Evaluation of the efficiency on the control of gramineous weeds by the herbicide clethodim in a herbaceous cotton crop (Gossypium hirsutum var. latifolium Hutch.)

摘要

An experiment in the Porteirinha region, north of Minas Gerais state, Brazil, was performed with the cotton cultivar IAC-20 to find out the efficiency of clethodim 0.84, 0,96 and 0,108 kg/ha plus 0.5% mineral oil v/v, in comparison to sethoxidim 0.23 kg/ha plus 0.5% mineral oil v/v, all those treatments in post emergence; other treatments were in preplanting time and incorporated to the soil alachlor 2,4 kg/ha and trifluralin 0.89 kg/ha; as check were used no weeded plots and hoed plots. The weeds involved were Cenchrus echinatus L., Eleusine indica (L.) Gaertn. And Brachiaria plantaginea (Link.) Hitch. None of the tested herbicides were noxious to the cotton plants. The highest production in cotton was obtained from the check hoed plots (828 kg/ha); in the second place the clethodim 0.108 kh/ha gave 528 kg/ha, the only treatments statistically different from the no weeded plots wich gave 330 kg/ha. Clethodim gave good control of Cenchrus echinatus and Eleusine indica, with all doses. Brachiaria plantaginea was efficiently controlled (86% and more) by clethodim. Clethodim followed by sethoxydim gave in general 83% and 85% control of all the grasses.