Two experiments were conducted under greenhouse conditions to identify, based on dose-response curves, the sensitivity of young and perennial plants of West Indian Marsh grass to increasing doses (0, 25, 50, 75, 100, 125, 150, 175 and 200% of the recommended dose for perennial grasses) of cyhalofop butyl (315gc.p. ha-1), imazapic + imazapyr (24.5gc.p. ha-1 + 73.5gc.p. ha-1), glyphosate (2,160gc.p. ha-1) and ammonium glufosinate (900gc.p. ha-1). Experiment I was conducted from January to March 2010 and Experiment II, from January 2010 to January 2011. Young plants showed higher sensitivity to ammonium glufosinate and cyhalofop butyl; however, death occurred only when the plants were treated with glyphosate and a formulated mixture of Imazapic + Imazapyr. The herbicides did not provide satisfactory control against the perennial plants.
flooded rice; chemical control; Hymenachne amplexicaulis
