In Kenya, MLND was first reported in September 2011, at lower elevations (1900 masl) in the Longisa Division of Bomet County, Southern Rift Valley of Kenya. Later the disease was noted in Bomet Central Division, spreading into the neighbouring Chepalungu and Narok South and North Districts and Naivasha. By April 2012, the disease was reported in altitudes up to 2100 MaSL and in various parts of the country. Currently the disease has been reported in all provinces in Kenya except North Eastern. Latest reports indicate the disease has been noted in Tanzania, Uganda, Rwanda and South Sudan.
A serious new disease of maize appeared in the farmers’ fields in eastern Africa in 2011. Called maize lethal necrosis (MLN; or corn lethal necrosis, CLN), it can devastate maize crops. The disease is difficult to control for two reasons:

  • It is caused by a combination of two viruses that are difficult to differentiate individually based on visual symptoms.
  • The insects that transmit the disease-causing viruses may be carried by wind over long distances.
    National and global research and extension organizations, laboratories, and seed companies are working together to control the spread of the disease and to develop and deploy disease-resistant maize varieties for the farmers as soon as possible.
  • Signs And Precautions

    MLN threatens to devastate maize production in the North Rift, Kenya’s grain basket, after farmers reported an unusual yellowing of their maize plants.

    The disease, which is caused by a combination of Sugarcane Mosaic Virus and Maize Chlorotic Mottle Virus, makes the maize plant to wither and wilt before maturity. Plants appear weak, start shrinking with leaves turning yellowish and eventually they fall off and dry.

    Maize Lethal Necrosis disease is spread through the air and farmers are advised to take these three immediate measures to contain further spread of the disease.

  • Destroy by burning any crop infected by the disease
  • Practice crop rotation for at least for two seasons by planting non-cereals such as potatoes, beans, onions as well as vegetables
  • Plant certified seed and avoid use of recycled seed
  • Farmers also need to apply manure, basal and top dressing fertilizers to strengthen the plants’ resistance to disease and pests.
  • How to identify the maize disease

  • At knee height, the upper maize leaves start yellowing and later on start drying turning brown from the mid-rib towards the leaf margins.
  • The drying progress to the lower maize leaves
  • The stem and the nodes turn brown.
  • In some cases the maize produces many shoots (excessive tillering)
  • At the beginning it is only the upper leaves that appear brown
  • Towards maturity the cobs shrink and do not put in any grains.
  • In some cases the maize plant appears stunted.
  • Sept 2011, First reports in the lower parts of Longisa division of Bomet District.
    February 2012, noted in Bomet Central division, spread to neighboring Chepalungu District, Narok North & South Districts, Naivasha

  • Issues
  • Identification of the problem
  • Panic
  • Blame game- Associated with particular seed varieties and companies, industry
  • Farmers advised not to use certified seed
  • April 2012, Disease spread into Sotik,, Koinon, Transmara, Rumuruti, Kisii, Bureti, Kericho, Mathira East, Imenti South and Embu.
    Field observations revealed that the disease is affecting all maize varieties grown in these regions,
    Reported yield loss in affected fields ranged from 30-100%

    he focus on the disease management is surveillance and research with an aim of mitigation and establishing a lasting solution on the disease. Measures in place include:

  • Surveillance & Phytosanitation (elimination of infected plants), crop rotation , vector control and;
  • Screening, testing & introduction of resistant varieties
  • A coordinated intervention by relevant agencies including NPPO (KEPHIS), Ministry of Agriculture, Pest Products Control Board (PCPB), and Research organizations, namely Kenya Agricultural Institute (KARI), International Maize and Wheat Improvement Center (CIMMYT), and International Center for Insect Ecology and Physiology (ICIPE), Institute of Tropical Agriculture (IITA), among others is already in place to address the MLND problem. Already research is ongoing to identify and release resistant/tolerant varieties. Research coordinated by KARI and CIMMYT in two sites Naivasha and Bomet has screened over 200 accessions/varieties at different sites including Bomet and Naivasha. Already promising varieties have been identified and are undergoing bulking before commercialization. These include WEI 101, also known as Tumaini 1
    Maize lethal necrosis disease (MLND) is a serious threat to maize production where it occurs. For instance, in Kansas, crop losses due to MLND have been estimated to be 50-90% (Niblett and Claflin, 1978; Uyemoto et al., 1980) depending on the variety of maize and the year. In Peru, losses in floury and sweet maize varieties due to Maize chlorotic mottle virus have been reported to average between 10 and 15%. In Kenya, in areas where MLND was very serious, farmers experienced extensive or complete crop loss (Wangai et al., 2012). The infected plants are frequently barren; the ears formed are small, deformed and set little or no seeds, drastically reducing the yield. The areas affected constitute major maize production acreage and given the recorded loss of up to 100%, it has become an important food security issue in Kenya.
    The impact of the disease can been felt in the whole maize value chain. To help control MLND, the maize seeds are dressed with an insecticide in addition to a fungicide seed dressing.

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