Cool Wet Weather Impacting Herbicide Applications In Corn

 

With the cool weather interspersed with rain, some corn has yet to emerge or has emerged and appears pale and in desperate need of a shot of sunlight. If you have emerged corn and have not yet applied a soil residual herbicide, we would suggest waiting a few days until air temperatures are warmer and the corn has greened a bit to reduce the potential for herbicide injury.

 

For Roundup Ready corn, the potential for injury from glyphosate is minimal even with the cold stress. However, for many residual herbicide applications, a few days of warmer temperatures and sunlight will ensure better corn tolerance.

 

The following table provides the maximum corn size for delayed PRE or early POST herbicide application to corn. In summary Balance Flexx and Corvus contain a safener and can be applied early POST (V2 growth stage) to corn. Other herbicides such as Bicep II Magnum, Cinch ATZ, Dual II Magnum, etc. can be applied to corn up to 5 inches tall. Acetochlor-containing products such as Degree (Xtra), Harness (Xtra), Keystone, and SureStart or TripleFlex II can be applied to corn up to 11 inches tall. Herbicides including Atrazine, Acuron, Lumax, Lexar, and Resolve can be applied to corn up to 12 inches tall (20 inches tall for Resolve Q). Anthem/Anthem ATZ or Zidua can be applied to corn up to V4. And finally, Prowl H2O, Halex GT, and Warrant can be applied up to 30-inch tall corn. Keep in mind, when tank-mixing with other pesticides, to follow the most restrictive product label. Refer to the most recent herbicide label for use guidelines and additional information.

 

Table 1: Maximum corn size for delayed preemergence/early post herbicide application. for a more complete list of herbicides, see Table 2-10 in the new Mid-Atlantic Field Crop Weed Management Guide.