Weed Control and Herbicides

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.

Tips for selecting and using herbicides:

• 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.

Weed Identification Resources

• Weed Identification - UC Extension
• Encycloweedia - California Department of Food and Agriculture
• Weed Photos - Weed Science Society of America
• Invasive and Noxious Weeds - USDA
• Plant Fact Sheets and Guides - USDA

Lawn Weed Control

• Guide to Healthy Lawns - UC Extension
• Weed Management in Lawns - UC IPM Fact Sheet
• Broadleaf Weed Control in Lawns - CSU Extension
• Control of Annual Grassy Weeds in Lawns - CSU Extension
• Guidelines for Herbicide Use - Weed Control Handbook
• Choosing a Herbicide - Extension Infonet
• Safety with Lawn Herbicides - Extension Infonet
• Healthy Lawn, Healthy Environment - EPA

Selecting Herbicides

• Herbicides - UC Extension
• Weed Control Methods Handbook - UC Extension
• Herbicide Behavior in Soil - CSU Extension
• How Herbicides Work - Univ. of Illinois
• Weed Susceptibility to Herbicides - UC Extension
• Choosing a Herbicide - Extension Infonet
• EPA Finds Organic Arsenical Herbicides Ineligible for Reregistration - EPA Press Release
• Herbicide Mode-Of-Action Summary - Purdue University Extension
• Aquatic Plant Management - Washington State Department of Ecology
• Toxicology and Active Ingredient Factsheets

Alternative Methods

• Non-Toxic Weed Control - Bio-Integral Resource Center
• Hand Weeding - UC Extension
• Corn Gluten - VA Soil and Water Conservation District
• Weed Control Handbook - UC Extension
• Managing Crabgrass without Herbicides - UMass Extension

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