Source: Penn State University
Table 2.2-10 (from The Penn State Agronomy Guide) Maximum corn size, weed sizes for delayed preemergence/early postemergence herbicide applications.
See specific herbicide label(s) for additional information on application. This type of application generally is used when weather conditions preclude the use of a standard preemergence program. For most products, do not apply in liquid fertilizer if com has emerged. Poor control from residual herbicides may result if annual grasses such as foxtail and panicum have emerged at the time of application; tank-mix with product that controls emerged grasses. Delayed preemergence/early postemergence programs can work well with herbicide-resistant corn hybrids now available (e.g., Roundup Ready and Libertylink). When tank-mixing with other pesticides, follow the most restrictive product label.
Maximum Corn and Weed Sizes
| Trade Name | Maximum Corn Size | Maximum Weed Size |
|---|---|---|
| Acuron | 12 inches | 3-inch broadleaves; inconsistent on emerged grasses |
| Acuron Flexi | 30 inches | 3-inch broadleaves |
| Anthem Maxx, Anthem ATZ | 4 collars (V4) | 2-inch broadleaves, before grass emergence |
| Atrazine | 12 inches | 1.5 inches |
| Axiom | before emergence | before emergence |
| Balance Flexx | 2-leaf (V2) | 1 true leaf stage |
| Bicep II Magnum | 4-leaf or 2 collars | 1- to 2-leaf |
| Corvus | 2-leaf (V2) | <2 inches (in general) |
| Dual | 5 inches | 2-leaf |
| Dual II Magnum, Bicep II Magnum, Bicep Lite II Magnum, Cinch ATZ Lite | 5 inches | 2-leaf |
| Fierce | before emergence | 2-inch broadleaves; by tank-mix partner for grasses |
| Guardsman Max/G-Max Lite | 12 inches | 1.5 inches broadleaves; before grass emergence |
| Halex GT | 30 inches | 4 inches |
| Harness, Harness MAX, Harness Xtra1, or Degree Xtra | 11 inches or by tank-mix partner | before broadleaf emergence, 2-leaf grasses or by tank-mix partner |
| Instigate | 2-leaf (V2) | 3 inches |
| Lexar EZ | 12 inches | 3-inch broadleaves; before grass emergence |
| Lumax EZ | 12 inches | 3-inch broadleaves; inconsistent on emerged grasses |
| Outlook | 12 inches | before emergence or by tank-mix partner |
| Prequel | before emergence | before emergence |
| Princep | before emergence | before emergence |
| Prowl H2O | 30 inches | before weed emergence |
| Python WDG/Accolade | 20 inches (V6) | before weed emergence |
| Resicore | 11 inches | 3-inch broadleaves |
| Resolve | 12 inches | 2-inch grasses; 3-inch broadleaves (in general) |
| SureStart II/TripleFLEX II11 inches | 11 inches | limited activity on 1-inch broadleaves; before grass emergence |
| Surpass NXT, FulTime NXT, TopNotch, or Keystone NXT, Breakfree NXT ATZ2 | 11 inches or by tank-mix partner | before emergence or by tank-mix partner |
| Verdict | before emergence | before emergence |
| Zemax | 30 inches (8-leaf) | 3-inch broadleaves; before grass emergence |
| Zidua | early postemergence | before emergence or by tank-mix partner |
1May be tank-mixed with Accent, atrazine (Harness), Banvel or Clarity, Marksman, Permit, or Roundup (Roundup Ready corn).
2May be tank-mixed with a number of different products, including Accent Q, Banvel or Clarity, Prowl, etc. See an herbicide label for specific information.