Glyphosate, is the active ingredient in Roundup® and other herbicide (weed killer) products. It is systemic (absorbed by foliage and moves throughout the plant) and non-selective (can stunt and kill any plant). But, it has been in the spotlight as a possible cancer-causing compound. This has raised concerns among gardeners and land managers who use these products. How do you make the decision on whether or not to use these products in your own landscape?
1. Learn more about the toxicity and relative risks of glyphosate
Glyphosate Questions & Answers (2018)
Blog post from Oregon State University Extension
Herbicide Information Factsheet on Glyphosate (2016; updated Jan. 2019)
Dr. Joe Neal, North Carolina State University
Glyphosate Technical Fact Sheet (2010; revised March 2019)
National Pesticide Information Center, Oregon State University
2. Learn about herbicide alternatives to glyphosate
Are There Alternatives to Glyphosate for Weed Control in Landscapes? (2018)
by Dr. Joe Neal, NC State University
Vinegar: An Alternative to Glyphosate?
by Deborah Smith-Fiola, Independent IPM Consultant and Stanton Gill, IPM Specialist, University of Maryland Extension
Tips for reducing herbicide use
- First, identify the weed! Learn about its life cycle and habits. Is it an annual (lives for one growing season), biennial (two-year life cycle), or perennial (lives from year to year)? How does it reproduce and spread-- seeds, rhizomes (underground stems), etc.? What conditions favor its growth and spread? This information will help you manage the weed problem. These are the first steps of an Integrated Pest Management (IPM) approach see How to ID, Prevent, and Manage Plant Problems. Submit photos of your plants to Ask Extension or bring samples to your local Master Gardener plant clinic if you need help with identification.
- Learn to tolerate and accept non-aggressive weeds as a part of your lawn or landscape. Example: violets (are aggressive, but native), white clover, and dandelions growing in turf areas. Accept plant diversity in a lawn. Nimblewill is called a weed but it is actually a native grass.
- Minimize soil disturbance. Digging and cultivating brings weed seeds to the surface where they will germinate when exposed to light.
- Don’t let weeds flower and go to seed. At a minimum, cut them back or use a string trimmer.
- Mow high and fertilize properly to maintain dense turf.
- Use non-chemical methods
- Pull weeds when the soil is moist. This will make the job easier!
- Cover bare soil with mulch or groundcovers. Bare soil is an invitation for weeds to move in.
- Use an organic mulch (straw, tree leaves, shredded bark, grass clippings) to prevent weed growth in plant beds and around shrubs and trees.
- Cut weeds off at ground level with a sharp hoe or weeding tool (minimal soil disturbance).
- Smother weeds with weed barrier material (landscape fabric).
- Flame weeders burn weeds growing in pavement cracks.
Consider herbicide use when managing plants that are not effectively controlled using the above methods, are invasive (kudzu, Oriental bittersweet, etc.), or pose a human health risk (poison ivy).
If you decide to use an herbicide...
- Select a product labeled to control the targeted weeds (See tips on how to read a pesticide label).
- Read and follow the label, including the use of personal protective equipment (PPE).
Jon Traunfeld, Extension Specialist, University of Maryland Extension. Home and Garden Information Center Director
Christa Carignan, Coordinator, Digital Horticulture Education, HGIC
Debra Ricigliano, Lead Horticulturist, HGIC