Distribution of maize lethal necrosis epidemics and its association with cropping systems and cultural practices in Ethiopia

Four hundred thirteen fields in five 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 significantly 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 significant association with MLN disease epidemics. This study indicated that MLN disease is a major maize production constraint in Ethiopia. The findings 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.