Weed management research in India: An overview

Abstract

Weeds have been existent on earth ever since the man started cultivating/domesticating plants and animals around 10,000 B.C., which is called as the ‘dawn of civilization.’ The battle against weeds is a never ending one and often the costliest agronomic input for successful crop production. In India, weeds, generally, reduce crop yields by 36.5% during rainy-season and 22.7% during winter, and in some cases, cause complete crop failure. They decrease quality of farm produce (food, fibre, oil, forage/fodder), animal products (meat and milk) and cause health hazards for humans and animals. Besides, they, on an average, remove 30–40 kg N, 10–15 kg P2O5 and 2`0–40 kg K2O per hectare. Weeds are ubiquitous and their appearance/infestation is dynamic, which compels weed researchers to redesign strategies from time to time for successful weed management. Weed management methods, therefore, have evolved by phases in the world. Weed research carried out in India during last 50 years has been reviewed in this paper. Distribution, biology, ecology and management of several problematic weeds have been studied over the years. Mechanism and management of resistance in weeds, particularly in Phalaris minor Retz. (littleseed canarygrass) has been studied in depth. Enough studies have been undertaken on physical/mechanical, cultural/ecological, biological and chemical methods of weed control across locations. Advancement on weed management has been made in recent years in the form of integrated weed management (IWM). Majority of the researches focuses on herbicide-based IWM. Economic analysis revealed that the use of herbicide is more economical than mechanical/manual methods, but herbicide in combination with hand weeding is most economical. Future weed research in India should focus more on IWM for preventing shift and herbicide-resistance in weeds; invasive alien weeds; crop-weed-herbicide interactions under climate change; herbicide-tolerant crops (HTC); herbicide residues in soil, water and food chain; exploitation of weeds for beneficial use; and need for knowledge-based weed management decision-making tools and site-specific weed management.