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1 September 2013 Weed Management Practices and Needs in Arkansas and Mississippi Rice
Jason K. Norsworthy, Jason Bond, Robert C. Scott
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Crop consultants in Arkansas and Mississippi were sent a direct-mail survey in fall of 2011 with questions concerning weed management in rice. The goal of the survey was to document the extent of imidazoline-resistant rice hectares, the herbicides most commonly recommended in rice, the weeds perceived to be most troublesome in rice including those resistant to herbicides, and suggested areas of research and educational focus that would improve weed management in rice. When appropriate, results from this survey were compared to a similar survey conducted in 2006. Completed rice surveys were returned by 43 consultants, accounting for 179,500 ha of scouted rice or 38% of the rice hectarage in Arkansas and Mississippi. Imidazolinone-resistant rice was grown on 64% of the hectares, and this technology was used continually for the past 5 yr on 11% of the rice hectares. Of the area planted to imidazolinone-resistant rice, 42% of this hectarage was treated solely with an acetolactate synthase (ALS)-inhibiting herbicide. Consultants listed improved control options for barnyardgrass and Palmer amaranth as the most important research and educational need in rice. The top five weeds in order of importance were (1) barnyardgrass, (2) sprangletops, (3) red rice, (4) northern jointvetch, and (5) Palmer amaranth. From a predetermined list of research and educational topics, consultants gave the highest ratings of importance to (1) control of herbicide-resistant weeds, (2) strategies to reduce the occurrence and spread of herbicide-resistant weeds, and (3) development of new economical herbicide-resistant rice varieties which was comparable to economical weed control options. Findings from this survey point to the overuse of imidazolinone-resistant rice and a lack of preemptive resistance management strategies such as crop rotation and use of multiple effective herbicide modes of action by some growers, which has likely contributed to selection for the ALS-resistant barnyardgrass and rice flatsedge recently confirmed in Arkansas and Mississippi rice.

Nomenclature: Barnyardgrass; Echinochloa crus-galli (L.) Beauv.; northern jointvetch; Aeschynomene virginica (L.) B.S.P.; Palmer amaranth; Amaranthus palmeri S. Wats.; red rice; Oryza sativa L.; rice; Oryza sativa L.; rice flatsedge; Cyperus iria L.; sprangletops; Leptochloa spp.

Se envió una encuesta vía correo electrónico a asesores agrícolas en Arkansas y Mississippi en el otoño de 2011 con preguntas relacionadas al manejo de malezas en arroz. El objetivo de la encuesta fue documentar la extensión de hectáreas de arroz resistente a herbicidas imidazolinone, los herbicidas más comúnmente recomendados en arroz, las malezas percibidas como las más problemáticas en arroz incluyendo aquellas resistentes a herbicidas, y las áreas sugeridas para hacer énfasis en investigación y educación que mejorarían el manejo de malezas en arroz. Cuando fue apropiado, los resultados de esta encuesta fueron comparados con una encuesta similar realizada en 2006. Las encuestas contestadas fueron devueltas por 43 asesores, contabilizando 179,500 ha de arroz evaluado o 38% del área de arroz en Arkansas y Mississippi. Arroz resistente a imidazolinone fue sembrado en 64% de las hectáreas, y esta tecnología fue usada continuamente durante los últimos 5 años en 11% de las hectáreas de arroz. Del área sembrada con arroz resistente a imidazolinone, 42% de esta área fue tratada solamente con un herbicida inhibidor de acetolactate synthase (ALS). Los asesores mencionaron mejores opciones de control de Echinochloa crus-galli y Amaranthus palmeri como las necesidades de investigación y de educación más importantes en arroz. L

Jason K. Norsworthy, Jason Bond, and Robert C. Scott "Weed Management Practices and Needs in Arkansas and Mississippi Rice," Weed Technology 27(3), 623-630, (1 September 2013).
Received: 26 November 2012; Accepted: 1 February 2013; Published: 1 September 2013

weed control
weed management survey
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