Palmer Amaranth Found in Adair County

Palmer Amaranth is a troublesome weed that has been in western Kentucky for several years and as of last week, its presence has been confirmed in both Adair and Taylor County. Palmer Amaranth is resistant to glyphosate and can pose major problems in soybean fields.   A warm season annual, individual Palmer Amaranth plants can produce up to a half a million new seeds when not faced with competition.  Palmer Amaranth can grow up to 2-3 inches per day reaching a height of 6 feet or more.  Higher populations of this weed has been found to reduce yield in soybeans by as high as 79%.

Palmer Amaranth can be difficult to identify as it’s characteristic are similar to other pigweed species.  Some key features of Palmer Amaranth that can be used to tell it apart from other pigweed species include:

·         Leaf petioles are longer than the leaf blade.

·         No presence of small hairs on the stem.

·         A small hair is present on the tip of the leaves.

·         Leaves are egg shaped (wide middle, smaller at base, and very narrow at the end)

·         Leaves may or may not have a white-V shape marking

Given its known presence, Adair County grain farmers should be scouting crop fields closely and apply herbicide treatments in a very timely manner.  Palmer Amaranth can be best controlled at a height of 3 inches or less.  Cobra and Flexstar are the best herbicide options available for post-emergence control of Palmer Amaranth.  If Palmar Amaranth is found prior to soybeans reaching full canopy, the herbicide Prefix is the preferred herbicide as it includes soil-residual control.  Growers who find Palmer Amaranth in their field should take swift measures to control this weed as it will quickly spread and will become even more difficult to manage.

If you find plants that you suspect are Palmar Amaranth, contact the Adair County Cooperative Extension Service at (270) 384-2317 or email multiple pictures of the plant to nick.roy@uky.edu. 

Always carefully read and follow label directions when using pesticides.  Mentions of trade names are for educational purposes only.  Generic formulations containing equivalent active ingredients may be available.

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