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Publication Date
Tue, 13 Feb 2018, 16:41
Last Updated
Feb. 13, 2018, 4:41 p.m.
Report Number
Tanzania- United Republic of
Report Status
The disease can affect wide range of hosts in the graminacea family. MCMV does not infect dicotyledons, but has a broad experimental host range that includes at least 19 grass species (Bockelman et al. 1989). Some of the hosts of MCMV apart from maize include finger millet, sorghum, sugarcane, Napier grass, kikuyu grass (P. clandestinium)
Pest Status (old values from ISPM 8 -1998 )
  • Present: only in some areas
  • Present: subject to official control
Pest Status (ISPM 8 - 2021)
  • Present: not widely distributed and under official control
Geographical Distribution
Maize Lethal Necrosis Disease in Tanzania is restricted to the northern part of Tanzania in the regions of Arusha, Kilimanjaro, Manyara, Mwanza, Shinyanga, Mara and the District of Kondoa in Dodoma region. These areas are located between longitude 32 W and 38 W and latitude 2 S and 4 s

During a monitoring and evaluation for the Maize working group activities in Tanzania in August, 2012 a peculiar disease was noted in Mlangiri in Arusha District, Rotia and Mbulumbulu in Karatu District (M & E Report presented to the MWG on 12th Nov 2012). A task force as formed comprising of staff from CIMMYT Kenya and Tanzania Scientist to conduct a survey of the disease (by George Mahuku and Dan Makumbi of CIMMYT 2012). Maize leaf samples were collected from affected areas in Mwanza, Manyara and Arusha regions and after analysis tested serologically positive for MCMV and SCMV, confirming the presence of MLN in Tanzania. The disease ever since has also been seen in Kilimanjaro region during the short rain crop in 2012, in Shinyanga, Mara and Irrigation schemes of Kondoa in Northern part of Dodoma in 2013.

Maize plants are susceptible to MLN at all stages in their growth, from seedling to maturity. As with all viral in plants viruses causing Maize Lethal Necrosis can be transmitted mechanically through farming equipment's etc. The MLN causing viruses can also be transmitted by a carrier-known as a "vector" from plant to plant and field to field. MCMV is carried by thrips and beetles and SCMV by aphids. Transmission of MCMV and SCMV can also occur via seed and is normally very low. SCMV = plants 21/72,897(0.03%). MCMV = 17/42000 & 1/22,189 (0.04%, 0.005%) seeds. However, even a low rate of seed transmission is epidemiologically significant, as a virus may be introduced into new areas through seed. Also, in conjunction with secondary spread by insect vectors, low rates of seed transmission can translate into high numbers of infected plants resulting in epiphytotics (Maule and Wang 1996). There is a tendency for continual cultivation of maize without seasonal breaks due to maize the potential of the crop in food and economic gains and this exacerbate the spread of the disease.
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