Adjuvants, Cyperus spp., Glyphosate, Glyphosate + ammonium sulphate, Weed management

A field study was conducted in the Vertisols of South Gujarat to evaluate the efficacy of glyphosate-adjuvant combinations against a complex weed flora dominated by perennial sedges. The uniform pretreatment weed flora in the experimental area includes: Cyperus rotundus, Echinochloa crus-galli and Trianthema portulacastrum. Assessment revealed significant variation in mortality and regrowth of Cyperus spp. at 40 days after application (DAA). Glyphosate + ammonium sulphate (1.5 kg/ha + 2%) recorded complete mortality (100.0%) of Cyperus spp., and was statistically at par with glyphosate + 2,4-D (99.52%) and glyphosate + sugar (99.14%). Mechanical inter-culturing was ineffective as rhizome fragmentation triggered dormant bud release and caused a regrowth surge, while glyphosate + ammonium sulphate recorded minimum regrowth of Cyperus spp. Economic analysis at 40 DAA indicated glyphosate + ammonium sulphate and glyphosate + 2,4-D as the most viable strategies achieving the highest Cyperus control efficiency (>72%) with the lowest cost per percent control. The growth and yield parameters of the successively grown blackgram confirmed the lack of any significant residual effect from the applied herbicides. Thus, for the sustainable management of tuberous perennials, the adjuvant augmented glyphosate was found significantly more effective than traditional mechanical methods.