Visual inspection to manage bacterial wilt in Sub-Saharan Africa: Improving seed quality and...

Visual inspection to manage bacterial wilt in Sub-Saharan Africa:

Improving seed quality and impacting smallholder farmers

Parker, ML, Mugo, J, Gutarra, L, Orrego, R and Schulte-Geldermann, E.

European Association of Potato Research Triennial Conference, Brussels July 7-11, 2014

Bacterial Wilt (BW) major (principal) constraint to potato production

BW = Ralstonia solanacearum

Massive host range (> 200 plant species)

Survivor

Impact of bacterial wilt on smallholder farmers

Major cause of poor seed quality and consequently, low yields

(8-12 t/ha)

Spread seed tubers contaminants irrigation/water run-off

NO host resistance

NO chemical control

Management relies on: clean seed sound crop rotation

Management

Unavailable

Quality (formal) seed difficult to access

Expensive

Informal seed system dominates in SSA farmer-saved seed unmarketable tubers

Main culprit = SEED

Prevalence

Wide spread in SSA from low to high altitudes

Region Incidence(%)

1500 -2200 m

> 2201 m Region Incidence(%)

1500 -2200 m

> 2201 m

Aberdares 0 6 5 Mau 0 1 4

1-9 1 4 complex 1-9 5 3

10-20 2 5 10-20 2 2

above 20 0 6 above 20 1 1

Elgon 0 4 6 Mt Kenya 0 6 3

1-9 2 2 1-9 2 0

10-20 3 4 10-20 3 1

above 20 1 7 above 20 4 1

BW was observed on 121 farms of a total 156 farms (78%)

Improving access to quality seed

Certification regulations exist, practice is minimal In Kenya

quantities of certified (formal) seed supply approximately 2% of demand

available at a few locations across the country Costly

certify seed lots purchase

tissue culture/minitubers/first field generations

onward, localised multiplication

decentralised multipliers

Improving access to quality seed

Formal certification

Quality Declared Planting Material

QDPM

VISUAL INSPECTION by recognised committees

Removing infected plants from seed multiplication plots (negative selection)

GAP - particularly crop rotation, alternative host management and field hygiene

QDPM is promoted among decentralised multipliers

Thereby increasing geographic and economic accessibility to quality seed

Local trade only

QDPM: an alternative approach to assess seed health

Yie

ld t

/ha

35.0

25.0

8.0

05

10

1520

25

30

Improvedon-station

Improvedon-farm

National Average

QDPM

Ethiopia


VISUAL INSPECTION

Farm-saved seed

Marking and saving tubers from the healthiest plants in a crop for the following season’s seed

Positive selection

BW

in

cid

ence

(%

) 45

20

FSS PSS CS

Kakuhenzire et al., 2013

Positive selection

Another main culprit = poor rotation

Potato key (only!) cash and food security crop for farmers in mid to highland regions

Season after season, farmers plant potato on same site

Lower altitudes, farmers crop numerous solanaceous crops

Improving crop rotation

Region CropCFU / g soil

Before planting After planting

Huanucalla Potato 188 11248

Onion 836 401

Chinchinga Potato 50 426

Onion 38 17

In each region, onion reduced CFU by ~ 50%

Genotype Biovar1 Biovar 2A Biovar 2T Biovar 3204 364

Wilt Latent Wilt Latent Wilt Latent Wilt Latent Wilt Latent

391919.3 0 0 67 0 7 0 0 0 0 13 391930.1 0 27 47 0 20 7 0 0 0 7 392278.19 0 33 73 0 20 0 0 20 0 0 394895.7 0 0 7 0 0 0 0 0 0 7 394903.5 0 7 20 33 13 7 0 0 0 0 394904.2 0 0 27 27 13 20 0 0 0 7 394904.9 0 0 47 0 20 0 0 20 0 0 394905.8 0 0 13 33 0 7 0 0 0 7 393909.2 0 20 87 0 60 0 0 13 0 0 395438.1 0 7 33 0 13 13 0 0 0 011049.0 7 7 33 0 0 0 0 0 0 60Revolución 0 27 87 13 60 0 0 60 0 27

No visible wilt and no latent infection = NO THREAT

Can latent infection threaten effectiveness of QDPM?


