Tolerance of two cotton varieties to herbicides applied in pre-emergence

Abstract

This work aimed to evaluate the selectivity of herbicides applied pre-emergence, isolated or in tank-mixtures, for two cotton varieties, Delta-Opal and FMT-701. Treatments applied were: alachlor, S-metolachlor, diuron (two rates), prometryn (two rates), oxyfluorfen, alachlor + diuron, alachlor + prometryn (two rates of this mixture), S-metolachlor + diuron, S-metolachlor + prometryn (two rates of this mixture), oxyfluorfen + diuron, oxyfluorfen + prometryn. Evaluations performed were related to the visual plant intoxication, height of plants and crop yield. When rates of diuron and prometryn were increased, symptoms of crop injury were also more evident, in relation to lower rates of the same products. Oxyfluorfen, isolated or in tank mixture with diuron or prometryn propitiated intense symptoms of crop injury, but the only treatment which was considered as non-selective for both cotton varieties was the mixture of oxyfluorfen + prometryn (0.192 + 0.9 kg ha^-1).