Reports of Palmer amaranth escaping dicamba and/or glufosinate have been common the last couple of days.  Based on our recent research this is not a surprise as we have field and greenhouse studies showing that some Tennessee populations cannot be controlled with either herbicide (Figure 1).

In these populations even tankmixes of the two herbicides only increased Palmer amaranth control up to 50% or less. However, sequential applications of the dicamba + glufosinate tankmix applied about 14 days apart has increased control to about 70%.  This, of course, is still lacking but with these populations is about as good as one can expect.  In cotton, coming back with a hooded application of paraquat can readily take out those escapes.  In soybean, hopefully a good soybean stand can help suppress the pigweed regrowth.

In the future in these fields priority must be on keeping the Palmer amaranth from emerging as only partial control can be achieved with POST applications.

Figure 1.