Weed Control Guide for Ohio Field Crops

Total Postemergence Soybean Herbicide Programs

Total postemergence herbicide programs (one application) can be used in fields with:

• low to moderate populations of most annual weeds
• low to moderate populations of giant ragweed

Avoid use in fields with:

• moderate to high lambsquarters or grass populations
• high giant ragweed populations
• marestail
• late-season perennials such as hemp dogbane

Advantages:

• one-pass, can plant first and apply later (except for burndown in no-till soybeans)
• not dependent upon rainfall for postemergence activity (although soil moisture status affects weed response to herbicides)
• consistent control of low to moderate annual weed populations

Disadvantages:

• narrow window of application depending upon weather should be applied before weeds exceed about 6 inches in height to avoid yield loss
• a second POST application may be needed for late-emerging weeds that are not suppressed by the soybean leaf canopy
• application may be too early for best perennial weed control

Approaches:

Apply a herbicide treatment with activity on grass and broadleaf weeds before weeds exceed 3 to 6 inches in height (4 to 8 inches for Roundup Ready soybean program). Examples:

Glyphosate (Roundup Ready soybeans)
Synchrony STS + Select (STS soybeans)
Flexstar + Fusion
Raptor

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