Maize lethal necrosis

Maize lethal necrosis
Name	Maize lethal necrosis
Specialist	Virology, Plant pathology
Symptoms	Leaf necrosis, stunting, chlorosis
Hosts	Maize (Zea mays)
Causal agents	Potyviridae and Tombusviridae family viruses
Vectors	Aphids, thrips, beetles, mechanical transmission
Distribution	Africa, Asia, Americas

Maize lethal necrosis

Introduction

Maize lethal necrosis is a destructive disease affecting Zea mays with rapid collapse and yield loss first noted in outbreaks associated with global crop movements involving International Maize and Wheat Improvement Center, Food and Agriculture Organization, International Fund for Agricultural Development, Bill & Melinda Gates Foundation, and national research programs such as Kenya Agricultural and Livestock Research Organization, International Institute of Tropical Agriculture, and CIMMYT. The syndrome has drawn attention from organizations including United States Department of Agriculture, International Food Policy Research Institute, World Bank, African Union, and regional governments in Ethiopia, Kenya, Rwanda, Tanzania, China, United States, and Brazil because of impacts on smallholder farmers and commercial producers.

Causal agents and virology

The disease results from synergistic co-infection by viruses typically belonging to families such as Potyviridae (often a potyvirus like Maize dwarf mosaic virus) and Tombusviridae (often a maize-infecting virus such as Maize chlorotic mottle virus), a phenomenon studied by virologists at institutions like University of California, Davis, Iowa State University, Wageningen University, University of Cambridge, and John Innes Centre. Molecular characterization has involved labs using techniques developed at Sanger Institute, Broad Institute, Cold Spring Harbor Laboratory, Max Planck Institute for Plant Breeding Research, and EMBL to sequence RNA genomes, analyze coat proteins, and study interactions with host factors such as those described in research from Massachusetts Institute of Technology, Harvard University, and University of Oxford. Vector relationships implicate hemipteran and thysanopteran insects investigated in projects funded by Bill & Melinda Gates Foundation, UK Research and Innovation, and National Science Foundation.

Symptoms and diagnosis

Field symptoms include rapid necrosis, chlorotic streaking, and severe stunting observed across diverse agroecosystems monitored by extension services in Ministry of Agriculture (Kenya), USDA Agricultural Research Service, International Center for Tropical Agriculture, Nepal Agricultural Research Council, and Brazilian Agricultural Research Corporation (Embrapa). Diagnostic confirmation uses serological assays (ELISA) and molecular tests (RT-PCR, next-generation sequencing) performed at laboratories such as FIOCRUZ, CSIRO, Institut Pasteur, Johns Hopkins Bloomberg School of Public Health, and regional diagnostic centers supported by FAO and WHO collaborations. Differential diagnosis considers other threats documented by agencies like CropLife International, African Development Bank, and Asian Development Bank.

Epidemiology and spread

Epidemiological patterns have been mapped using tools from NASA remote sensing collaborations, geospatial analyses shared with European Space Agency, and outbreak reporting coordinated via Food and Agriculture Organization and national plant protection organizations including Kenya Plant Health Inspectorate Service and United States Animal and Plant Health Inspection Service. Spread occurs through insect vectors common in landscapes managed by producer groups supported by Heifer International, Oxfam, and USAID, via infected seed movement tracked in studies by CIMMYT, ICRISAT, and regional seed systems such as those in Uganda, Mozambique, and Zambia. Climate influences have been modeled by teams at Intergovernmental Panel on Climate Change, Met Office, and university climate centers at Columbia University and University of Reading.

Management and control

Integrated management strategies promoted by FAO, CGIAR, CABI, Syngenta Foundation, and national extension networks emphasize certified seed programs run with support from Bill & Melinda Gates Foundation and regulatory frameworks influenced by International Plant Protection Convention and National Seed Trade Associations. Cultural practices include crop rotation and weed control advocated by researchers at University of Illinois Urbana-Champaign, North Carolina State University, and University of Pretoria》, while vector control options evaluated by trials at IRRI, CIAT, and private sector partners such as Bayer and Syngenta use insecticide stewardship and integrated pest management principles from FAO guidelines. Quarantine, seed certification, and rapid diagnostic deployment are coordinated with agencies including USDA APHIS, European Commission, and national ministries of agriculture.

Economic impact and importance

Outbreaks have caused devastating yield losses with socioeconomic analyses published by World Bank, International Monetary Fund, IFPRI, and academic teams at University of California, Berkeley, University of Michigan, and London School of Economics. Impacts are particularly severe for smallholder farmers in regions supported by African Union, NEPAD, USAID Feed the Future, and development NGOs such as Care International and Save the Children, affecting food security, trade patterns reported by World Trade Organization, and national statistics offices in Kenya Bureau of Statistics, Ethiopia Central Statistical Agency, and National Bureau of Statistics (Tanzania).

Research and breeding efforts

Breeding for resistance and tolerance is led by programs at CIMMYT, IITA, IRRI, CIAT, and national agricultural research systems like Kenya Agricultural and Livestock Research Organization and Ethiopian Institute of Agricultural Research, often in partnership with universities including Cornell University, University of Wisconsin–Madison, Punjab Agricultural University, and private companies such as DuPont Pioneer and BASF. Genomic selection, marker-assisted breeding, and transgenic or gene-editing approaches have been explored with resources from Gates Foundation, BBSRC, NSF, and collaborations with sequencing centers like Sanger Institute and Broad Institute. International workshops and networks hosted by FAO, CGIAR, ISAAA, and African Union Commission coordinate germplasm exchange, phenotyping trials, and capacity building.

Category:Maize diseases