daniel chigunweFildah Gwati
FOLLOWING the detection of the maize lethal necrosis (MLN) viral disease in some parts of Africa, CIMMYT has taken the initiative to train local experts on ways of combating the spread of the disease in Zimbabwe, as efforts to achieve food security gather tempo.
In an X (formerly twitter) post, CIMMYT hinted that it was on the frontlines empowering local experts to combat maize lethal necrosis saying the vital training sessions were key to protecting the nation’s staple crop from this serious threat and safeguard the country’s future food situation.
Said CIMMYT: “Maize lethal necrosis (MLN) is a viral disease caused by the synergistic interaction between maize chlorotic mottle virus (MCMV) and any cereal potyvirus for example sugar cane mosaic virus (SCMV) or maize dwarf mosaic virus (MDMV). The 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 important in transmitting MCMV in Africa than previous studies had indicated.”
CIMMYT, however, revealed that there were no reports of MLN that had been received from Southern or West Africa.
The viral disease has, in fact, been confirmed in six East African countries. It was first detected in Kenya in 2011 and 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).
CIMMYT identified several preventive measures that can significantly reduce the impact of the disease on maize production and food security.
MLN does not occur on crops other than maize, hence the need for farmers to avoid growing maize on the same land continuously but practise rotation through planting different crops each season. They must also not plant a new maize crop near an infected field while wind-blown insect vectors can also transmit the disease from an infected field to a new crop.
Farmers must plant maize at the onset of the main rainy season, rather than during the short rain season because this creates a break between maize crops and interrupts the disease cycle. They also need to weed regularly to eliminate alternate hosts for insect vectors and use maize varieties that are resistant to MLN.
In the event that farmers discover MLN in their fields, they must take urgent action to contain it.
“Diseased plants should be promptly removed from the fields and the leaves can be used as feed for livestock. It is crucial to prevent humans and animals from consuming infected ears or grains, as they may contain secondary fungal infections and harmful mycotoxins. The recommended course of action is to burn the infected ears and grains to prevent further spreading,” added CIMMYT.
Online Reporter