plants as well as weeds. They can be great for driveways, patios, walkways and fence lines where you want control of all vegetation. But you wouldn’t want to use a hose-end sprayer to broadcast a nonselective product across a vegetable garden, lawn or bed filled with prized flowers. Where weeds grow close to desirable plants, you might try to find a foam applicator or a very precise spray to target only unwanted weeds.
Are you looking for the convenience of an “all-in-one” or “weed and feed” product?
If the weeds you want to eliminate are in your lawn, you have a few additional options to consider. Certain “weed and feed” products combine fertilizer with preemergence herbicides so you can benefit from weed prevention while providing nutrients to your lawn. There are even “all-in-one” products that combine both preemergence and selective postemergence herbicides. You’ll be able to prevent weed seedlings from emerging and also kill existing weeds. Just proceed with care and make sure that the product is labeled for use on your specific turf species so you won’t ruin your lawn.
How much herbicide will you need?
If you’re treating a small area, you may want the convenience of a “ready-to-use” weed control product that does not have to be diluted with water. When treating many weeds across a broader area, though, you may want to consider a more economical concentrated product. In either case, buy only the amount of herbicide you need for the calculated area that you plan to treat. You’ll save money and avoid having to store herbicides safely around the house.
Making your selection
Once you’ve thought through these important questions, read the product labels and select an herbicide that works on the weeds growing around your home. Follow the instructions precisely and you’ll be on the path to successful weed control.
This column is provided as a courtesy by the Weed Science Society of America (WSSA). The author Kai Umeda is a Cooperative Extension Agent in the College of Agriculture and Life Sciences at the University of Arizona.
A FEW OF THE MANY WEBSITES THAT CAN HELP YOU IDENTIFY WEEDS:
- Connecticut Agricultural Experiment Station
- Iowa State University
- Michigan State University
- Mississippi State Extension
- National Gardening Association
- Ohio State University Extension
- Purdue University Extension
- Rutgers New Jersey Agricultural Experiment Station
- University of Arizona
- University of California Statewide Integrated Pest Management Program
- University of Florida Extension
- University of Georgia
- University of Illinois, Weed Science
- University of Kentucky
- University of Massachusetts Weed Herbarium
- USDA Plants Database
- Utah State University Extension
- Virginia Tech Weed Identification Guide
- Weed Science Society of America
University weed ID pages: https://old.wssa.net/weed/weed-identification/weed-id-pages/
Crabgrass, free image downloadable at:
http://www.ipmimages.org/browse/detail.cfm?imgnum=5402703
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Dandelion, free image downloadable at:
http://www.invasive.org/browse/detail.cfm?imgnum=5398431
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