Managing the Maize Lethal Necrosis disease

Maize Lethal Necrosis (MLN) disease has continued to wreak havoc on maize production in East Africa since it was first reported in Kenya in 2011. Since then it has been reported in other eastern Africa countries.

The disease, caused by the combination of the Maize Chlorotic Mottle Virus (MCMV) and Sugarcane Mosaic Virus (SCMV), causes irreversible damage that kills maize plants leading to yield losses. MLN pathogens can be transmitted not only by insect vectors but also through contaminated seed.

Some developed countries have managed the disease through strategies that include combining tolerant varieties, crop rotation, and having maize free seasons to reduce the insect vector pressure that transmits the disease. However, in eastern Africa, the epidemic is aggravated by lack of MLN-resistant maize varieties and year-round cultivation of maize, allowing transmission via insect vectors, among others.


AATF activities have focused on supporting the production of MCMV-free seed in Ethiopia, Kenya, Rwanda, Tanzania and Uganda. With the trans-boundary nature of infection, it is crucial that countries adhere to a common management approach, including quality control in production of seeds.

MLN disease can result in yield loses of up to 100%, thus exacerbating food insecurity and affecting grain trade. The disease has been registered as a threat to food security in Kenya and Uganda.

During 2017, key activities included monitoring the implementation of MCMV-free seed production checklists that were produced in 2016. The project also carried out follow-up activities to assist breeders, seed companies and seed out-growers to implement the checklists. This involved on-farm visits to 66 seed companies across Ethiopia, Kenya, Rwanda, Tanzania, and Uganda to document feedback on the implementation of the checklists, best agronomic practices for MLN management and control, MLN status in seed production fields as well as MLN disease history within the seed production fields.

The visits also included training for the seed companies on the use of rapid MLN diagnostic techniques for early detection of suspect crops.