By Larry Steckel
Just by driving through Tennessee there is no doubt we are a corn state this year. It seems like everywhere you look there is a field of corn. Much of this corn will get the "layby" application applied over the next 10 days. With the warm temperatures this early, the corn will quickly grow past the stage that herbicides like atrazine can be applied.
How large a pigweed will the popular layby premixes Halex GT, Capreno or Realm Q control? All three of those herbicides are a bleaching based herbicide premix. The bleaching herbicide in Capreno is Laudis. The bleaching herbicide in Halex GT and Realm Q is Callisto. Those herbicides can effectively control Palmer up to 6 inches tall depending upon rate. When Palmer becomes larger than that, a tank-mix partner is needed for consistent control.
The most commonly used tank-mix partner is atrazine. When atrazine is tank mixed in with one of those herbicide premixes mentioned above considerably larger Palmer can be controlled. However, atrazine can only be used on corn up to 12 inches tall.
What about large Palmer in corn that is taller than 12 inches?
One good option in tall corn is Liberty tankmixed with Capreno in Liberty Link corn. Liberty at 22 ozs/A can be tankmixed in with Capreno on corn up to 24 inches tall. In our research we have seen Palmer as large as 12 inches controlled with a tankmixture of Liberty + Capreno. The Callisto-based premixes cannot be tankmixed safely with anything other than atrazine on large Palmer. A sequential application of Status applied 7 to 10 days after the Callisto-based premix should finish off any large Palmer that escape the Callisto. Status may be applied at rates as high as 5 to 10 oz/A on corn from 4 inches to 36 inches tall.
There are some other options that do not include the premixes mentioned above that should be effective on large Palmer in tall corn. Callisto at 3 oz/a or Laudis at 2 to 3 oz/A plus Liberty at 22 oz/A would be an effective option on Palmer over 10 inches tall. Another effective option on large Palmer would be a tankmix of Status and Liberty. All of these combinations can be applied to corn up to 24 inches tall.
(Larry Steckel is an Extension weed specialist with the University of Tennessee.)