Document Type : Pest Management
Author
Abstract
In Golestan province, three field trials were conducted to evaluate the efficacy of pre-emergence herbicides diuron, prometryn and alachlor, respectively at 2, 2 and 1.92 kg ai ha-1, in control of weeds and their selectivity on cotton (Sahel cultivar). In the first experiment (first year), the herbicides were used alone or tank mixed with each other to compare them with weedy check and weed-free check. In the two other experiments (second year), the efficacy of broadcast and band application of diuron and prometryn was evaluated. In the second year experiments, inter-row cultivation was carried out one month after planting in all treatments except in weedy check. In band application, the application rate of the herbicides was reduced to 50%. In all experiments, the herbicides caused no visual injuries on cotton cv. Sahel and all treatments, compared with weedy check, significantly controlled the weed species. In control of Amaranthus retroflexus, Chenopodium album, Solanum nigrum and Abutilon theophrasti, diuron and prometryn were better than alachlor. Whereas, the effect of alachlor on Echinochloa crus-galli, was better than that of the other herbicides. Diuron was significantly more effective in control of S. nigrum than prometryn. Despite inter-row cultivation, band application of diuron or prometryn was less effective than broadcast application in control of S. nigrum, A. retroflexus and A. theophrasti. Broadcast application of diuron or prometryn, accompanied with inter-row cultivation, in addition to sufficient control of weeds, resulted in higher cotton lint yield than the other treatment. Cotton lint yield loss in weedy checks in the experiments was evaluated 54 to 95 percent
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