Biology, Epidemiology, Economic Importance and Management of Maize Lethal Necrosis Disease (MLND) in Ethiopia: A Review

Abstract

Maize (Zea mays L.) is an economically, nutritionally, and industrially pivotal cereal crop globally. Ethiopia is the second-largest maize producer in Sub-Saharan Africa, where the crop serves as a primary staple for millions of smallholder farmers across diverse agro-ecologies. Despite its importance, production is severely constrained by a complex matrix of biotic and abiotic factors. Among the biotic constraints, Maize Lethal Necrosis Disease (MLND) has emerged as the most destructive transboundary viral threat to maize productivity in the region. This review aims to assess the occurrence, biological mechanisms, epidemiology, economic impact, and management strategies of MLND in Ethiopia. Data were consolidated from peer-reviewed journals, doctoral dissertations, technical reports, and international symposia proceedings. Findings indicate that MLND causes catastrophic grain yield losses ranging from 50% to 100%. The disease is driven by a unilateral synergistic co-infection where SCMV suppresses the host's innate immune system via RNA silencing interference, leading to hyper-accumulation of MCMV. Epidemiology is primarily governed by thrips (Frankliniella spp.) and aphid (Rhopalosiphum spp.) vectors, supplemented by low-rate seed transmission, which facilitates long-distance dissemination. Effective mitigation requires an Integrated Disease Management (IDM) framework involving rigorous phytosanitary protocols, synchronised crop rotation, targeted vector control, and the deployment of resistant hybrids developed through marker-assisted breeding. This review concludes that while MLND poses a critical threat to national food security, its impact can be mitigated through the strategic integration of host resistance and optimised cultural practices.