Herbicide resistant sunflower plants comprising two different herbicide-resistant alleles of the sunflower acetohydroxyacid synthase large subunit 1 (AHASL1) gene are described. Methods for making these sunflower plants and methods for controlling weeds or other undesired vegetation growing in the vicinity of these sunflower plants are disclosed. Such methods involve the use of acetohydroxyacid synthase-inhibiting herbicides. Methods for controlling parasitic weeds growing on sunflower plants are also described. Additionally provided are methods for determining the genotype of sunflower plants for AHASL1 gene.
