Maize lethal necrosis (MLN), an emerging threat to maize-based food security in sub-Saharan Africa

Authors: MAHUKU, GEORGE - International Maize & Wheat Improvement Center (CIMMYT); LOCKHART, BENHAM - University Of Minnesota; WANJALA, BRAMWEL - Kenya Agricultural And Livestock Research Organization; Jones, Mark; KIMUNYE, JANET - International Maize & Wheat Improvement Center (CIMMYT); Stewart, Lucy; CASSONE, BRYAN - The Ohio State University; SEVGAN, SUBRAMANIAN - International Centre Of Insect Physiology And Ecology; JOHNSON, NYASANI - International Centre Of Insect Physiology And Ecology; KUSIA, ELIZABETH - International Centre Of Insect Physiology And Ecology; KUMAR, LAVA - International Institute Of Tropical Agriculture (IITA); NIBLETT, C - Venganza Inc; WANGAI, ANNE - Kenya Agricultural And Livestock Research Organization; KIGGUNDU, ANDREW - National Agricultural Research Organization - Uganda; ASEA, GODFREY - National Agricultural Research Organization - Uganda; PAPPU, HANU - Washington State University; PRASANNA, BODDUPALLI - International Maize & Wheat Improvement Center (CIMMYT); Redinbaugh, Margaret

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2015
Publication Date: 7/1/2015
Publication URL: http://handle.nal.usda.gov/10113/61303
Citation: Mahuku, G., Lockhart, B.E., Wanjala, B., Jones, M.W., Kimunye, J.N., Stewart, L.R., Cassone, B.J., Sevgan, S., Johnson, N., Kusia, E., Kumar, L., Niblett, C.L., Wangai, A., Kiggundu, A., Asea, G., Pappu, H., Prasanna, B.M., Redinbaugh, M.G. 2015. Maize lethal necrosis (MLN), an emerging threat to maize-based food security in sub-Saharan Africa. Phytopathology. 105:956-965.

Interpretive Summary: In sub-Saharan Africa, corn or maize is a staple food that is used as food by small farmers. In this region, which includes Ethiopia, South Sudan, Kenya, Uganda, Tanzania, Rwanda, Burundi and from the Democratic Republic of the Congo, pest and disease outbreaks are key constraints to maize productivity and food security. In September 2011, a serious disease outbreak, later diagnosed as maize lethal necrosis (MLN), was reported on maize in Kenya. The disease has since been confirmed or reported from all of these countries, where farmers can lose up to 90% of their crop. MLN is caused by infection of maize with two viruses named Maize chlorotic mottle virus (MCMV) and Sugarcane mosaic virus (SCMV). In this article, we summarize here the results of collaborative research undertaken to understand the pathogens that cause MLN, and how they spread among plants. We also describe our initial efforts to identify maize that is tolerant or resistant to the viruses that cause MLN. In addition to outlining our research progress, we outline the major remaining research questions and the next steps to take to develop effective management strategies to control MLN.

Technical Abstract: In sub-Saharan Africa, maize is a staple food and key determinant of food security for smallholder farming communities. Pest and disease outbreaks are key constraints to maize productivity. In September 2011, a serious disease outbreak, later diagnosed as maize lethal necrosis (MLN), was reported on maize in Kenya. The disease has since been confirmed in Rwanda and the Democratic Republic of Congo, and similar symptoms have been reported in Tanzania, Uganda, South Sudan, and Ethiopia. In 2012, yield losses of up to 90% resulted in an estimated grain loss of 126,000 metric tonnes valued at $52 million in Kenya alone. In eastern Africa, MLN was found to result from co-infection of maize with Maize chlorotic mottle virus (MCMV) and Sugarcane mosaic virus (SCMV), although MCMV alone appears to cause significant crop losses. We summarize here the results of collaborative research undertaken to understand the biology and epidemiology of MLN in East Africa and to develop disease management strategies, including identification of vectors, epidemiology and MLN tolerant maize germplasm. We discuss recent progress, identify major issues requiring further research and discuss the possible next steps for effective management of MLN.