Five rice (Oryza sativa L.) cultivars were evaluated in the greenhouse for tolerance to fenoxaprop {(±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid}. Rice was more tolerant to fenoxaprop when flooded at 7 days after spraying, based on trends in reduction of weight of seedling topgrowth. ‘Lebonnet’ was the only cultivar that responded differently when five cultivars were compared. In the field, rice yield was not adversely affected by fenoxaprop applied at 168 g ai/ha and flooded 1 to 10 days after treatment, but yield increased as the time interval between application of 336 g ai/ha and flooding increased. Yield data suggested that flooding should be delayed at least 5 days when rice is treated with the high rate. The cultivar ‘Newbonnet’ was slightly less tolerant than 'Starbonnet’ in the field.
