1. Evaluating Cassava Advanced Lines for Resistance to Cassava Mosaic and Brown Streak Diseases in Tanzania
G. Mkamilo, H. P. Kulembeka, E.E Kanju, G. Matondo, C. S. Jeremiah, E. Masumba, D. Oyena, I. Rwomushana and F. Opio

2. Presentation Outline Importance of cassava in Tanzania
Major biotic constraints
Objective of this study
Breeding approach
Main findings and a Way forward
Acknowledgements

3. Importance of cassava in Tanzania
Tanzania is 4th cassava producer in Africa
Cassava is second in production volume after maize
3. Total root production is 7M tons
4. Over 75% of the total production is used for human food

4. Fig. Cassava production (MT) in each zone in 2007/2008

5. Major Biotic constraints
Cassava Mosaic Disease (CMD)
Cassava Brown Streak Disease (CBSD)
Cassava Green mites (CGM)

6. Cassava Mosaic Disease
CMD is caused by single stranded DNA (ssDNA) of the Geminiviruses (CMGs) (family Geminiviridae; genus Begomovirus)
Reported for the first time in 1894 (118 years) by Warburg
Causing yield loss from % depending on variety

7. Cassava Brown Streak Disease
CBSD is caused by a single stranded RNA (ssRNA) virus in the family of Potyviridae; genus Ipomovirus
Reported for the first time in 1930s (82 years) by Storey in Tanzania
Crop losses of up to 74% (Muhanna and Mtunda, 2002) reported in Tanzania

8. Table 1. Cassava productivity and production, and cropping area remain constant for 14 years

9. Management of cassava virus diseases
The most realistic approach to reducing losses to Cassava Mosaic Disease (CMD) and Cassava Brown Streak Disease (CBSD) is the use of host-plant resistance or deployment of less-susceptible cultivars (Hillocks 2002).

10. Specific Objective
To evaluate eleven cassava advanced lines for resistance to cassava mosaic and brown streak diseases in Tanzania

11. Breeding Approach
Hybridization of CMD/CBSD resistant parents and farmer preferred varieties
Screening 11 advanced lines for CMD and CBSD resistance between 2009 to 2011 at ARI Naliendele; a location with high CMD/CBSD pressure
CMD and CBSD were assessed according to IITA (1990 ) and Hillocks et al (1996).

12. Research site
Agricultural Research Institute (ARI) Naliendele in Mtwara, Tanzania

13. Evaluating cassava lines at ARI Naliendele in Mtwara, Tanzania

14. Breeding Approach
Data on root yield and related traits were also collected at harvest.
Data were subjected to analysis of variance and treatment means were separated using least significant difference test.

15. Table 2 Pedigree of advanced cassava lines evaluated in Tanzania 2009-2011
Clone
Female parent
Male parent
Remarks
KBH 2002/477
Kiroba
Unknown
Half sib
KBH 2002/482
KBH 2002/494
KBH 96/1056
Uknown
KBH 96/108
NR85200
Kigoma Red
Landrace
Naliendele
Kibaha
NDL 2003/031
Nanchinyaya
Full Sib
NDL 2003/111
Namikonga
Kalulu
NDL 2005/1471
NDL 2005/1472
NDL 2005/201
Namkonga
Full sib
NDL 2005/492

16. Main Findings
There was significant differences for CMD, CBSD root necrosis and CBSD shoot infection among clones.
Over 70% of advanced lines indicated field resistance against CBSD and CMD
Significant differences were also revealed among clones for fresh root yield, number of roots per plant and harvest index
Generally, four advanced lines out-yielded control check Kiroba

17. Table 3. Four outstanding cassava advanced lines
Yield (t/ha) DM (%)
1. KBH 2002/
2. KBH 96/
3. NDL 2003/
4. NDL 2005/
5. KIROBA (Check)

18. A way forward
Further evaluation of four superior cassava advanced lines at various agro-ecologies with involvement of farmers for official release and commercialization

19. Acknowledgement ASARECA for financial support
IITA for technical backstopping
Research Team for hard work

20. THANK YOU