Maize Lethal Necrosis Disease (MLND)

An Overview of the disease affecting

maize

TRAINING WORKSHOP ON MLN DIAGNOSIS AND MANAGEMENT

17th -19th MARCH 2015

Dr Anne Wangai

Contents

•Causal agents

•Global history

•Symptoms

•Disease occurrence & effects

MLND

Causal agents

Maize

chlorotic

mottle virus

(MCMV)

Sugarcane

mosaic virus (SCMV) or other

Potyviruses

What is causing the maize disease?

Sugarcane mosaic virus

Family: Potyviridae

Genus: Potyvirus

Species: Sugarcane

mosaic virus

Acronym: SCMV

Maize chlorotic mottle virus-(MCMV)

Family:

Tombusviridae

Genus:

Machlomovirus

Species: Maize

chlorotic mottle

virus

Acronym: MCMV

MLN disease development Environmental

conditions: Favouring vectors

and pathogen

Virus: Either single or

compound

Germplasm:

Susceptible/Resistant

Vectors/seed/ other

transmission

RATE OF DISEASE

DEVELOPMENT

Disease Outbreak

•SCMV described in Eastern Africa in 1930’s

•MCMV first detected in Kenya in 2012.

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

?????? ?

Introduction: Trend of global occurrence of MLND (CLND)

•Mild mosaic,

•Systemic chlorotic leaf mottling

•Severe stunting,

•Leaf necrosis,

•Premature plant death,

•Shortened male inflorescences with few spikes,

•Shortened, malformed, partially filled ears

•Mixtures of MCMV with any of several

potyviruses also causes necrosis, stunting and

death.

Typical symptoms of MCMV

FIELD CROP INFECTED BY MLND

Maize leaves: MLND VS HEALTHY

Severe chlorotic mottle on the leaves

Chlorotic mottle on leaves –parallel to the mid vein

Chlorotic stripes and mottle on leaves

Bleaching of leaf margins and mottle

Broad chlorotic banding on leaves

‘Dead Heart’ symptoms

Ultimate drying up

Poor or no grain filling

Husks dry prematurely, no grain

Losses along Value chain

Food and economic security threatened

Losses for seed producers (for both growers and seed companies)

Millers (both in quality and quantity)

Transporters (reduced volume of business)

Storage facilities (dormant capacity)

Middlemen (loss of business volumes)

Host range

WAY FORWARD- What We Do not Know

• MLND-Where to Next?

• MCMV resistance in maize germplasm

• MCMV variability

• Extent seed transmission contribute to the introduction/ spread/ sustaining disease in the region

• Alternative hosts (reservoirs) for MCMV/SCMV.

• Role of Maize streak virus and other pathogens/stresses factors in MLN epidemic.

• Full range of other viruses present in the maize-growing systems

• MLND contribution to elevated Mycotoxins in maize grainRole of maize thrips, beetles, other insects/nematodes in MLN outbreak.

• The extent of MCMV transmission through Soil/water/plant

debris/plant to plant transmission?

PARTNER INSTITUTIONS COLLABORATORS

MoAL &F

KARI

KEPHIS

PCPB

UoN

CIMMYT

icipe

BecA

STAK

CGA

AAK

OARDC- Ohio State

University, USA

University of Minnesota,

USA

CABI

Food and Environment

Research Agency (FERA), UK

Cambridge University, UK

Institutions in MLND research activities

Government

Organizations

International

Research

Organizations

Private

Organizations

Acknowledgement

•Director KALRO

•KAPAP

•MLND Technical Team

•MoA&L

•CIMMYT