Incidence and Impact of Maize Lethal

Necrosis Disease in Tanzania

Presented to Regional Workshop on MLN Diagnostic and Management in Africa Held at Intercontinental Hotel

Nairobi - Kenya

12th - 14th May 2015

By

Kitenge, Yangole, Makoye,

Mbwana & Inviolata

Outline

Introduction

Disease identification survey

Survey report

Measures taken

Immediate

Long term

Way forward

1. Introduction

In 2012, farmers reported of unknown disease affecting maize in some areas of

Lake zone (Mwanza, Musoma and Shinyanga)

Central zone (Singida)

Northern zone - (Manyara- Babati, Mbulu and Simanjiro)

(Arusha- Karatu, longijave, Mlangarini and Arusha)

(Kilimanjaro – Moshi Mwanga

Therefore there was a need of conducting a disease identification survey

Maize lethal necrosis infestation in northern part of

Tanzania

Maize lethal necrosis infestation in lake zone part of Tanzania

2. Disease identification survey

Following reports of an unknown disease in Tanzania,CIMMYT was invited to become part of a task force toconfirm reports of a new maize disease that has beenspreading and causing major loses among farmers

The Task force was comprised of Drs. George Mahuku(Pathologist),and Dan Makumbi (Maize Breeder) ofCIMMYT, and Dr AnneWangai from Kenya AgriculturalResearch Institute.

The team was hosted by Mr. Ignath Rwiza from theLake Zone

Agricultural Research Institute (LZARI) in Mwanza, and

late Dr. Richard Ndondi from Suba-Agro Trading

Company (SATEC) in Arusha.

In about 4-day period, the team managed to visited 8 farmsin the Mwanza region and 4 farms in the Arusha region.

A total of 60 samples (30 from Arusha region and 30 from Mwanza region) were collected and these were analyzed for thepresence of the potyvirus- sugarcan mosaic virus (SCMV)

Out the 30 samples from Mwanza region, so far 9have beenanalyzed and 4 samples tested positive for MCMV

Some of the samples were analyzed using reverse

ranscriptase polymerase chain reaction Rt-PCRtechnique with potyvirus-specific primers

…Survey report

All samples from the Arusha region have been tested, and

2 samples were positive for MCMV, 8 samples for SCMV and

14 samples were positive for both MCMV and SCMV.

No virus was detected in samples collected from a very

young crop labeled field 13 in Arumeru district. Maize lethal

necrosis disease (MLND) or Corn lethal necrosis (CLN) is a

result of infection of maize plants by SCMV and MCMV.

The detection of both viruses, either alone or in combination

in the samples collected confirmed the presence of MLND in

Tanzania

…Survey report

Affected plants Affected plants

Karatu April, 2013 Nshara – Hai, April 2013

Disease Symptoms

Disease Symptoms in cont’d

Mlangalini - Arusha Mlangalini - Arusha

Measures taken

Immediate actions

Sensitization activities

Information sharing with stakeholders (emails, reports)

Training extension, politicians and other decision makers at

district , region and national levels though their respective

meetings

Interviews to researchers made by journalists and Press releases

Present papers to policy makers within & outside the zone -

Parliament

Through conducted field visits to districts in the zone

Production & distribution of extension materials (brochure,

posters)

Video documentation

Still pictures collections

Participants from Rombo, March 12, 2013

Participants from Same and Siha DCs,

March 15, 2013

Participants from Arusha and Mbulu DCs, April 23, 2013

Participants from Babati TC, May 3, 2013

Effort to combat the disease

Writing a proposal involving multidisciplinary

activities to contain the disease

Breeders

Agronomists

Pathologists

Extensionists

Social economists

Police makers

National efforts

Tested available material for resistant

Testing for new developed materials (for SARI, Uyole

and from local seed companies)

Collection of new gerplasm from various places for

screening

Use of chemicals

Seed treatment

Routine plant spraying with systemic insecticide

Disease transmission

MCMV SCMVThripsAphids and

leafhoppers

Interaction between the two Diseases

MLND

Several insects implicated as vectors in literature:

Thrips

Aphids

Leaf hoppers

Corn root earworm

Most commonly thrips (Frankliniellawilliamsi) associated with MCMV and aphids with SCMV.

Transmission is non-persistent for both MCMV and SCMV

Spread

Regional efforts

KARLO –CIMMYT – developed a regional MLN

screening facilities at KARLO Naivasha where we

send our new material for screening

CIMMYT develop, screen, multiply and distribute

elite material among partners for testing

This season we have more than 3000 entries

(inbredlines and testcrosses) for evaluation under

MLN hot spot areas

Regional efforts con’t…..

ASARECA has significantly contributed to

MLN struggle

Funded a regional (Seven countries) two

year project combating the disease

We assemble new materials to CIMMYT

for screening multiply and distribute

among participating countries for testing

Solutions (What farmers should do)

Use treated improved seed

Proper field management

Fertilizer application

Field sanitation

Early planting

Rouging if few plants are affected

Distraction of the whole field

Crop rotation

Reporting to their leaders

2m apart

Maize affected by MLNDAmigo at 1.2mg rate + Thunder

MLN- INFECTION AT 5-6 WEEK

Seed dressed treatment + Foliar

applied

Untreated treatment

0

10

20

30

40

50

60

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Treatments

Health Plants

Health cobs

The mean maize health plants and cobs harvested per plots at Ngaramtoni

Results

1. Poncho FS600 at 0.5mg/kernel and Amigo

FS275 at1.0mg /kernel seed treatment

equally adequately protected the crop from

MLND infection via control of the aphids and

Thrips vector ,

but for only about 2 weeks after germination.

This was confirmed from less vector counts and

disease incidence in that period.

Conclusion

2. Thunder OD 145 foliar spray treatment alone

commencing from the 2nd week after germination was

not very effective in the disease reduction,

although the vector control from that period was

significantly reduced.

This means that the vector had already infected the

plants meaning that this intervention was already too

late for the disease control.

3. Generally, seed dressing combined with foliar

sprays tested in this study are effective in reducing

MLN incidence at early stages of plant growth.

Long term &The way forward

Continue collecting new germplasm and screen for

the resistance

Development of new varieties using resistantparental materials

Release of resistant varieties

Maintain restriction of seed movement

KOBE Mode of Action

Two Distinct Procedures

Inducing Plant Resistance

Mechanisms

Affecting the

Pathogen itself

SAR ISR

Kobe 1.2SL vs MLND

Traditional MLND management Only by trying to

manage the vectors (Aphids, Thrips ….)

KOBE Faces not the vector but the cause itself

Actually forces the plant to resist the disease

Promotes the plant’s own resistance capacity

Leads to more vigorous & stronger plants

Reduces the yield loss due to the disease

Kobe 1.2 SL

Rheum officinale Bail

Originating from Asia

Family: Polygonaceae

Common Name:

Rhubarb

In chinese: yào yòng dà

huáng (Chinese: 药用大黄

Apreciations

Thanks to

Organizers

Donors

The End