This presentation was made at the Refresher Course on Potato Seed Production organized by Wageningen UR at the Kenya Plant Health Inspectorate Service (KEPHIS) in Nairobi, Kenya on the 25th November to the 6th December 2013.

1. Dr. Ir. Dieudonné Harahagazwe
International Potato Center, CIP
CONTROL OF BACTERIAL WILT IN EASTERN,
CENTRAL AND SOUTHERN AFRICA:
Successful Strategies

2. Bacterial Wilt in SSA
= Ennemy No. 1 of Seed Production
Systems
Reduction of field BW infection from 60% to
0.7% (Berrios and Rubirigi, 1993)

3. Disease Triangle = Basis of Control Strategies
Pathogen
Host
Environment

4. Strategy 1
Clean Seed
• Formal Seed Systems
• Informal Seed Systems

5. Formal Seed Production Systems
• In vitro plantlet multiplication
• Mini-tuber production
– Conventional technique (sterilized substrate)
– Rapid multiplication techniques (cuttings)
– Aeroponic technique (Kenya, Malawi,
Mozambique, Rwanda)
– Sand hydroponic (Tanzania, Mozambique,
Rwanda)

6. • Field Multiplication:
– Pre-basic Seed Production
– Basic Seed Production
– Certified Seed Production
• Case Study: Burundi Seed Scheme

7. Tissue Culture Labs
Lichinga, Mozambique (2012) Ruhengeri, Rwanda (2006)
Tigoni, Kenya (2011)
Gisozi, Burundi (2012)

8. Conventional mini tuber
production
Ruhengeri, Rwanda (2006) Mulungu, DR Congo (2013)

9. Sterilization of Substrate
Ruhengeri, Rwanda (2006)
Gisozi, Burundi (2010)
Sussundenga, Mozambique (2013)

10. Aeroponic Seed Production
Tigoni, Kenya (2010)

11. Malawi, 2010

12. Sand Hydroponic Production
Maputo, Mozambique (2013)
Source: Armando Chilenge

13. Cold storage (Lichinga, Mozambique)

14. Quality Assurance and Control
Official Standards
(variability across countries)
Field Inspection
Lab techniques
(Latent infection mainly)
Gisozi, Burundi (2004)

15. Informal Seed Production
Self Supply of Clean Seed by
small-scale farmers:
–Small plot techniques
–Diffused Light Storage (DLS)

16. Small Plot Technique
• Gusubizako ivu
• Gutera: 20 cm x 20 cm
• Gukangaza no gufurira
• Gupompa
• Gusoroma
1,6 m
9
m
Buyengero, Burundi (2007)

17. Buyengero, Burundi (2007)

18. Season 1
Season 2
Season 3
Season 4
SSP 1
SSP 2
SSP 3
SSP 4
Ware Plot 1
Ware Plot 2
Ware Plot 3
Market
Market
Market
Sequence of Seed and ware Plots

19. Quality Seed Means Approriate Storage
Angonia, Mozambique (2012) Tsangano, Mozambique (2010)
Promotion of low cost DLS for farmers

20. Farmers’ DLS at Malomo EPA in Ntchisi (Nov. 2009)
Farmers’ DLS in Mchinji (Nov. 2009)
A farmer inside his DLS in Mchinji, 2011
Examples of DLS in Malawi (Source:
P. Demo)

21. Farmer’s Improved DLS
Rotanda, Mozambique (2012)

22. Strategy 2
Pathogen Free Land/Soil
Example of
• Western Kenya
• Central Kenya
• Mozambique

23. Bacterial Wilt Incidence in Western Kenya (Trials 2013)
Genotype
393079.4
SH
ER
EKEA396027.2396036.2398098.7398180.3398180.9398190.4398180.2
398192.41
398193.65
398208.29
398208.505
398180.292
398208.704
BacterialWilt(%)
0
20
40
60
80
100
120
Itando
Mudungu
Ivojo

24. On-Farm Trials in Embu District, Kenya
(Linus, M., Muriithi, M. and Irungu)
Period: 1999 – 2000
Seed used: Certified Seed Tubers of Asante
Surprising findings: 3.6 % (1999) and 3.2 %
(2000) of Bacterial Wilt Incidence:
“However, the farmers were advised to choose an area where
potatoes or other related crops like tomatoes had not been
planted for 3 years as precaution against possible source of
BW infection” (Linus et al., 2004)

25. Bacterial Wilt in Vanduzi
farm, Mozambique (2012)

26. Strategy 3
Appropriate Crop Rotation
Systems
• Case study of Kabale (Uganda)
• Case Study of kajondi (Burundi)

27. Rotation Experiments in Kabale, Uganda
(Lemaga, B., Kanzikwera, R., Kakuhenzire, R., Hakiza, J.J. and Maniz, G.)
Period: 1995B – 1999A
Site: Kachwekano (2200 masl)
Variety: Victoria (Asante)
Experiment 1 (one-season rotation):
maize, wheat, beans, onions, peas, cabbage,
sweetpotato, millet, carrots
Experiment 2 (two-season rotation):
Beans – wheat/Beans – maize/Wheat –
maize/Beans – beans/Maize – maize/Wheat –
wheat

