Clearly the most frequent call the last few days of April and the first half of May has concerned corn replant. All through early May the calls have been on how to destroy a partial stand of corn and replant back to corn. In just the last few days the question has been on how to remove a poor stand of corn and then plant back to soybeans or cotton.
If soybean or cotton is to be planted back after a failed corn stand then the best option to remove the old corn is clethodim. The question then goes what rate of clethodim to use? Due to the fact that there are 1 pound, 2 pound and 3 pound clethodim products readily used, there can be some confusion on the rate.
Typically when discussing clethodim, I refer to Select Max which is a 1 pound product. If the corn is 2 leaf or less, then 6 to 8 ozs/A will typically provide good control. Some corn is up to 4 leaf in some fields so the rate should increase to 10 to 12 ozs/A for consistent control. Remember if the clethodim product to be applied is a 2 or 3 pound product the ozs/A should be reduced accordingly.
The next question then needs to be what and how much surfactant to add. Again it depends on the clethodim product used. The reason Select Max changed from a 2 pound active product to a 1 pound is because they added a lot of surfactant. As a result not much extra surfactant is needed over what is already in the jug. A quart of NIS/hundred gallons is all that is required if Select Max is being used.
If the clethodim product used is one of the 2 or 3 pound generics then more surfactant is required to get good corn control. Typically the recommendation with these products is 1 gallon of COC/hundred gallons of water.