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| Giant ragweed. Photo credit: University of Wisconsin. |
Weed Identification
For chemical or cultural weed control to be effective, you need to know what weed species are present. Failure to identify the weed problem accurately may lead to wasted time and money, or excess pesticide applied to the environment.
Begin with seedlings. Weeds are most effectively controlled at a very young stage and it's important to identify them as early as possible. Unfortunately, many weeds look very similar at a young stage.
Throughout the season, scout for weeds and maintain these records on a "weed map". These maps are very useful in the spring if you are deciding on a preemergence herbicide to purchase, and they also help you to monitor the effectiveness of your weed control program.
There are many excellent resources available for identifying weeds. Here are a few to get you started:
NCR 607 Common Weed Seedlings of the North Central States
(4.4 MB pdf file). This guide is designed to help identify seedling weeds while there is still time to control them. This guide includes 54 of the most common weed species in the North Central region. Colored photographs are provided that highlight the distinguishing characteristics of the weed seedlings. Available online, or for purchase from the University of Wisconsin Learning Store.
Early Spring Weeds of No-till Crop Production
(3MB pdf file). Includes a key for identification and color photos. University of Illinois
Minnesota Weed Seedling Photo Collection
Weed Emergence Poster (1 MB pdf)
depicts the emergence sequence of 16 important weeds
Weed Identification
Online photo gallery at the University of Illinois.
University of Missouri Weed Identification Guide
Online photo gallery in which you can search for weeds by their scientific name or common name.
Online Weed Identification Tool
This online weed ID tool from the University of Wisconsin is organized to ask questions about the unknown plant and based on the user’s input, the program will produce a list of plants (scientific and common names) along with thumbnail images that match the information entered.