Henbit Control In Wheat

DR. LARRY STECKEL

JACKSON, TENN.
   Clearly henbit has had a very good start this fall.  Many fields are showing extensive infestations of this weed and a number of folks have called with questions on how to manage it in wheat. In some cases henbit has escaped a Gramoxone application and is now actively competing with the seedling wheat crop. In a few other cases the henbit has escaped tillage. Typically tillage or Gramoxone applied as a burndown before wheat will control henbit but the warm fall this year had helped henbit become well established by Mid-October which has resulted in sketchy control.
   So how do we go after the henbit now in wheat? Given the commodity price on wheat no one is wanting to break the bank on control measures so one option would be metribuzin. The rate most commonly applied is 2 to 4 oz/A of metribuzin. Though this herbicide can provide low cost henbit control some caution needs to be exercised when using metribuzin in wheat. I have seen 4 oz/A of metribuzin applied to fields that have eroded hill sides greatly injure wheat stands in Tennessee. This can also be the case for bottom fields that have a good deal of sand.    If the field is sandy or has a considerable amount of eroded hill sides then go with the lower 2 oz/a rate. If the henbit is well established and there is some doubt if 2 oz/A of metribuzin will work, then consider adding either 4 ozs/A of dicamba or a pint/A of 2,4-D.
When using metribuzin in wheat make sure the wheat has at least 3 to 4 tillers and has 4 secondary roots at least 2” long. Both dicamba and 2,4-D can be applied to wheat after it is well tillered but before jointing. ∆
   DR. LARRY STECKEL: Extension Weed Specialist, University of Tennessee