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

Mallow, Venice (Malva neglecta)

A summer annual weed of agronomic and horticultural crops. Seedlings have cotyledons that are round and occur on long, hairy petioles. First true leaves are alternate and irregularly shaped with toothed margins. All subsequent leaves are lobed at least three times and are arranged alternately along te stem. Flower stalks arise from the leaf axils and consist of five petals that are pale yellow to white in color with a purple base. The five sepals resemble a membranous bladder with distinctive dark green veins.

IPM1007, revised June 2007