RED RICE (ORYZA-SATIVA) CONTROL AND SEEDHEAD REDUCTION WITH GLYPHOSATE

Glyphosate was evaluated at 0.8, 1.3, and 1.7 kg ae/ha applied at the two-leaf, four-leaf, or two- to three-tiller growth stage for red rice control. In addition, red rice seedheads were counted concurrently wi th soybean harvest at each of three locations to assess treatment effe ct on seedhead reduction. Field studies were conducted at Starkville, MS, in 1994 and 1995 and Shaw, MS, in 1995, A significant rate respons e was not observed for red rice control 2 and 4 wk after treatment (WA T) or for seedhead reductions. Glyphosate controlled red rice 88, 91, and 88% 2 WAT when applied to two-leaf, four-leaf, or two- to three-ti ller red rice, respectively. Due to subsequent seedling emergence, con trol from glyphosate applications to two- or four-leaf red rice 4 WAT was 51 and 84%, respectively. Red rice treated at the two- to three-ti ller stage was controlled 91% 4 WAT. When compared to the nontreated c ontrol, seedheads were reduced 97% by two- to three-tiller application s, compared to 87 and 56% reductions from four- and two-leaf applicati ons, respectively.