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

Perennial broadleaf

Violet, common blue (Viola sororia)

A perennial from short rhizomes with heart-shaped leaves and blue or purple flowers, most commonly 2 to 5 inches tall. Leaves arise from a basal crown and occur on long petioles. Leaves are also hairless and have rounded teeth along the margins. Common blue violet is increasing as a weed of no-till cropping systems and is also commonly found as a weed of pastures, turfgrass, and landscapes.

IPM1007, revised June 2007