Competi??o de misturas de herbicidas nas principais regi?es algodoeiras (Gossypium hirsutum L.) no E. de Minas Gerais

摘要

Several herbicide mixtures were tested on cotton, (Gossypium hirsutum L.) in the main production areas of the State of Minas Gerais, Brasil. The cultivar "Minas Dona Beta", was used in the Metalúrgica region, whilst in Triângulo and Norte the cultivar employed was ."IAC-13-1", . In Triângulo litle regrowth occurred up to 30 days after application when the following mixtures were used: dinitramine + diuron, dinitroanilin + prometryne and pendimethalin + diuron. These treatments controlled 96.2%, 92.5% and 96.5% of the total weeds, respectively. When yields were compared, 1,962 Kg/ha were obtained in the best treatment (pendimethalin + diuron), against the control plots average of 1,130 Kg/ha. Tank mixtures of 2,00 Kg/ha of alachlor and 0.35 Kg/ha of metribuzin, or 3,00 Kg/ha of alachlor and 0,50 Kg/ha of metribuzin, and 1,00 Kg/ha of trifluralin and 0,50 Kg/ha of metribuzin were the most efficient in controlling grasses and dicotyledons. Effective weed control was recorded in Nor th of Minas Gerais when pendimethalin + diuron were applied expressed as: 86.4%, 83.6% and 70.3% of the total weeds after 30,50 and 80 days, respectively. The mixtures dinitramine + fluome - turon and dinitroanilin + fluometuron showed the best results regard to a cotton yield of 1,532 Kg/ha, produced in the treated plots against only 229 kg/ha in the control (unhoed). The best combination for total weed control in the Metalúrgica region was dinitramine + diuron with an efficiency of 67% after 30 days. When differences in fiber production were considered, however, the best mixture was dinitramine + fluometuron, the treated plots yielding 831 kg/ha and the control 145 kg/ha.