Ecological weed management in Sub-Saharan Africa: Prospects and implications on other agroecosystem services

Abstract

Abstract In Sub-Saharan Africa weeds represent a major constraint to food production, and overreliance on herbicides, including toxic ones, is a raising issue. Nonetheless, effective non-chemical weed management practices are adopted by several Sub-Saharan farmers, and may foster ecological intensification and agroecological crop management in the region. Ecological Weed Management (EWM) is a combination of methods aimed to achieve long-term weed suppression through the use of ecological interactions between crop, weeds, soil and/or other taxa fostered by appropriate agroecosystem management, with the least possible use of direct weed control methods, chemical or non chemical. The opportunities offered by EWM in Sub-Saharan Africa are synthesized based on results of a comprehensive literature review. Ecological Weed Management of Striga spp., emblematic parasitic weeds in the area, is treated in details showing that effective methods exist and often work better when combined. These methods include, e.g., the development of cultivars resistant or tolerant of infection, improved crop rotations, cover crops, intercrops and mulches, other soil-based positive interactions, and biocontrol via use of pathogenic fungi. Strategies including functional biodiversity-based methods are expected to foster EWM and overall agroecological crop management in the region. EWM methods can support other agroecosystem services (e.g., soil fertility) and at the same time be improved by methods aiming at other services (e.g., push-pull strategies against maize cob borers). Transdisciplinary collaboration and scientists' engagement in participatory research and action with farmers and other stakeholders would be instrumental to facilitate broader adoption of EWM in Sub-Saharan Africa.