Glufosinate at 2.2 kg ai/ha injured rice transformed with the BAR gene more when applied to one- to two-leaf (23 to 26%) than to three- to four-leaf (13 to 19%) plants. Visible injury was least when applications were made at boot stage (3 to 14%). However, applications at boot stage caused an average grain yield reduction of 16%. Most treatments did not influence rice plant height. Among single applications (0.3, 0.4, 0.6, 0.8, and 1.1 kg/ha), 1.1 kg/ha glufosinate at three- to four-leaf stage of red rice resulted in greater control (91%) than at panicle initiation (74%) or at boot stage (77%). Injury to red rice was two to 11 times greater than the injury to BAR-transformed rice depending on glufosinate rate and application timing.

Field studies were conducted in 1996, 1998, 1999, and 2000 to determine the effect of glyphosate (isopropyl amine salt) on rice injury and yield when applied postemergence at 0, 70, 140, and 280 g ai/ha to dry-seeded rice in the three- to four-leaf (3- to 4-L), midtiller (MT), panicle initiation (PI), and boot (BT) growth stages. Glyphosate at 140 and 280 g ai/ha applied at the 3- to 4-L, MT, and PI growth stages resulted in the greatest foliar injury, and 280 g ai/ha was more injurious than 140 g ai/ha at the first rating, with the exception of MT and PI 2000, where they were equal. Glyphosate treatments resulted in the least visible foliar injury when applied at the BT stage. Rough rice yield was reduced by glyphosate applied at 280 g/ha to rice in the MT growth stage three out of four years. Applied to rice at PI, glyphosate at 140 g/ha reduced yields two out of four years, and three out of four years when applied at 280 g/ha. BT-stage applications of glyphosate at 70, 140, and 280 g/ha reduced yields two out of four, three out of four, and four out of four years, respectively.