Profiles of herbicide resistance in sub-Saharan Africa

Weed infestations continue to pose a to crop productivity and food security across sub-Saharan Africa (SSA), with yield losses reaching 90% in some regions. Although herbicide use has grown substantially, particularly in maize-based systems, manual weeding remains the primary method of weed control for over 80% of smallholder farmers, leading to labour bottlenecks and delayed weed suppression. Herbicides offer a viable alternative to manual labour, yet their unregulated and repetitive use, often involving herbicides with similar modes of action, has intensified the global problem of herbicide resistance. Since 1957, the number of herbicide-resistant weed species has surged from just two to over 500 by 2020, threatening the sustainability of chemical weed control. This review critically analyses evolving herbicide use patterns and emerging herbicide resistance in SSA. The review also identifies a set of urgent, interlinked challenges related to increasing herbicide dependency, weak regulatory oversight, inadequate resistance surveillance, low uptake of integrated weed management (IWM), and the growing problem of herbicide resistance across the region. These trends parallel the historical trajectories observed in countries like Australia and the United States, where intensive herbicide reliance has led to entrenched resistance problems. Drawing on comparative lessons from these global contexts, the review proposes a suite of sustainable weed management strategies tailored to SSA’s agro-ecological and socio-economic realities. These include strengthening regulatory frameworks, institutionalising herbicide resistance monitoring, and mainstreaming IWM within national agricultural policies. Without coordinated, forward-looking interventions, SSA risks repeating the unsustainable pathways that have undermined herbicide efficacy elsewhere.