Revised June 2007

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Contents

• Principles of weed identification
• Weed scouting and mapping procedures
• Economic thresholds for weeds
• Herbicide injury
• Factors contributing to herbicide injury

Weed identification

Herbicides

• Herbicide mode of action families
• Growth regulators
• Amino acid synthesis inhibitors
• Lipid synthesis inhibitors
• Seedling growth inhibitors
• Photosynthesis inhibitors
• Cell membrane disruptors
• Pigment inhibitors

Related pages

• G1886, Controlling Drift of Crop Protection Materials
• IPM1021, Vine Weeds of Missouri
• IPM1023, Missouri Weed Seeds

Other related Web sites

• MU Extension Plant Diagnostic Clinic
• WeedSOFT™ yield loss calculator

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Practical Weed Science for the Field Scout: Corn and Soybean

Summer annual broadleaf

Copperleaf, Virginia (Acalyphya virginica)

A summer annual with leaves that have a distinctive copper coloration. Seedlings have round, smooth cotyledons. Virginia copperleaf is a weed of cultivated agronomic, nursery, and horticultural crops, landscapes and roadsides. First true leaves are opposite, while all subsequent leaves are alternate. Leaves are lanceolate in outline, 3/4 to 3 inches long, and occur on petioles. Youngest leaves develop a distinct copper coloration. Many inconspicuous green flowers occur in clusters in the areas between the stem and leaf petioles.

IPM1007, revised June 2007