Weed Control Guide for Ohio Field Crops

Preemergence plus Postemergence Corn Herbicide Programs

Preemergence (PRE) plus Postemergence (POST) herbicide programs fit any field, but are especially well-suited for fields with:

• moderate to high annual grass populations
• moderate to high giant ragweed, cocklebur, velvetleaf, and annual morningglory populations
• perennial weeds
• burcucumber

Advantages of PRE plus POST programs:

• very consistent, as long as some rain on PRE
• creates wider window for POST application, compared to total POST programs
• good on many tough weeds

Disdvantages of PRE plus POST programs:

• dependence upon rain for PRE activity (although have planned POST backup)
• two-pass
• cost

Approaches:
In fields with low to moderate grass populations, can take an approach of preemergence grass herbicide followed by postemergence broadleaf herbicide (without much grass activity). Examples:

• Outlook followed by Clarity
• TopNotch followed by Hornet + Clarity

To provide postemergence control of a few grass escapes, can take an approach of a preemergence grass herbicide followed by a postemergence broadleaf herbicide that also has activity on small grasses. Examples:

• Dual II Magnum followed by NorthStar
• Outlook followed by Distinct
• Harness followed by Marksman

In fields with moderate to high grass and/or problem broadleaf populations, can take an approach of preemergence grass or grass+broadleaf herbicide (full or reduced rate) followed by broad-spectrum postemergence herbicide with grass and broadleaf activity. Examples:

• Leadoff followed by Basis Gold
• atrazine followed by Lightning + Distinct (Clearfield corn)
• atrazine + simazine followed by Liberty (Liberty Link corn)
• Harness Xtra followed by glyphosate (RR corn)
• Bicep followed by Spirit + Accent

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