The crazy warm and mostly dry February has many folks thinking about planting March corn. If this is the case on your farm, it is time to be applying burndown. This is particularly true for fields infested with ryegrass. The reason for this is that clethodim tankmixed with glyphosate has been the “go to” for ryegrass control. The time concern is that the typical plant back for corn after a clethodim application is 30 days.
If corn is to be planted within 30 days, the options for ryegrass are slim. One of those options is with sequential applications of Gramoxone applied about 10 to 14 days apart. Another option is going with the supplemental label for Select Max of 6 ozs of product applied no closer than 6 days ahead of planting. Where ryegrass is small the 6 oz/A rate of Select Max mixed with a qt of glyphosate works fairly well. On the other hand, for more well established ryegrass the level of control using that low rate of Select Max will be sketchy. This can be greatly improved if Gramoxone tankmixed with Atrazine is applied 7 to 14 days after the glyphosate and Select Max tankmix.
In the case of all other winter annual weeds we can, fortunately, mix atrazine in with the burndown. Gramoxone Inteon or glyphosate tankmixed with atrazine or any of the more popular premixes (i.e. Acuron, Lexar, Corvus, Fultime NXT) can provide a very effective burndown of even large existing weeds.
If the field is likely to be planted to corn but may change to soybean or grain sorghum then Verdict or Sharpen can substitute for the atrazine. Of the two, I prefer Verdict as it can provide residual Palmer amaranth control from both the group 15 herbicide (Outlook) and the group 14 herbicide (Sharpen).