Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
Fields with a history of Palmer amaranth (or in close proximity to fields with Palmer amaranth issues) should be scouted for postemergence applications. Postemergence control with the Group 27 herbicides, which include Callisto/Halex GT (mesotrione), Impact/Armezon, Laudis (or Capreno), in combination with atrazine are all very good. All of these products without atrazine are much less effective and often only stunt Palmer amaranth plants and do not kill them. Liberty (or other glufosinate products) is good provided there is good coverage (at least 15 gal/A and medium droplet size) and good sunlight. Dicamba as Diflexx/Diflexx Duo or Status will provide good control. Diflexx and Status both contain safeners for improved corn safety, but will not control large Palmer amaranth plants. So it’s important to scout the fields and treat early.