Community-survey based assessment of the geographic distribution and impact of maize lethal necrosis (MLN) disease in Kenya

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Maize Lethal Necrosis (MLN) is a viral maize disease that suddenly appeared in Kenya in the last few years and is causing major damages. Interventions are urgently needed, but information is lacking on its geographic distribution and losses caused. Group discussions were held in 2013 in 121 sublocations in the major maize zones, and respondents were asked if they had heard about MLN, when they first observed it, the proportion of households affected, and the estimated yield loss in affected areas. Responses were used to estimate the proportion of maize lost in the community, and these results were interpolated and combined with maize production data to estimate quantities lost. Western Kenya suffered most with more than half of farmers affected, followed by Central and Eastern Kenya, with up to a third of farmers. Yield losses in affected areas were highest in Western Kenya, followed by the highlands (in Central Kenya and the Rift Valley) and at the coast, but were low in the drylands (in Eastern Kenya). Total maize losses in Kenya were estimated at 0.5 million ton per year, or 22% of the average annual production before MLN, with a value estimated at $180 million. Losses were concentrated in Western Kenya, in particular the moist transitional zone (58% of all maize lost) and the moist mid-altitudes (19%), but also in the highlands (17%). Losses were small in the drylands and at the coast. Urgent action is needed to help farmers cope. In the short term, they need to be informed about the disease and provided with advice on appropriate agronomic practices. In the long term, varieties resistant to MLN need to be developed, first for the moist transitional and moist mid-altitude zones and followed by the highlands, but ultimately for all agroecological zones.