Resistance to PPO inhibiting herbicide in Palmer amaranth from Arkansas
Abstract 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. (c) 2016 The Authors. Pest Management Science published by John Wiley Sons Ltd on behalf of Society of Chemical Industry.
Pest management science