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

Spurry, corn (Spergula arvensis)

A summer annual with finely divided leaves that ranges from 6 to 18 inches in height. Leaves are bright green and threadlike, generally only 1/2 to 1 inch in length, occurring in whorls around the stem joints. Stems are hairy and sticky to the touch, much-branched. Flowers occur in terminal clusters at the ends of stems and are small with five white petals. Egg-shaped seedpods split open into five parts to release many black, flat, round seeds.

IPM1007, revised June 2007