Genotype Biovar1 Biovar 2A Biovar 2T Biovar 3

204 364


391919.3 0 0 67 0 7 0 0 0 0 13 391930.1 0 27 47 0 20 7 0 0 0 7 392278.19 0 33 73 0 20 0 0 20 0 0 394895.7 0 0 7 0 0 0 0 0 0 7 394903.5 0 7 20 33 13 7 0 0 0 0 394904.2 0 0 27 27 13 20 0 0 0 7 394904.9 0 0 47 0 20 0 0 20 0 0 394905.8 0 0 13 33 0 7 0 0 0 7 393909.2 0 20 87 0 60 0 0 13 0 0 395438.1 0 7 33 0 13 13 0 0 0 011049.0 7 7 33 0 0 0 0 0 0 60Revolución 0 27 87 13 60 0 0 60 0 27

Very visible wilt and no latent infection = NO THREAT

Can latent infection threaten effectiveness of QDPM? Genotype Biovar1 Biovar 2A Biovar 2T Biovar 3

204 364


391919.3 0 0 67 0 7 0 0 0 0 13 391930.1 0 27 47 0 20 7 0 0 0 7 392278.19 0 33 73 0 20 0 0 20 0 0 394895.7 0 0 7 0 0 0 0 0 0 7 394903.5 0 7 20 33 13 7 0 0 0 0 394904.2 0 0 27 27 13 20 0 0 0 7 394904.9 0 0 47 0 20 0 0 20 0 0 394905.8 0 0 13 33 0 7 0 0 0 7 393909.2 0 20 87 0 60 0 0 13 0 0 395438.1 0 7 33 0 13 13 0 0 0 011049.0 7 7 33 0 0 0 0 0 0 60Revolución 0 27 87 13 60 0 0 60 0 27

No visible wilt and latent infection = THREAT


Genotype Biovar1 Biovar 2A Biovar 2T Biovar 3

204 364


391919.3 0 0 67 0 7 0 0 0 0 13 391930.1 0 27 47 0 20 7 0 0 0 7 392278.19 0 33 73 0 20 0 0 20 0 0 394895.7 0 0 7 0 0 0 0 0 0 7 394903.5 0 7 20 33 13 7 0 0 0 0 394904.2 0 0 27 27 13 20 0 0 0 7 394904.9 0 0 47 0 20 0 0 20 0 0 394905.8 0 0 13 33 0 7 0 0 0 7 393909.2 0 20 87 0 60 0 0 13 0 0 395438.1 0 7 33 0 13 13 0 0 0 011049.0 7 7 33 0 0 0 0 0 0 60Revolución 0 27 87 13 60 0 0 60 0 27

Visible wilt and latent infection = THREAT

Improving effectiveness of visible inspection

Knowledge on Rs isolates

Simple tools for field based diagnostics

Further validation of rotation (onion) to reduce Rs populations in soil

Understand infection gradient from an infected source

Asante Merci

Murakoze Thank you

Gracias Obrigado

አመሰግናለ

ሁ

Zikomo

Dank u wel

Summary

QDPM is an effective and accessible approach for small-scale seed multipliers to maintain seed quality

Positive selection provides farmers a way to save seed on farm while maintaining quality

Although promising, crop rotation patterns require further validation to assess effect on BW

Attention to Rs isolates and latent infection

CS

20

40Tu

ber

yie

ld (

t h

a-1)

FSPSSQDPMBasic

Kakuhenzire et al., 2013


Visual inspection to manage bacterial wilt in Sub-Saharan Africa: Improving seed quality and...

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