Crabgrass,Digitaria spp., is a common lawn and garden weed in many states.

Weed Identification

Do you recognize the weed in this exhibit? It is Creeping Charlie, Glechoma hederacea. (Photo credit:Karen Jeannette)

Weed ID Keys

Identification of weeds through keys requires some knowledge about the plant characteristics of several different types of plants: broadleaf, grasses, and sedges. The following weed keys explain how to identify these differences and others to narrow down the field of possibilities.

• NCSU TurfFiles Weed and Turf ID (Center for Turfgrass Environmental Research and Education, North Carolina State University) is a helpful tool for identification of both weeds and types of cultivated grasses.

-User hint: Roll over the major headings: Broadleaf Weeds, Grasses, and Sedges to see a general description of each. Click on the type that best matches your weed (or grass) to see possible choices. You can click on check boxes for additional criteria to narrow down the selection or just click on the links to the right to view a description of that plant.

• The UC Guide to Healthy Lawns: Weed Key (Statewide IPM Program, University of California) is another helpful weed identification tool.

• Is this plant a weed? (University of Minnesota Extension). Identify weeds by clicking on pictures that best match the weed in question. Results of these weed searches yield more information on identification characteristics, plant significance, and control measures.

Weed Image Resources

• Weed Photo Gallery (University of California Statewide IPM Program).
• Invasive and Exotic Weed Search (Invasive.org).

Control

Garden

Hoeing is a good mechanical method of control for smaller weeds, especially those in confined spaces. (Photo credit: David Zlezak, University of Minnesota Extension)

• Cultural and Mechanical Weed Control in Vegetable Gardens (University of Rhodes Island Horticulture Program) discusses cultural and mechanical practices (nonchemical) of weed control.

• Weed Control in the Home Garden (Iowa State University) discusses nonchemical and chemical control practices.

• Cultural and Chemical Control of Weeds in Home Vegetable Gardens PDF (University of Maryland Extension) discusses nonchemical and preemergent chemical control practices.

Lawn

Dandelions replaced a lawn that failed to grow under poor growing conditions. (Photo credit: Karen Jeannette)

• Weeds and Your Lawn (University of Connecticut).
• Weed Control in Turf (University of Illinois Extension).
• Broadleaf Weed Control in Lawns (Colorado State University).
• Weed Management in Lawns (University of California Statewide IPM Program).
• Lawn Weed Resources (University of Florida Extension).

Landscape Plants

Tree seedlings and weedy grasses should be thoroughly removed from this area before landscape plants are planted. (Photo credit: David Zlezak, University of Minnesota Extension).

Ornamental landscape plants, such as trees, shrubs, and flowers look and do best when competition from weeds is kept to a minimum. Find management strategies for dealing with weeds in the landscape both before and after planting in the following Web site:

• Weed Management in Landscapes (Statewide Integrated Pest Management Program, University of California).

Herbicide Use and Products

Applying an herbicide. (Photo credit: Steve Dewey, Utah State University, Bugwood.org)

An herbicide is a pesticide specifically meant for controlling weeds. Herbicides and their use vary by state. The pesticide label is a legal document that provides instructions for proper pesticide usage. Another important document, the material safety data sheet (MSDS), informs the user about the chemical's physical properties and safe work practices. Labels are found on the pesticide container, but label and MSDS information can also be found by using the following Web sites. Some of these sites may require you to register free of charge before using.

Herbicide Chemical Information

• Home Use Pesticide Database (Colorado State Extension).

• Pesticide Information (Center for Urban Ecology and Sustainability, University of Minnesota).

• CDMS Agro-chemical Database (Crop Data Management Systems Inc.).

• Greenbook.net (Greenbook, Vance Publishing Corporation). (Has a search feature for locating labels and material data safety sheets for insecticides.)

Find state regulatory data for your state:

• KRSNetwork (Kelly Registration Systems Inc.)

-User hint: Under the "Our Services" tab, scroll down to find the Information Resources, then State Regulatory Data section, and select a state from the drop-down menu.