Field trials were conducted in Georgia in 2007 to 2008 to evaluate the tolerance of three imidazolinone-resistant sunflower cultivars to POST applications of imazapic. There was no interaction between sunflower cultivar and herbicide treatment. When averaged over sunflower cultivars, imazapic, at 70 and 140 g ai/ha and applied at 30 d after planting, had no effect on sunflower above-ground biomass, plant height, seed-heads per meter row, and seed-head weights. Sunflower response to imazapic was similar to that of imazamox. Imazapic could be used in imidazolinone-resistant sunflower production systems without risk of unacceptable crop injury.

Nomenclature: Imazamox; imazapic; sunflower, Helianthus annuus L. ‘Dekalb 3880CL’, ‘Mycogen 8H419CL’, and ‘Mycogen 8N386CL’