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Palmer Amaranth in North Dakota:?Why Should We Care?

Tuesday, August 27, 2019
filed under: Weeds

Though High Plains sunflower producers have dealt with it for a number of years, Palmer Amaranth has started grabbing headlines in the Dakotas as well of late, given its more-recent discovery in those two states.  Brian Jenks, weed scientist with North Dakota State University’s North Central Research Extension Center at Minot, addressed its threat in his NSA Summer Seminar presentation, “Palmer Amaranth: It’s now in North Dakota, But Why Should We Care?”
       There are plenty of reasons for caring, Jenks emphasized.  Chief among them:  Palmer Amaranth is a very prolific producer of seed; it germinates throughout the growing season; and it is very prone to herbicide resistance.
     The weed grows aggressively — up to two to three inches per day under optimum conditions — and can produce up to one million seeds per plant.  Yield reductions of as high as 91% have been reported in corn; up to 79% in soybeans.
       Palmer Amaranth can be introduced into an area in a variety of ways, Jenks related: via custom combines, used equipment coming in from other states, contaminated seed, bird feed or bird migration, water movement, in hay or livestock feed, and in manure.
       Current herbicide options in sunflower include:

Preplant or PRE — Roundup, Sonalan or Prowl, Spartan, Authority Supreme, Dual and Zidua
Postemergence — Express, Beyond

The key to managing Palmer Amaranth if it does show up on one’s farm, Jenks said, “is to not let anything go to seed; 99% control of Palmer is a failure.” That’s a goal that’s obviously much easier stated than achieved, but the NDSU weed scientist was adamant in recommending its ardent, proactive pursuit.

— Don Lilleboe