Sequential and ready-mix herbicides for effective and economical weed management in groundnut under the central dry zone of Karnataka

Abstract

Groundnut is highly vulnerable to weed competition during its early growth stages due to slow initial development, short canopy and rainy-season cultivation, resulting in severe reductions in growth and yield. To identify effective and economical weed management strategies, a field experiment was conducted during the rainy season of 2024 at Hiriyur, Karnataka, using nine treatments including pre-emergence, post-emergence and ready-mix herbicides, a sequential herbicide program and manual weeding, arranged in a randomized complete block design. The study evaluated their influence on weed density, weed control efficiency, growth attributes, dry matter accumulation, pod and haulm yield, economics and residual impact on the succeeding soybean crop. The dominant weed flora comprised grasses, broad-leaved weeds and sedges. Weed density at sixty days was lowest under manual weeding at twenty and forty days, followed closely by the sequential application of diclosulam followed by fenoxaprop-p-ethyl and by pendimethalin followed by quizalofop-p-ethyl. These treatments also recorded the highest weed control efficiency. Superior weed suppression resulted in significant improvements in plant height, branching, leaf area index and dry matter accumulation. The highest pod and haulm yields were obtained under manual weeding, while the sequential diclosulam protocol produced statistically similar yields with substantially lower labour cost. Ready-mix herbicides such as fluazifop-butyl plus fomesafen and pendimethalin followed by quizalofop-p-ethyl also provided broad-spectrum control and improved crop performance compared to the untreated check. Economic analysis revealed that the diclosulam followed by fenoxaprop-p-ethyl strategy achieved the greatest net returns and benefit-cost ratio, making it the most profitable option. Assessment of the succeeding soybean crop indicated no residual phytotoxicity, as germination remained uniform across treatments. Overall, the results highlight that while manual weeding ensures excellent weed control, the sequential diclosulam-based herbicide strategy offers an equally effective and more economical alternative and ready-mix herbicides provide viable broad-spectrum solutions for integrated weed management in groundnut under rainfed conditions of the Central Dry Zone of Karnataka.