Weed control and selectivity of herbicide mixtures in upland cotton

Abstract

In order to study the efficiency of herbicide tank mixtures against weed and their effects on annual cotton (Gossypiumhirsutum L. r. latifolium Hutch.) cultivar PR 4139, a trial was placed at Iguatu, CE, Brazil, in 1983. The herbicides used were metholachlor, pendimethalin, alachlor, cyanazine, and diuron. The results showed that the cultivar tested PR 4139 was resistant to the rate of herbicides and the mixtures were effective in weed control until the 60 days after the cotton emergence. The most efficient control was obtained by the mixtures containing metholachlor + diuron (1.30 l + 0.96 kg of a.i./ha); metholachlor + cyanazine (1.30 l + 0.63 kg of a.i./ha); pendimethalin + diuron (0.70 l + 0.96 kg of a.i./ha); alachlor + diuron (0.58 l + 0.96 kg of a.i./ha) and alachlor + pendimethalin + diuron (0.29 l + 0.34 l + 1.00 kg of a.i./ha. The predominant weeds were: Eleusine indica (L.) Gaertn. Digitaria horizontalis Willd., Cenchrus echinatus L., Acanthospermum hispidum D.C., Amaranthus spinosus L. and Sida rhombifolia L.