Dry season and soil texture affect the chemical control of Senna obtusifolia in sugarcane

Abstract

Because of its intrinsic characteristics, sicklepod (Senna obtusifolia) has gained importance in sugarcane, especially where there is a predominance of straw after mechanical harvest. The objective of this study was to evaluate the efficacy of preemergence herbicides used in sugarcane to control sicklepod in different soil textures and application timings. Two experiments were carried out for each application season (dry and wet), and one experiment for each soil textural class (clay and sandy clay loam), totaling four experiments. The treatments consisted in 17 herbicides in the wet season and 11 herbicides in the dry season (all herbicides were applied at 50 and 100% of the recommended dose) and a check without application for each season and soil, and the design was completely randomized. Soil texture and application timing have altered the herbicide efficacy. For the wet season, initially, all herbicides, except trifluralin and s-metolachlor, resulted in satisfactory control of sicklepod. Tebuthiuron was the herbicide that provided the longest period of residual control. For the dry season, amicarbazone, flumioxazin, hexazinone, imazapic, [diuron + hexazinone] F1 and isoxaflutole were efficient in both soils, but only in initial evaluations; [diuron + hexazinone] F1 and amicarbazone were the herbicides that provided the longest period of residual control.