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Abstract

The effect of light intensity, nitrogen (N), and water management on rice (Oryza sativa cv. 'Newbonnet' and 'Lemont') tolerance to fenoxaprop {(+)-2-[4[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid} was determined in two field studies at the Rice Research and Extension Center, Stuttgart, AR, in 1988 and 1989. In one study, 'Newbonnet' rice was treated with 0.22 kgai ha-1fenoxaprop at 0, 1, 3, 5, 7, 10, 14, and 28 days after N application and flooding. Moderate to severe foliar chlorosis, stunting, and stand and yield reductions occurred when fenoxaprop was applied within 7 days after N application and flooding. None to slight injury or yield reduction occurred when fenoxaprop was treated later than 7 days after N application and flooding. In the second study, 'Lemont 1 rice grown in full or reduced (53%) sunlight and treated with preplant incorporated or preflood N was sprayed with 0.17 kg ai ha-1 fenoxaprop 1 week before or after flooding. Injury at early to midseason was greater in plants grown in reduced sunlight than in full sunlight. Also injury was greater when fenoxaprop was applied after flood than when applied before flood. Although rice generally recovered from injury, its tolerance to fenoxaprop was reduced by N application and flooding particularly in reduced sunlight.

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