Enhancing productivity of sugarcane by successful weed management through integration of brown manuring of Sesbania and pre and post emergence herbicides

Field experiments were conducted to evaluate the combined effect of brown manuring with post emergence herbicide on weed management in planted sugarcane. Weeds are one of the major biotic stress and its management was the very costliest agronomic input in the successful crop production. Weeds can cause yield reduction in sugarcane up to 40%. Indiscriminate use of herbicides can accelerate weed flora shift and resistance besides causing environmental pollution and non-target toxicities and. Brown manuring is a no till version of green manuring using a post emergence herbicide. For brown manuring, Sesbania is grown as intercrop with sugarcane for initial 35 days, and then, is knocked down by 2,4-D. BM had multiple benefits including weed management. In Sugarcane its wider inter row space and its initial slow growth would allow to formulate an integrated weed management (IWM) module with brown manuring and herbicide. Therefore, this experiment was undertaken at Agricultural Collage and Research Institute, Madurai during 2016 to 2018 to evaluate the integrated effect of brown manure and herbicide on weed management in sugarcane. Among nine treatments, three were BM of sesbania and three were in- situ incorporation of sesbania, involving one intercultural operation at 90 DAP (Hand hoeing; Metribuzin: halosulfuron application). In addition, three controls, namely atrazine 1 kg /ha + power weeeding at 45 & 75 DAP, hand weeding twice and unweeded control were also adopted and the experiment was laid out in a randomized block design with three replications. A pre-emergence application of pendimethalin 2.0 kg/ha was made in all sesbaniarasied treatments. The results showed that application of pendimethalin 2.0 kg ha-1 + Sesbania (brown manuring) + hand hoeing at 90 DAP recorded minimum number of weeds and weed dry weight. The higher weed control efficiency (78.96%), cane yield (100.5 t /ha) and benefit cost ratio (2.72) were found with PE application of Pendimethalin + Sesbania(Brown manuring) + hand hoeing at 90 DAP compared to POE herbicides and insitu incorporation of Sesbania.