Confirmation and control of glyphosate-resistant common waterhemp (Amaranthus rudis) in Nebraska

Debalin Sarangi, Lowell D. Sandell, Stevan Z. Knezevic, Jatinder S. Aulakh, John L. Lindquist, Suat Irmak, Amit J. Jhala

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Glyphosate-resistant common waterhemp is a difficult-to-control annual broadleaf weed that has become a serious management challenge for growers in Nebraska and other states in the United States. The objectives of this study were to confirm glyphosate-resistant common waterhemp in Nebraska by quantifying level of resistance in a dose-response study, and to determine the sensitivity and efficacy of POST soybean herbicides for controlling suspected glyphosate-resistant common waterhemp biotypes. Seeds of suspected glyphosate-resistant common waterhemp biotypes were collected from seven eastern Nebraska counties. Greenhouse dose-response experiments were conducted to evaluate the response of common waterhemp biotypes to nine rates of glyphosate (0 to 16×). Common waterhemp biotypes were 3- to 39-fold resistant to glyphosate depending on the biotype being investigated and the susceptible biotype used for comparison. Results of the POST soybean herbicides efficacy experiment suggested that glyphosate-resistant biotypes, except a biotype from Pawnee County, had reduced sensitivity to acetolactate synthase (ALS)-inhibiting herbicides (chlorimuron-ethyl, imazamox, imazaquin, imazethapyr, and thifensulfuron-methyl). Glufosinate and protoporphyrinogen oxidase (PPO)-inhibiting herbicides (acifluorfen, fluthiacet-methyl, fomesafen, and lactofen) provided ≥ 80% control of glyphosate-resistant common waterhemp at 21 d after treatment (DAT). This study confirmed the first occurrence of glyphosate-resistant common waterhemp in Nebraska, and also revealed reduced sensitivity to ALS-inhibiting herbicides in most of the biotypes tested in this study. Nomenclature: Acifluorfen; chlorimuron-ethyl; fluthiacet-methyl; fomesafen; glufosinate; glyphosate; imazamox; imazaquin; imazethapyr; lactofen; thifensulfuron-methyl; common waterhemp, Amaranthus rudis Sauer; soybean, Glycine max (L.) Merr.

Original languageEnglish (US)
Pages (from-to)82-92
Number of pages11
JournalWeed Technology
Issue number1
StatePublished - Mar 1 2015
Externally publishedYes


  • Acetolactate synthase inhibitor
  • glutamine synthetase inhibitor
  • protoporphyrinogen oxidase inhibitor
  • resistance management


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