Red rice (Oryza sativa) status after 5 years of imidazolinone-resistant rice technology in Arkansas

Certified Crop Advisors of Arkansas and members of the Arkansas Crop Consultants Association were surveyed in fall 2006 through direct mail to assess the current situation of the red rice problem and early impact of imidazolinone-resistant (IMR) rice technology on red rice infestation. The information generated represented 40% (226,800 ha) of rice production areas in Arkansas. Barnyardgrass and red rice were the most problematic weeds, with 62% of fields infested with red rice. The estimated economic loss due to red rice averaged $274/ha. Red rice infestation was prevented mostly by crop rotation (96%) and use of certified seed (86%). Of the red rice-infested fields, 38% had light infestation and 26% had severe red rice problems before adopting IMR rice. Thirty-seven percent of infested fields had been planted with IMR rice once and 43% at least twice. Approximately 85% of the consultants reported > 90% red rice control when using IMR rice. The majority (92%) of IMR rice growers rotate to other crops, mostly soybean. Unsuitable field condition was the main reason for growing only rice. After 3 seasons, the consultants perceived that red rice infestation level declined by 77% on average. The herbicide-resistance gene had escaped to red rice in some fields, and 90% of growers are exerting effort to mitigate outcrossing.