Red rice competition and control in cultivated rice
Studies were conducted to evaluate rice competitiveness with red rice and how to utilize glufosinate- and imazethapyr-resistant rice in water-seeded rice to control red rice. In the interference study, CL 121, Cocodrie, Drew, and Jasmine were seeded to obtain 95, 190, and 290 plants/sq m. Red rice density was 0 or 20 red rice plants/sq m. Jasmine, a tall, vigorous tillering, mid-season cultivar was more competitive with red rice. With the exception of Cocodrie grown red rice free, no benefit existed from increasing the seeding rate above 190 plants/sq m. Another study examined the effect of permanent flood establishment in a glufosinate- and imazethapyr-resistant rice system. Glufosinate controlled hemp sesbania, red rice, barnyardgrass, and Amazon sprangletop at least 95%. Imazethapyr controlled hemp sesbania less than 35%. With one exception, barnyardgrass, red rice, and Amazon sprangletop control was at least 95%. Two postemergence imazethapyr applications controlled Amazon sprangletop 79%. All treatments reduced red rice panicle number to less than 1/sq m, but did not delay red rice panicle emergence with respect to rice panicle emergence. Delaying the permanent flood improved rice yield in an imazethapyr system, but not for glufosinate. Another study examined the effect of 500 g/ha glufosinate applied 14, 28, 42, 56, and 70 days after emergence fb 410 g/ha applied 7 d later on rice and red rice. All treatments controlled red rice 91 to 98%. Rice yield was optimized when applications occurred within 35 or 49 DAE for the red rice infested and red rice free treatments, respectively. The fourth study examined imazethapyr use in a water-seeded system receiving no tillage or tilled in the water prior to seeding. Herbicide treatments were 70 g/ha imazethapyr applied 1, 3, or 5 d fb 70 g/ha applied 12 or 19 d after draining the seeding flood (DADSF), 140 g/ha applied 12 or 19 DADSF, and a nontreated. All treatments controlled red rice 88 to 95% and barnyardgrass 73 to 94%. Rice yields did not reflect barnyardgrass control and were higher when the two imazethapyr applications were farther apart.
Oryza sativa, competition, liberty-link, clearfield
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Plant, Environmental Management and Soil Sciences