Resistance to PPO-inhibiting herbicide in Palmer amaranth from Arkansas

Reiofeli A. Salas, Nilda R. Burgos, Patrick J. Tranel, Shilpa Singh, Les Glasgow, Robert C. Scott, Robert L. Nichols

Research output: Contribution to journalArticlepeer-review


BACKGROUND: The widespread occurrence of ALS inhibitor- and glyphosate-resistant Amaranthus palmeri has led to increasing use of protoporphyrinogen oxidase (PPO)-inhibiting herbicides in cotton and soybean. Studies were conducted to confirm resistance to fomesafen (a PPO inhibitor), determine the resistance frequency, examine the resistance profile to other foliar-applied herbicides and investigate the resistance mechanism of resistant plants in a population collected in 2011 (AR11-LAW B) and its progenies from two cycles of fomesafen selection (C1 and C2). RESULTS: The frequency of fomesafen-resistant plants increased from 5% in the original AR11-LAW-B to 17% in the C2 population. The amounts of fomesafen that caused 50% growth reduction were 6-, 13- and 21-fold greater in AR11-LAW-B, C1 and C2 populations, respectively, than in the sensitive ecotype. The AR11-LAW-B population was sensitive to atrazine, dicamba, glufosinate, glyphosate and mesotrione but resistant to ALS-inhibiting herbicides pyrithiobac and trifloxysulfuron. Fomesafen survivors from C1 and C2 populations tested positive for the PPO glycine 210 deletion previously reported in waterhemp (Amaranthus tuberculatus). CONCLUSION: These studies confirmed that Palmer amaranth in Arkansas has evolved resistance to foliar-applied PPO-inhibiting herbicide.

Original languageEnglish (US)
Pages (from-to)864-869
Number of pages6
JournalPest Management Science
Issue number5
StatePublished - May 1 2016


  • ALS inhibitors
  • Amaranthus palmeri
  • Diphenyl ether resistance
  • Fomesafen
  • Multiple resistance
  • Resistance evolution

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Insect Science

Fingerprint Dive into the research topics of 'Resistance to PPO-inhibiting herbicide in Palmer amaranth from Arkansas'. Together they form a unique fingerprint.

Cite this