Red Rice (Oryza sativa) Biology. II. Ecotype Sensitivity to Herbicides

Greenhouse studies were conducted to evaluate sensitivity of red rice ecotypes from Arkansas, Louisiana, Mississippi, and Texas to soil- and foliar-applied herbicides. Ecotype response to herbicides was variable. Molinate at 4.48 kg ai/ha controlled red rice ecotypes 92 to 100% and cultivars ‘Lemont,’ ‘Mars,’ and ‘Maybelle’ 39 to 63%. Red rice control with thiobencarb at 4.48 kg ai/ha was at least 89%. The tank mixture of fenoxaprop at 0.08 kg ai/ha plus fluazifop-P at 0.10 kg ai/ha controlled red rice and rice cultivars more than for either herbicide applied alone. Red rice and rice cultivar control with paraquat at 0.70 kg ai/ha was 83 to 100%. Blackhulled red rice TX 4 was less sensitive to paraquat and glufosinate than other ecotypes and cultivars. Glufosinate at 1.12 kg ai/ha was required to provide at least 94% control of ecotype TX 4.