Weed Control and Herbicides

spot spraying problem weeds, photo credit: Lynn Betts, USDA Natural Resources Conservation Service

If you decide to use an herbicide to control weeds, be sure to select the appropriate product for your situation. There are hundreds of different herbicides on the market.

Control tips:

Be sure to read, understand and follow all of the label directions when mixing and applying herbicides.
Make sure the label clearly states that the product can be used in the manner you intend to use it.
Remember, more is not better. Use the application rate on the label.
Some herbicides are selective, and only kill certain types of plants, while others are non-selective and kill almost any type of plant.
Some herbicides kill weeds quickly, others can take up to a week or more.
Some herbicides persist in plants and soils for long periods of time, while others only remain in plants or soil for a short time.
Some herbicides have active ingredients that are more likely to move through soils towards groundwater. Others are much less likely to move through soils.

The following list of resources is intended to provide an overview of weed control and herbicides. If you have specific questions about herbicides, or about any of the information provided below, feel free to call NPIC.

If you just want some advice about how to control weeds, you may want to talk with staff at your local cooperative extension service. NPIC Specialists cannot give treatment recommendations, but extension agents often can. NPIC Specialists can answer your questions about an herbicide's potential health impacts, environmental effects, and/or chemical properties. Our mission is to provide objective, science-based information about herbicides in order to empower people to make their own informed decisions.

If you have questions about this, or any pesticide-related topic, please call NPIC at 1-800-858-7378 (8:00am - 12:00pm PST), or email us at npic@ace.orst.edu.

Additional Resources:

Weed Identification - Univeristy of California Statewide IPM Program
Broadleaf and Grass Weed Seedling Identification Keys - University of Minnesota Extension Service
Encycloweedia - California Department of Food and Agriculture
Weed Photos - Weed Science Society of America
Invasive and Noxious Weeds - US Department of Agriculture
Plant Fact Sheets and Guides - US Department of Agriculture
Weed Information - University of California, Davis
Creating a Weed Management Plan for Your Organic Farm - Penn State Extension
Weed Management on Organic Farms - NC State University Cooperative Extension
Paraquat Dichloride: One Sip Can Kill - US Environmental Protection Agency

Lawn Weed Control:

Guide to Healthy Lawns - Univeristy of California Statewide IPM Program
Weed Management in Lawns - Univeristy of California Statewide IPM Program
Control of Annual Grassy Weeds in Lawns - Colorado State University Extension
Guidelines for Herbicide Use - Weed Control Handbook - Global Invasive species Team
Keep Pets Safe Around Pesticides (p.5-Weeds) - Oregon State University Extension
Greenscaping: The Easier Way to a Greener, Healthier Yard - EPA
Moss and Algae Control In Lawns - Clemson University Cooperative Extension Service
Controlling Moss in Lawns - Oregon State University Extension Service
Weed Information - University of California, Davis
Lawn and Garden (Videos and Resources) - Environmental Protection Agency (EPA)

Selecting Herbicides:

Herbicides - Univeristy of California Statewide IPM Program
Weed Control Methods Handbook - Global Invasive Species Team
How Herbicides Work - University of Illinois
Weed Susceptibility to Herbicides - University of California, Riverside Extension
Choosing the Right Herbicide - University of Tennessee Extension
Herbicide Mode-Of-Action Summary - Purdue University Extension
Aquatic Plant Management - Washington State Department of Ecology
Control of Nuisance Algae in Ponds - West Virginia University

Alternative Methods:

Non-Toxic Weed Control - Bio-Integral Resource Center
Hand Weeding - Univeristy of California Statewide IPM Program
Corn Gluten - VA Soil and Water Conservation District
Weed Control Handbook - Global Invasive Species Team
Weeds and How to Deal with Them - Massachusetts Department of Agricultural Resources

Last updated November 14, 2016

Related Topics:

What are pests?

What are pesticides?