During the 2005 Spring-Summer growing cycle, three experiments were established in Ursulo Galvan, Ver., Mexico, to determine the best time of application of the herbicide amicarbazone in irrigated sugarcane, and the susceptibility of the three main varieties grown in this state to this herbicide. In one experiment, weed control of amicarbazone at 0.7, 1.05 and 1.4 kg ha-1 applied at four stages (pre-emergence before germination irrigation, pre-emergence after germination irrigation, early post-emergence and late post-emergence) was evaluated. In the other experiments, the toxicity of amicarbazone at 0, 0.7, 1.4 and 2.1 kg ha-1 was evaluated when applied at pre-emergence and post-emergence on sugarcane varieties Mex 69-290, CP 72-2086 and 79 Mex-431. Amaranthus lividus was better controlled with post-emergence applications of amicarbazone, starting at 0.7 kg ha‑1. Control of Guinea grass (Megathyrsus maximus) was low with amicarbazone at all stages. In pre-emergence applications, amicarbazone up to 2.1 kg ha-1 was highly selective to all varieties evaluated, whereas when applied in post-emergence, it caused slight toxicity to the three sugarcane varieties, increasing as the dose increased. However, the damages disappeared between 30 and 45 days after application, without causing a permanent reduction in plant height.
weed control; pre-emergence; post-emergence; Saccharum officinarum; Amaranthus lividus; Megathyrsus maximus
