Friday, June 21, 2024

Manage large Palmer amaranth escapes

• By Larry Steckel and Delaney Foster •

large palmer amaranth escapes
Picture 1. Palmer amaranth escapes from Engenia + glyphosate. Picture taken 30 days after application — photos by Larry Steckel

We have visited fields where growers assumed their Engenia or XtendiMax + glyphosate had controlled Palmer amaranth only to find that many had escaped and are now quite large (Picture 1). The question is what are some approaches to manage these escapes?

In cotton, one option is to come back with another dicamba application. Of course, if Palmer amaranth was not controlled the first time it was sprayed with dicamba, another application on 3-foot tall pigweed has no chance.

Though this is true, it can roll them down some to where a hood can get over them more efficiently with a follow-up application of paraquat or glufosinate (Picture 2). Ideally a chopping crew follows to get the misses.

8 days after 2nd dicamba treatment
Picture 2. Large Palmer amaranth escapes eight days after second Engenia + glyphosate application.

In soybeans, the options are few. An application of Liberty would be the best option. Unfortunately, that may no longer be an option for many due to lack of supply.

The only other herbicide options would be Ultra Blazer or Cobra applied at maximum rates along with 1% MSO. This will likely cull some Palmer out but also leave a good many untouched. Then follow with a chopping crew to go after the many misses.

Dr. Larry Steckel is Extension weed specialist; Delaney Foster is a graduate research assistant. Both are with the University of Tennessee. 

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