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Waterhemp: A 'friendly' native evolves into the Cornbelt’s worst weed problem.

November 11, 2019 7:08 AM
Blog Post

Waterhemp’s rise to the Cornbelt’s worst weed is one of the Cornbelt’s more fascinating weed-related events over the past 40 years.  Waterhemp (Amaranthus tuberculatus) is native to the United States but is a relative newcomer to crop fields. Prior to waterhemp’s ascent, redroot pigweed (A. retroflexus) and smooth pigweed (A. hybridus) were the pigweed species most commonly found in crop fields. Pammel (1913) described redroot pigweed as abundant in every Iowa county, whereas he stated waterhemp (A.

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A good time to scout for Palmer amaranth

July 24, 2017 12:11 PM
Blog Post

As of February 2017, Palmer amaranth (Amaranthus palmeri) had been found in 49 of Iowa’s 99 counties.  A native of the American southwest, Palmer amaranth is more competitive than common waterhemp (Amaranthus tuberculatus), a pigweed native to Iowa.  These two species are two of the most troublesome for corn and soybean farmers.  Both species are known for fast development of herbicide resistance, incredible seed production on female plants (>500,000 seeds possible), and prolonged emergence.

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