INHERITANCE OF RESISTANCE TO DICLOFOP-METHYL AND FENOXAPROP-P-ETHYL IN 2 AVENA-SATIVA X AVENA-FATUA POPULATIONS

Since the late 1980s, several reports of herbicide-resistant wild oat have raised concern about potential weed control problems in western C anada. This study was conducted to determine the mode of inheritance, number of genes and type of gene action governing herbicide resistance in two Avena sativa x A. fatua crosses. The herbicide-susceptible A. sativa cultivars, Random and Derby, were crossed with a resistant A. f atua genotype, GP-HR-01. Parents, F(2)s and F-2:3 families were tested for their reactions to two post-emergent wild oat herbicides, diclofo pmethyl and fenoxaprop-p-ethyl, in the greenhouse. inheritance of resi stance to diclofop-methyl and fenoxaprop-p-ethyl was dominant and mono genic in the Derby/GP-HR-01 cross, but was controlled by two dominant complementary genes in the Random/GPHR-01 cross. Resistance to both he rbicides appeared to be controlled by the same genes or groups of tigh tly linked genes.