Identification ofAvena fatuapopulations resistant to imazamethabenz, flamprop, and fenoxaprop-P

Abstract

Abstract Three Avena fatua (wild oat) populations resistant to imazamethabenz, flamprop, and fenoxaprop-P were identified from the northwest agricultural region of Manitoba, Canada. These populations were identified after producer reports of failure of imazamethabenz to provide satisfactory control in the field. Although these A. fatua populations had previously been exposed to other herbicides, primarily ACCase inhibitors, imazamethabenz had never before been applied. In growth room experiments, resistant (R) plants were 7.2 and 8.7 times more resistant to imazamethabenz and flamprop, respectively, than susceptible (S) plants, as measured by the ratio of dosages required to inhibit shoot dry matter accumulation by 50% (GR50 R/S). The three populations did not differ significantly (P < 0.05) in levels of resistance to imazamethabenz. Similarly, the populations did not differ in levels of resistance to flamprop. The populations differed in their response to fenoxaprop-P; levels of resistance for two popula...