A study was conducted to test the effect of water clarity, as related to water seeding system, on herbicide efficacy in water-seeded imidazolinone-resistant rice production. Red rice control was 88 to 89% when 140 g/ha imazethapyr was applied in a single application immediately prior to permanent flood in the clear-water seeding system. All herbicide applications in either clear- and muddy-water systems controlled red rice 90 to 95%. The benefits of reducing soil erosion and surface water contamination from muddy-water discharge at seedling establishment can be obtained in a clear-water system without experiencing a decrease in weed control or rice yield.

Nomenclature: Imazethapyr, red rice, Oryza punctata Kotchy ex. Steud., rice, Oryza sativa L