Department of Agronomy, CCS Haryana Agricultural University, Hisar-125 004, India.
1 Centre for Weed Research, University Ghent, Coupure Links 653, B-9000 Ghent, Belgium.
Three black-grass (Alopecurus myosuroides Huds.) populations with resistance to chlorotoluron, fenoxaprop (through enhanced metabolism) and clodinafop (‘Zevekote 1997’, ‘Zevekote 1999-Control’ and ‘Zevekote 1999-Propoxycarbazone-sodium’) originating from the same field at Zevekote (province West-Flanders, Belgium), together with population ‘Peldon’ (chlorotoluron resistant standard from Peldon, U. K.) and ‘Rothamsted’ (herbicide sensitive standard from Rothamsted Experimental Station, U. K.), were subjected to soil-applied flupyrsulfuron-methyl (sulfonylurea) and propoxycarbazone-sodium (sulfonylaminocarboxyltriazolinone) in greenhouse bioassay experiments (small pot test method) with pre-plant incorporation into a sandy loam soil. With both herbicides, differential responses at the shoot fresh weight level were recorded among populations. Against f1upyrsulfuron-methyl and propoxycarbazone-sodium, both ALS inhibitor herbicides, the chlorotoluron resistant ‘Peldon’ and the three herbicide resistant populations from Zevekote (‘Zevekote 1997’, ‘Zevekote 1999-Control’ and ‘Zevekote 1999-Propoxycarbazone-sodium’) were found to be cross-resistant. These bioassay results with soil-applied flupyrsulfuron-methyl and propoxycarbazone-sodium correspond well with those obtained in field experiments with post-emergence applications of these herbicides.
