Under the cool and wet soil conditions that have persisted throughout most of Missouri this year, injury from preemergence residual herbicides is more likely to occur.

This is because corn plants are able to take up the herbicides at a rapid rate but are not able to metabolize or break down these herbicides at a similar pace. Some injury may also be attributable to the herbicide coming into direct contact with the seed as a result of wet soil conditions and/or failure to close the seed row.

Corn can exhibit a variety of injury symptoms at or soon after emergence as a result of preemergence herbicide applications. Herbicide injury to corn as a result of cool and wet soil conditions is perhaps most common with the soil-applied grass herbicides like metolachlor (Dual II Magnum/Cinch/Stalwart), acetochlor (Degree, Harness, TopNotch), alachlor (Lasso, MicroTech), dimethanamid (Frontier, Outlook), and flufenacet (Define), and also with any of the various atrazine pre-mixes that contain these herbicides (Bicep II Magnum, Lumax, Lexar, Cinch ATZ, Stalwart Xtra, Degree Xtra, Harness Xtra, FulTime, Keystone, Bullet, Guardsman, or Guardsman Max). In rare cases, corn seedlings may fail to emerge from the soil and “leaf out” underground as a result of injury from these herbicides.

“For more, click here>>”:http://ppp.missouri.edu/newsletters/ipcm/archives/v19n8/a2.pdf