Palmer amaranth was known to be in west Kentucky, but now reports peg it in several counties bordering Tennessee and Ohio River in past few years. Last week, it was reported in Shelby County near Louisville. Palmer amaranth is a growing threat to Kentucky grain crop production.

Last year Palmer amaranth was found on a farm in Hardin County and two additional fields in Mercer and Garrard counties.

University of Kentucky Extension weed specialists JD Green and Jim Martin say it is not clear how the weed showed up on the farms. But in a June 9 blog, they have some ideas:

“It is known that the seed of Palmer amaranth can be introduced when cotton hulls are fed to livestock and the subsequent manure spread on crop fields. Other possible routes for introduction can be from transport of farm equipment and trucks hauling supplies from the southern regions of the US where Palmer amaranth is widespread.

After Palmer amaranth becomes established it can be difficult to control. Many populations of this plant are known to be resistant to glyphosate. Crop producers across Kentucky need to be on the lookout for this weed in both soybean and corn fields.

Young Palmer amaranth plants can look similar to other pigweed species. This species has smooth stems and longer leaf petioles than other types of pigweeds. If you notice a plant that has this general appearance you may need to confirm its identification. “

Catching the presence of this weed before large populations become established in crop fields can help minimize a larger economic impact in the future, they warn.

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