Crop Protection 134 (2020) 105151 Available online 4 April 2020 0261-2194/© 2020 Published by Elsevier Ltd. Distribution of maize lethal necrosis epidemics and its association with cropping systems and cultural practices in Ethiopia Bayissa Regassa a, * , Adane Abraham b , Chemeda Fininsa c , Dagne Wegary d , Yitbarek Wolde-Hawariat e a Ambo Agricultural Research Center, Ethiopia Institute of Agricultural Research, P.O. Box 37, Ambo, Ethiopia b Department of Biotechnology, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia c Department of Plant Sciences, Haramaya University, P. O. Box 138, Dire Dawa, Ethiopia d CIMMYT-Ethiopia, P. O. Box 5689, Addis Ababa, Ethiopia e Department of Zoological Sciences, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia A R T I C L E INFO Keywords: Disease intensity Logistic regression Prevalence Zea mays ABSTRACT Four hundred thirteen felds in fve major maize growing regions of Ethiopia were surveyed to determine the prevalence, intensity and distribution of maize lethal necrosis (MLN) disease, and its associations with different maize cropping systems and cultural practices. The disease was most prevalent in South Nation, Nationality and Peoples (SNNP) region with 66.67% prevalence followed by Oromia region that had a prevalence of 65.62%. Similarly, MLN disease intensity and distribution varied among the regions surveyed, cropping systems and cultural practices used by the farmers. The associations of MLN disease intensity with independent variables were analyzed using logistic regression. Region, altitude, cropping season, cropping system, variety, insect vector, planting month and cropping year were signifcantly associated with high disease intensity of MLN in a multiple variable model. SNNP, Oromia and Benishangul-Gumuz regions, maize cultivated at altitudes of 900–1600 and 1700–2000 m.a.s.l, mono-cropping, presence of insect vectors, medium and high weed density and the 2015, 2016 and 2017 cropping years had a signifcant association with MLN disease epidemics. This study indicated that MLN disease is a major maize production constraint in Ethiopia. The fndings suggested that planting maize at the beginning of the main rainy season, proper weed management and crop rotation practices can minimize the negative impact of the MLN disease until resistant maize genotypes are developed and distributed to the farmers. 1. Introduction Maize (Zea mays L.) is the most important crop in terms of production and distribution in Ethiopia. Among cereals, maize ranks second to teff (Eragrostis tef) in area coverage with 2.13 million hectares, but frst in productivity (3.94 t ha 1 ) and grown by more than 10.5 million small- holder households, more commonly than any other crop in the country (CSA, 2018). Despite its importance, the average yield of maize in Ethiopia (3.9 t ha 1 ) is below the world average (5.6 t ha 1 ) (FAO, 2017). A signifcant portion of the yield gap is attributed to the effects of abiotic and biotic factors, and insuffcient use of varieties tolerant or resistant to these factors (Abate et al., 2017; Keno et al., 2018). The recently emerged maize lethal necrosis (MLN) disease further threatens maize production in the country. MLN disease that is caused by double infection of Maize chlorotic mottle virus (MCMV; genus Machlomovirus; family Tombusviridae) along with Sugarcane mosaic virus (SCMV; genus Potyvirus, family Potyviridae) is known to commonly occur on maize in Ethiopia (Mahuku et al., 2015; Fentahun et al., 2017). Even though SCMV is the most common virus in Ethiopia and other countries in East Africa, different members of the Potyviridae family, including Maize dwarf mosaic virus (MDMV) (Niblett and Clafin, 1978) or Wheat streak mosaic virus (WSMV) (Scheets, 1998) are also known to cause MLN disease by forming synergy with MCMV. In Africa, MLN was frst re- ported in 2011 in Kenya, causing extensive to complete yield losses (Wangai et al., 2012). It was frst reported in Ethiopia in 2014 (Mahuku et al., 2015). Since its occurrence in Ethiopia, MLN disease has become widespread and in some cases has lead to total crop failure (Fentahun et al., 2017; Guadie et al., 2018). * Corresponding author. E-mail address: bregassa2019@gmail.com (B. Regassa). Contents lists available at ScienceDirect Crop Protection journal homepage: www.elsevier.com/locate/cropro https://doi.org/10.1016/j.cropro.2020.105151 Received 22 November 2019; Received in revised form 13 March 2020; Accepted 14 March 2020