Weed control in transplanted rice with post-emergence herbicides and their effects on subsequent rapeseed in Eastern India

Abstract

Effective broad-spectrum herbicides are needed to address the issues of herbicide resistance and weed shifts in common cropping systems. A field experiment was conducted in 2016 and 2017 in West Bengal, India to compare the performance of three post-emergence herbicides (bispyribac-sodium; fenoxaprop-p-ethyl; penoxsulam) in monsoon rice (Oryza sativa L.) and their residual effects on succeeding rapeseed (Brassica rapa L.). Rice yield loss due to competition with Echinochloa colona (L.) Link, Leersia hexandra Sw., Cyperus iria L., Ludwigia parviflora L., and Monochoria vaginalis (Burm f.) C. Presl. Ex Kunth was 64% compared with weed-free control. Bispyribac-sodium 10% SC applied at 30 g a.i. ha⁻¹ 20 days after transplanting reduced weed density over the weedy control, ranging from 37% (M. vaginalis) to 87% (L. hexandra). Fenoxaprop-p-ethyl and penoxsulam applied, respectively, at 86 and 20 g a.i. ha⁻¹ were effective in controlling grasses, but less effective against sedges and broadleaves. Bispyribac-sodium application resulted in highest rice yield (5.45 t ha⁻¹), net return (Indian Rupees 42,677 ha⁻¹), and benefit cost ratio (1.72). Bispyribac-sodium had neither adverse effect on soil microbes nor phytotoxic effect on rice and subsequent rapeseed. We recommend bispyribac-sodium for weed control in transplanted rice under rice-rapeseed system in eastern India.

Keywords:

• Bispyribac-sodium
• fenoxaprop-p-ethyl
• penoxsulam
• weed control efficiency
• microbial population

Acknowledgements

The authors sincerely acknowledge the valuable comments and suggestions of all anonymous reviewers that helped us to improve the manuscript. The contribution of the Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal in terms of approving this research work and providing necessary facilities during the course of investigation is greatly acknowledged

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We gratefully acknowledge also the technical and financial support received from the Parijat industries (India) Pvt. Ltd., New Delhi 110048.