What causes MLN?

MLN is typically caused by the synergistic interaction between maize chlorotic mottle virus (MCMV) and any cereal Potyvirus e.g, sugar cane mosaic virus (SCMV) or maize dwarf mosaic virus (MDMV).

How is MLN transmitted?

MLN causing viruses can be transmitted by a range of insect vectors; including thrips and chrysomelid beetles for MCMV and predominantly aphid species for potyviruses. Seed borne transmission or transmission via seed contamination also occurs – seed is now thought to be more more important in transmitting MCMV in Africa than previous studies had indicated. 

Have MLN resistant varieties been developed?

Yes. Five first generation tolerant MLN hybrids have been released in East Africa. Two in Uganda, two in Kenya and one in Tanzania. A further 15 second-generation CIMMYT-derived MLN resistant hybrids are presently under NPTs in Kenya, Tanzania and Uganda.  These have much greater resistance levels compared to the first generation hybrids. 

Is MLN harmful to humans or livestock?

You can feed the leaves to livestock, BUT this is a way that could spread the disease to other fields or areas.

Do not allow humans or animals to eat infected ears or grains, which may contain secondary fungal infections and harmful mycotoxins. Burn infected ears and grains.

How can I control MLN?

See the Control and Management page for detailed advice

If I see symptoms of MLN in maize fields who should I contact?

If you suspect MLN, contact Ministry of Agriculture officials, national plant protection agency staff or agricultural research staff.

How can breeding lines be screened against MLN?

KALRO and CIMMYT have established a dedicated MLN screening facility at KALRO Naivasha Research Center, Kenya. This facility is available to partners (both public and private sector) and germplasm can be screened against MLN under controlled artifical inoculation.

What is the current status of MLN? In which countries is it now present?

MLN has been confirmed in 6 East African countries. It was first detected in Kenya in 2011. It has subsequently spread to Uganda (2012), Tanzania (2012), DR Congo (2013), Rwanda (2013) and Ethiopia (2014). Field reports have also come from South Sudan (2013) and Burundi (2013), but no confirmation has been obtained (No publication or confirmed laboratory results). No reports of MLN have been received from Southern or West Africa.

For more details contact:


Dr. Suresh, L.M.  | Maize Pathologist – Sub Saharan Africa, Global Maize Program &

Manager – MLN Screening facility

International Maize and Wheat Improvement Center (CIMMYT)

World Agroforestry Centre (ICRAF), United Nations Avenue, Gigiri. P.O.Box 1041–00621, Nairobi, Kenya

tel: +254 (20) 7224069  skype: suresh.lm   cel: +254 702392664 Tweeter : _lmsuresh