MLN's incidence and impacts in Kenya, presented at the International Conference on “MLN Diagnostics and Management in Africa,” organized by AGRA (Alliance for Green Revolution in Africa) and CIMMYT, 12-14 May, 2015

1. Maize Lethal Necrosis Disease (MLND) in
Kenya
Incidence and Impacts
WORKSHOP ON “MLN DIAGNOSTICS AND MANAGEMENT IN AFRICA”
Intercontinental Hotel, Nairobi - May 12-14, 2015
DR. ANNE WANGAI

2. CONTENTS
Introduction
Some preliminary observations
Way forward

3. Introduction: Disease Outbreak
Farmers in Bomet called it, ‘Koroito’
Vernacular name for ‘ a plague’
 A sudden phenomenon that could not be
explained, unknown causes,
 Resulting in a devastating effect to the community.

4. …..Introduction - Genesis of the Disease
September 2011, disease first reported in the lower parts of
Longisa division of Bomet District.
February 2012, noted in Bomet Central division, spreading
into neighbouring Chepalungu District, Narok North & South
Districts, Naivasha
July 2012, Disease confirmed in most areas in South Rift,
Central, Eastern and North Rift regions
All commercial maize varieties including farmers’ local
varieties in these regions were susceptible
Yield loss ranged between 30-100%

5. MLN Predicted Hot spots in Africa (ASARECA, 2014)

6. Country Year Reference
Peru 1973 Castillo and Hebertt (1974)
USA 1976 Niblett and Cafflin (1976)
Argentina 1982 Teyssandier et al. (1982)
Mexico 1987 Delgadillo and Gaytan (1987)
Brazil 1983 Cited in Uyemoto (1983)
Thailand 1983 Cited in Uyemoto (1983)
China 2011 Xie et al. (2011)
Kenya 2012 Wangai et al. (2012
Tanzania 2012 CIMMYT TF Rept to Ministry of Agriculture, Tanzania
Uganda 2012 G. Asea, Workshop (Nairobi; Feb 12-13, 2013)
Rwanda 2013 C. Ngabiyasonga, MLN Training Workshop (Nairobi; 2013)
DRC 2014 Kumar , FAO Regional Meeting, Nairobi, 2014
Ethiopia 2014 CIMMYT T-Force Rept to Ministry of Agriculture, Ethiopia
Where
?
…..Introduction: Trend of global occurrence of MLND (CLND)

7. …..Introduction: Perceived impact of MLND
 Food Security
 Farm income
 Food shortage
 Period to receive
effective, affordable and
sustainable control
measures
 Difficulty of shifting from
their dietary preference of
maize
=======================
Seed production
Trade implication
Regional/International
threat

8. Some preliminary observations

9. POST HARVEST ISSUES:
Deterioration of grain Quality

10. (2014)

11. 45%
1%0%
54%
MERU
67%
0%
4%
29%
MURANGA
72%0%
0%
28%
KIAMBU
MCMV
SCMV
BOTH
NONE
CENTRAL

12. 38%
2%
31%
29%
NAKURU RIFT
40%
12%
43%
5%
BARINGO
46%
1%19%
34%
Bomet
MCMV
SCMV
BOTH
NONE

13. 0
10
20
30
40
50
60
70
80
%YIELD LOSS DUETO MLND -2014
% YIELD LOSS DUE TO
MLND

14. Next Generation sequencing ( Mwathi et al. 2015 )
Viruses identified so far:
Identified Virus Acronym
Sugarcane Mosaic virus SCMV
Maize Chlorotic Mottle virus MCMV
Maize Streak Virus MSV
Maize Dwarf mosaic virus MDMV
Barley yellow dwarf virus BYDV (Luteovirus)
What else ??????

15. MCMV transmission (Nyvall 1999)
•Mechanical
•Insects
Corn thrips
Corn flea beetle
Cereal leaf beetle
Corn rootworm
• Seed transmission rates – very low
–MCMV = 17/42,000 plants (0.04%)
–MDMV(SCMV) = 21/72,897 plants (0.03%)

16. Effect of agronomic practices on disease spread and
severity (Amata et al. 2015)
Data on MLND incidences, severities and yield collected in
Naivasha, Bomet and Narok counties from trials on effect of
 fertilizers,
spacing
rouging and
intercropping.
Treatments did not affect the incidences and severities of MLN.
Intercropping maize with either beans or pyrethrum did not
affect incidences and severities of MLN

17. Role of plant debris and soil in survival and spread of viruses
causing MLND (Odula et al. 2015)
Percentages of MLND infected plants noted:
0
10
20
30
40
50
60
70
80
Leaves Stem Roots Infected soil whole plant Sterie soil
%infection
%infection

18. Other pathogens & nematodes associated with MLND
causing virus (Kinyua et al.2015)
Fungi commonly isolated
were:
Fusarium sp.,
Phyllachora maydis,
Penicillium sp.,
Diplodia sp. &
Colletotrichum sp.
Nematodes commonly
extracted were:
Helicotylenchus,
 Rotylenchulus,
Pratylenchus,
Meloidogyne,
 Hoplolaimus &
Tylenchus

19. Susceptible Susceptible
/resistant
Resistant
Zea mays Triticum sppHordeum vulgare L.
Eleusine coracana
Sorghum bicolor
Oryza sativa
Pennisetum purpureum
Chloris gayana
Pennisetum cladestinum
Cynodon dactylon
Cyperus rotundus
Chloris rexburghiana
Enteropogon macrostachyus
Eragrostis superb
Cenchrus ciliaris
Host range
(MCMV)
(Odula et al.2015)

20. Vectors of viruses causing MLND, their host range
and management options (Nyasani , Kasina et al. 2015)
Competences of 5 potential vectors for transmitting either
MCMV or SCMV have been determined
Three (3) potential vectors of MCMV have been identified.
One (1) potential vectors of SCMV has been identified.
Six (6) host plants of MCMV/SCMV have been identified.
Three (3) natural enemies of thrips have been identified.

21. Distriburion maps of potential vectors of viruses
causing MLND
Beetles Aphids
LeafhoppersStemborersThrips
Spatial distribution of
potential vectors of
Maize chlorotic mottle
virus and Sugarcane
mosaic virus in Kenya
(Nyasani et al. 2015)

22. Evaluation of pesticide control options for MLND
(Kinyua, Kasina,Ngaruiyaet al. 2015).
Trial involving 8 foliar products:
Carbosulfan,
Acephate,
Thiocyclam,
Chloropyrifos,
Imidachloprid,
Acetamiprid,
dimethoate and
thiamethoxam
Seed treatment pesticide
technologies for the control of
MLND. 3 seed treatment products
 carbosulfan,
thiamethoxam and
clothianidin).

23. Way forward:
SCMV and MCMV were prevalent: Variability and distribution
need to be established
MCMV is THE major virus of concern: Other viruses/factors
involved in MLN expression to be identified.
Seed transmission is playing an important role in spreading
MCMV: Seed transmission and contamination to be eliminated
Soil and plant debris play a role in retaining virus: Farm
practices to be identified to prevent re-introduction and
sustaining of MCMV
Longterm solution: Resistant germplasm deployed

24. Acknowledgement

25. Acknowledgement
Director General, KALRO
KAPAP
MLND Collaboration Team
MoAL&F
CIMMYT
AGRA