By Martha Wairimu Nyambura
Nairobi, Kenya – Sixty four – year- old Wambui Muhiu, meticulously moves the jembe (hoe) back and forth hitting hard against the black cotton soil in her small acre of land in rural Kenya,Muranga County. Her efforts reveal a cluster of worms to which the chickens watching nearby greedily devour. The long rains of March-May have started albeit in torrents. Besides her is a two kilogramme bag full of maize seeds for planting.
“Last season some portions of my maize crop grew to knee high, the leaves turned yellow and those that grew produced very little grain,” says Wambui. Indeed farmers in Kenya, Uganda and Tanzania last year recorded losses of about 50-100percent on their total maize yields following the outbreak of a new maize disease known as Maize Lethal Necrosis Disease –MLND.
“It’s discouraging for the farmers because when they plant they harvest nothing; people depend on maize for food and if a farmer doesn’t have enough to eat and surplus to sell they are affected ‘” says Mr.Kheri Kitenge a maize breeder from SELIAN Agriculture Research Institute in Arusha, Tanzania.
“The status of the disease up to now is terrifying we think if it persists like last year it will have a very big impact on maize production,” says Kitenge. Consequently food security in the East African region remains precarious as a large portion of maize is produced by farmers like Wambui who form part of the 70 percent subsistence farmers in the African continent that largely depend on maize for food and as a cash crop.
“We are encouraging farmers in this planting season to look to other crops such as sweet potatoes, cassava and beans as an alternative to maize as researchers in the East African region collaborate to find a resistant variety to MLND,” says Dr.Ephraim Mukisira the director of the Kenya Agricultural Research Institute-KARI.
However Wambui is reluctant to make a complete shift to cassava which she says fetches very little in the local market compared to her maize crop. “I have decided to change seed brands this time, to see if I get a better harvest,” she quips, despite paying an extra 200 shillings to acquire the new batch of maize seeds.
MLND researchers in the region say chances that the disease is seed borne are minimal. The virus an obligate only thrives in a living organism says Dr. Ann Wangai chief research officer at KARI.
The disease is as a result of a combination of two viruses the Sugarcane Mosaic Virus (SCMV) which affects many cereals and Maize Chlorotic Mortle Virus (MCMoV) that combine to gives rise to MLND explains Dr. Wangai.
It is spread by vectors such as thrips and maize beetles in a non-persistent manner. This means that any insect that feeds on the sap of an infected maize crop even if it was just probing to see if the plant is a palatable host to feed on; it carries the virus and if it probes into another plant which might be maize it transmits the disease, she explains.
Maize crops infected by MLND are dwarfed in size; have an irregular yellow pattern forming on the leaves with low grain content. Although MLND affects maize crops we cannot rule out the possibility that it may affect other cereals, adds Dr.Wangai.
MLND was first reported in Kenya in late 2011 in Bomet, Rift valley region considered the country’s bread basket and by 2012 it had spread as afar as the Mt.Kenya region in Embu and Meru.
In Uganda it was seen in October at the border district of Busia and Tororo and since then we have had reports in the neighboring districts of Mbaale and Igaanga all in Eastern Uganda says Dr.Godfrey Asea a maize breeder from the National Crops Resources Research Institute in Kampala, Uganda.
Whereas Tanzania sighted MLND in its backyard in 2010 the disease was not spotted in 2011 but reoccurred again in 2012 in areas bordering Kenya on the Coastal zone such as Mwanza, next to Lake Victoria and Arusha that borders Mt.Kilimanjaro eventually the disease spread to other far flung areas says Mr.Kitenge.
“There are many unknowns in regards to the spread of this disease but the different planting times are a factor. In Uganda, farmers that planted early experienced less losses compared to those who planted late, says Dr.Asea.
The vector prefers succulent leaves of younger plants as they have more sap to suck on compared to those of an older plant, so it moves from a mature field to a younger one, he explained.
Unfavourable weather patterns could explain the time jump in the occurrence of MLND in Tanzania, says Mr.Kitenge.
The outbreak and ensuing quick spread of MLND put the spotlight on Kenya’s disease monitoring and response channels with researchers and plant health inspectorates shifting blame.
To curb the spread of the disease the ministry of Agriculture in Tanzania imposed a quarantine on Kenyan seeds in 2012 with the ban limited to research materials from Kenya.
Uganda formed a national task force to address the disease by doing awareness campaigns and training extension officers on management of the maize disease.
We have had to do more on disease surveillance in the country, explained Dr. Mukhisira, we set up two experimental sites in Bomet and Sunripe farm in Naivasha where research is currently underway to find a maize breed that is resistant to the disease.
We are using artificial inoculation to test resistance for the disease as it is easier to determine the amount to apply says Dr.Wangai who is leading the research at the Sunripe farm in Naivasha.
The varieties under study are the most popular commercial hybrids from KARI and the International Maize and Wheat Improvement Centre –CIMMYT.
We are working overtime to ensure that once a resistant variety is found they distribute it to seed companies. Usually the release of new seed varieties in Kenya is done by KEPHIS after a two year testing period explains Scientist and maize breeder Dan Makumbi of CIMMYT.
As collaboration efforts continue among researchers maize farmers in the three countries are advised to intercrop maize with other crops, practice crop rotation as continuous maize in the field perpetuates the disease and diversify to other crops.