Too Many Reports Of Palmer Amaranth Escapes In Cotton And Soybean

DR. LARRY STECKEL AND SALLY REED

JACKSON, TENNESSEE

There have been too many reports of Palmer amaranth escaping multiple applications of dicamba, Liberty and/or dicamba tankmixed with Liberty.  Of course, we all have known for sometime that we have an ever-spreading biotype of dicamba-resistant Palmer amaranth in West Tennessee.  Liberty on the other hand has been much more consistent controlling pigweed.  Until it wasn’t.

Our field observations over the past couple weeks in Fayette, Gibson, Lauderdale and Haywood counties have been that even small 2 to 3” pigweed is occasionally escaping Liberty.  Even pushing the Liberty rate and applying it in the middle of the day has seen an alarming number of escapes in some of our research in Gibson and Lauderdale counties (Picture 1).   The ability of Liberty to prop up the pigweed control in the Liberty/dicamba tankmix has been greatly compromised in these fields (Picture 2).

Rescue treatments in cotton would be to get the cultivators and hoods back in functioning condition. A hooded application of Gramoxone + diuron or Caparol or Valor is a very effective option in cotton.  In wide-row soybean cultivation would be the best option.   ∆

DR. LARRY STECKEL AND SALLY REED

UNIVERSITY OF TENNESSEE