CURBING THE SPREAD of maize lethal necrosis in Africa

When Maize Lethal Necrosis (MLN) was identified in Africa for the first time in 2011, scientists feared the worst. The disease can lead to up to 100% grain loss in farmers’ fields, with symptoms including premature plant death and unfilled, poorly formed maize cobs. However, rapid and coordinated action among public and private institutions across sub-Saharan Africa has helped contain the spread of the deadly disease, averting a potential food security disaster in the region.

Early sign of maize lethal necrosis infection, mottling of leaves. Photo: Jennifer Johnson.

Maize is the primary staple food for more than 300 million consumers in sub-Saharan Africa, each of whom eats more than 50 kilograms of the grain on average per year, making MLN a direct threat to food security across the continent. By 2014, the disease had been reported in much of eastern Africa, including the Democratic Republic of Congo, Ethiopia, Kenya, Rwanda, Tanzania and Uganda.

Timely and targeted interventions from the CGIAR Research Program on Maize (MAIZE), International Maize and Wheat Improvement Center (CIMMYT), and partners including national agricultural research institutions, governments, commercial seed companies, and global R4D partners have largely controlled the disease. Due to these efforts, MLN has not been reported to have spread to any new countries since 2014.

Countries with confimed cases of MLN in Eastern Africa. No new countries have reported the disease since 2014.

“The battle against such a devastating disease had to be coordinated on multiple fronts, with a multi-pronged approach,” explained B.M. Prasanna, director of the CGIAR Research Program on Maize.

“Among other actions, MAIZE lead center CIMMYT established a dedicated MLN screening facility in partnership with KALRO at Naivasha in 2013. This has enabled screening of more than 175,000 germplasm entries over the last six years and helped identify MLN resistant breeding lines and hybrids,” Prasanna said.

Yoseph Beyene, maize breeder, center, instructs visiting students on MLN identification at the MLN screening facility in Naivasha, Kenya. Photo: Jennifer Johnson.

CIMMYT has also set up an MLN Quarantine Facility in Mazowe, near Harare, Zimbabwe, in 2017, in partnership with the Plant Quarantine Institute of Zimbabwe, for safe introduction of MAIZE and CIMMYT maize germplasm from Kenya to Zimbabwe. This work has been crucial in ensuring that improved maize varieties can be developed for Southern Africa without risking the spread of MLN.

The creation of an MLN information portal and related community of practice have helped partners across Africa to unite effectively against the disease. MAIZE and CIMMYT have also provided capacity development for public and private partners on MLN virus diagnostics and production of MLN virus-free seed, besides disease surveys. These efforts have helped significantly to keep the disease from spreading through commercial seed.

MAIZE researchers Yoseph Beyene and Manje Gowda proudly show off the difference MLN tolerant maize varieties can make. The small, damaged cob on the left came from an MLN susceptible variety, while the two large, high yielding cobs on the right are from an MLN tolerant variety. Photo: Jennifer Johnson.

MAIZE partners in multiple countries have released as many as 18 MLN tolerant/resistant maize hybrids resulting from the screening efforts, giving hope to smallholder farmers who have faced the disease in their fields by improving their yields, food security and livelihoods.

Despite these advances, the fight against MLN is not yet over. MAIZE and partners will continue to work together to prevent any spread of the disease and to support farmers in countries that have been affected.

“The coordinated and rapid response to major diseases and insect pests affecting maize-based agri-food systems in Africa shows the power of cross-sector and cross-regional partnerships,” Prasanna said.

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