Confirmed resistance to aryloxyphenoxypropionate herbicides in Phalaris minor populations in Iran

Abstract

Phalaris minor (littleseed canary grass) is a major weed in wheat fields in some parts of Iran.<br><br>Diclofop-methyl, fenoxaprop-P-ethyl, and clodinafop-propargyl are three acetyl coenzyme A<br><br>carboxylase (ACCase)-inhibiting herbicides that are commonly used to control this grass in<br><br>wheat fields.Thirty-four P. minor populations with suspected resistance to ACCase-inhibiting<br><br>herbicides were sampled from wheat fields in the provinces of Fars and Golestan in Iran.The<br><br>dose–response assays that were conducted under controlled greenhouse conditions indicated<br><br>that 14 populations were resistant to fenoxaprop-P-ethyl, seven populations were resistant to<br><br>both fenoxaprop-P-ethyl and diclofop-methyl, and three populations were resistant to<br><br>fenoxaprop-P-ethyl, diclofop-methyl, and clodinafop-propargyl. These populations showed<br><br>different levels of resistance to the applied herbicides, compared to the susceptible population.<br><br>These results suggest that different mechanisms of resistance could be involved.The enzyme<br><br>assay revealed that the existence of modified ACCase in the three most-resistant populations<br><br>(AR, MR4, and SR3) is responsible for the resistance of these populations.