Maize Lethal Necrosis Disease in Ethiopia: A Newly Emerging Threat to Maize Production

Abstract

The occurrence of maize lethal necrosis (MLN) disease in Ethiopia was first reported in 2014. Thereafter, consecutive surveys were carried out in all majormaize growing areas across the country to understand the levels of distribution and incidence as well as potential alternate hosts of the disease.  Symptomatology was used to determine the incidence and level of damage caused by MLN at the field level. Samples of maize plants and alternative  grass hosts showing MLN symptoms were collected in all areas surveyed. Viruses associated with the symptoms were diagnosed in the laboratory using  Enzyme-Linked Immunosorbent Assay (ELISA), Lateral Flow Assay (LFA), Real Time-Polymerase Chain Reaction (RT-PCR), Multiplex RT-PCR, and RT-PCR  using porous ceramic cube. The results showed a wider distribution of MLN in Ethiopia with incidence levels reaching as high as 100% in some areas.  Maize planted during the off-season were found to be severely affected by MLN as compared to the main season crop. In addition to maize, MLN viruses  were found to infect various grass species indicating the presence of alternate hosts. This study confirmed seed transmission of MLN disease, but  variable rates of transmission were observed that needs to be studied further. Considering the current rate of MLN disease distribution in Ethiopia,  necessary management strategies should be devised and implemented before the disease causes significant damage to maize production.