This paper examines the origins and impact of rapid recent growth of herbicide use in Mali. Primary data come from interviews with herbicide importers and distributors and from a 2014/2015 survey of farm households in Mali’s Sudanian Savanna zone. Results suggest that a series of major supply-side changes are driving growth in Mali’s herbicide markets, most conspicuously a proliferation in the number of sellers and herbicide brands marketed, a shift to low-cost suppliers in China and India, and consequently falling herbicide prices. At the farm level, herbicides cost on average 50 per cent less than hiring weeding labor. Despite low econometric estimates of damage abatement, herbicide adoption rates reach 25 per cent in remote rural zones and 75 per cent in more accessible rural areas. Key factors affecting adoption include spatial variation in herbicide prices and rural wage rates. At current levels, herbicide use reduces peak season rural labor demand by roughly 14 per cent.