1 July 2003 Imazethapyr Application Methods and Sequences for Imidazolinone-Tolerant Rice (Oryza sativa)
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Experiments were conducted at two locations in Texas during 2000 and 2001 to compare barnyardgrass, broadleaf signalgrass, and red rice control; rice tolerance; and grain yield after single and sequential applications of imazethapyr in imidazolinone-tolerant rice. Red rice and barnyardgrass control on a clay soil at Beaumont was at least 94% with imazethapyr at 70, 90, and 100 g ai/ha applied preplant incorporated (PPI) or preemergence (PRE) followed by (fb) at least 40 g/ha of imazethapyr applied early postemergence (EPOST). Broadleaf signalgrass control on a very fine sandy loam soil at Eagle Lake was at least 86% when imazethapyr was applied PPI or PRE fb EPOST applications of imazethapyr. Sequential postemergence applications at Beaumont resulted in at least 95% red rice and barnyardgrass control when 40 g/ha applied late postemergence followed any EPOST application. Sequential postemergence applications at Eagle Lake controlled broadleaf signalgrass 98% during both years. Imazethapyr applied postemergence injured rice 0 to 34% up to 12 d after treatment. Rice yield reductions were correlated to weed control and most likely were not associated with early-season rice injury.

Nomenclature: Imazethapyr; imidazolinone; barnyardgrass, Echinochloa crus-galli (L.) Beauv. #3 ECHCG; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash # BRAPP; red rice, Oryza sativa L. # ORYSA; rice, Oryza sativa L. # ORYSA.

Additional index words: CLEARFIELD* rice, Newpath.

Abbreviations: EPOST, early postemergence; fb, followed by; LPOST, late postemergence; PD, panicle differentiation; PPI, preplant incorporated; PRE, preemergence.

BRIAN V. OTTIS, JAMES M. CHANDLER, and GARRY N. MCCAULEY "Imazethapyr Application Methods and Sequences for Imidazolinone-Tolerant Rice (Oryza sativa)," Weed Technology 17(3), 526-533, (1 July 2003). https://doi.org/10.1614/WT02-104
Published: 1 July 2003
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