28. Key findings (Lemaga et al., 2001a)
One-season Rotation:
Maize and wheat reduced the BWI by around 18%
and significantly increased tuber yields
Beans alone not advised as it might carry the
bacterium
Lowest incidences with finger millet and
sweetpotato but with low yields as they are
reported to be heavy feeders (competition – need
to fertilize)

29. Two-season rotation:
All rotations reduced BWI but planting 2
different crops was superior to planting the
same crop in 2 consecutive seasons
Best rotations:
Potatoes – beans – maize – potatoes (81 % to
21.9%)
Potatoes – wheat – maize - potatoes

30. Kajondi Basic Seed Farm (Burundi)
• 300 ha arable land
• Around 25 ha of
clean basic
seed/season
• Rainfall: ca. 1400
mm/year
• Tmean: ca. 17°C
Source: Google Earth

31. Rotation Plan in Kajondi
Hill Block
Area
(ha)
98 B 99 A 99 B 00A 00B 01A 01B 02A 02B 03A 03B 04A 04B
I
1 25
2 22
3 25
III
1 20
2 26
3 20
V
1 20
2 22
Potato Maize Fallow Buckweat
Wheat
Source: Bizoza, 2001

32. Some results
Year
1993 1994 1995 1996 1997 1998 1999 2000 2001
BacterialWilt(%)
0.0
0.1
0.2
0.3
0.4
Production(x1000t)
150
200
250
300
350
400
Data from Bizoza, 2001

33. Strategy 4
Negative Selection (Rogueing)

34. Field detection (Rotanda, Mozambique)

35. Wilted
Plant
G1 Field
G2 Field

36. Rogueing by farmers
Example of Burundi Example of Mozambique

37. Strategy 5
Other Agronomic Practices

38. Geospatial distribution
Toposequence of
seed plots (run-
off)
Logical altitudinal
localization of
seed centres per
seed grade
Mugamba, Burundi

39. Case study: Lulimile production in Mozambique
40 kg of mini tubers
1 t of G1
Tsangano,
2011
6 t of G2
Ntengo umodzi, 2012
0.6 ha of G2
Ntengo umodzi, 2012

40. Liming
The incidence of BW
is exacerbated
under low pH
Literature cited by Lemaga
et. al, 2001b and Linus et
al. 2004

41. Soil Fertilizers
Organic Manure
(Mparambo, Burundi)
Inorganic Fertilizers
(Rotanda, Mozambique)
Soil Amendments on BWI (Lemaga et al., 2001b):
Best results when organic and inorganic fertilizers combined
Presence of K in any combination of amendments important for both BW reduction
and yield increases
Sesbania gave best results compared to other green manures

42. Key Message – Integrated Approach
1) Clean Seed
2) Pathogen Free Soil/Land
3) Appropriate Rotation Systems
4) Negative selection
5) Quality Control (Latent Infection/ELISA-
Test)
6) Other Agronomic Practices (soil
amendments, Volunteers, altitude of seed
centers, etc…)

43. References
• Linus, M., Muriithi, M. and Irungu, J.W. 2004. Effect of integrated use of inorganic
fertilizer and organic manures on Bacterial Wilt incidence (BWI) and tuber yield in
potato production systems on hill slopes of Central Kenya. Journal of mountain
Science, Vol. 1. (1): 81-88.
• Lemaga, B., Kanzikwera, R., Kakuhenzire, R., Hakiza, J.J. and Maniz, G. 2001a. The
effect of crop rotation on Bacterial Wilt incidence and potato yield. African Crop
Science Journal. Vol. 9 (1): 257-266.
• Lemaga, B., Sirri, D and Ebanyat, P. 2001b. Effect of soil amendments on Bacterial
Wilt incidence and yield of potatoes in Southwestern Uganda. Kinya, Z.M., Smith,
J.J., Lung’aho, C., Olanya, F. and Priou, S. 2001. On-farm successes and challenges
on producing Bacterial Wilt-free tubers in seed plots. African Crop Science Journal.
Vol. 9 (1): 279-285.
• Berrios, D. and Rubirigi, A. 1993. Integrated control of Bacterial Wilt in seed
production by the Burundi National Potato Program. ACIAR Proceedings No. 45:
284-288.
• Bizoza, F. 2001. Gestion d’un centre semencier: cas de la ferme semenciere de
Kajondi. In FAO: Techniques de Production, de Protection et de Conservation de
Semences de Pomme de terre. Proceedings of a Seed Potato Workshop held in
Bujumbura, Burundi, 2001.

44. Asante
Thanks
Murakoze
Ameseginalehu!
Contact: dharahagazwe@yahoo.fr
Photo credit: All
photos included in this
presentation, except
the Google map,
belong to the author.