Presented at the Annual Congress of Grassland Society of Southern Africa, Upington, South Africa, 30 June - 4 July 2019

1. Emerging Disease Challenges to Sustainable
Production of Brachiaria Grass in Rwanda
B. Uzayisenga, M. Mutimura, J. W. Muthomi
A. W. Mwang'ombe & S. R. Ghimire
Annual Congress of Grassland Society of Southern Africa
Upington, South Africa
30 June - 4 July 2019

2. Introduction
▪ Agriculture is backbone of Rwanda
▪ Livestock contributes 3% of national GDP
▪ Low livestock productivity contributed
mainly by limited pasture land, shortage
of quality feeds especially in dry season,
Napier grass diseases and climate change
▪ Brachiaria grass is the fodder promoted in
Rwanda to alleviate livestock feed
shortage
▪ Diseases are observed as an emerging
challenge for Brachiaria production
▪ Very little known about Brachiaria
diseases in Rwanda, and in SSA in general
Njarui et al., 2016

3. Objectives
▪ To evaluate farmers’ knowledge on Brachiaria grass
diseases
▪ To assess incidence, severity and distribution of
Brachiaria grass diseases in Rwanda

4. Materials and methods
Map showing locations of surveyed districts (Huye,
Nyamagabe, Bugesera, Kayonza and Rwamagana)
▪ Five districts
▪ Two seasons: dry and wet
▪ Dry season: 25 fields
▪ Wet season: 75 fields
▪ Physical, agronomic and
social data collection
▪ Social information:
o Age
o Gender
o Marital status
o Education level
Survey for Brachiaria diseases

5. Materials and methods
Assessment of
Disease
incidence and
severity
Information collection Farmer explains about his field
20 stools per field from
four different quadrats

6. Materials and methods
Table 1. Scale for scoring the severity of disease
Disease Scale Reference
Leaf blight 0 to 5 CIAT, 2004
Leaf spot 0 to 4 Stubbs et al., 1986
Rust 0 to 7 CIMMYT, 1985
Recording of disease incidence
▪ Observations of 20 stools from four different square meter quadrats
▪ Incidence was calculated as the percentage of the infected plants in
comparison with all observed stools

7. Results
District Av. age
(yrs.)
Gender (%) Marital status (%) Education level (%)
Male Female Married Single Widow Primary Secondary Tertiary
Huye 41.7 40.0 60.0 80.0 13.3 6.7 40.0 53.3 6.7
Nyamagabe 50.2 80.0 20.0 66.7 26.7 6.7 40.0 53.3 6.7
Bugesera 45.5 60.0 40.0 100.0 0.0 0.0 93.3 6.7 0.0
Rwamagana 48 60.0 40.0 100.0 0.0 0.0 93.3 6.7 0.0
Nyagatare 46.1 61.5 38.5 92.3 7.7 0.0 69.2 23.1 7.7
Mean 46.3 60.3 39.7 87.7 9.6 2.7 67.1 28.8 4.1
Characteristics of farmers interviewed during Brachiaria disease survey

8. Results
District Disease Yield loss
Free Present Below 5% 25-50%
Huye 80.0 20.0 0.0 20.0
Nyamagabe 80.0 20.0 0.0 20.0
Bugesera 40.0 60.0 40.0 20.0
Rwamagana 86.7 13.3 13.3 0.0
Nyagatare 73.3 26.7 26.7 0.0
Mean 72.0 28.0 16.0 12.0
Farmer knowledge on Brachiaria diseases & impact of diseases on forage
production

9. Results
Farmer knowledge on disease symptoms
Symptoms Districts Total
Huye Nyamagabe Bugesera Rwamagana Nyagatare
Bad growth 0.0 0.0 6.7 0.0 0.0 1.3
Drying of leaves 0.0 0.0 0.0 6.7 0.0 1.3
Holes on leaves 0.0 0.0 0.0 0.0 6.7 1.3
Yellowing of
leaves
0.0 6.7 53.3 6.7 20.0 17.3
Yellowing &
drying of leaves
13.3 13.3 0.0 0.0 0.0 5.3
Do not know 86.7 80.0 40.0 86.7 73.3 73.3
Total 100.0 100.0 100.0 100.0 100.0 100.0

10. Results
Diseases recorded
in survey
Leaf spot Rust
Ergot Virus like Leaf blight

11. Results
Fig.1. Prevalence of major diseases
B. Prevalence of rust
c. Prevalence of leaf spot
A. Prevalence of leaf blight

12. Results
Fig.2. Incidence of major diseases in dry season
0
10
20
30
40
50
60
70
80
90
100
Huye Nyamagabe Bugesera Rwamagana Nyagatare
Diseaseincidence(%)
Districts
Leaf blight
Rust
Leaf spot
a
a
a
a
c
b
c b
b
b
b
c
b
b
c

13. Results
Fig.3. Incidence of major diseases in wet season
-
10
20
30
40
50
60
70
80
Huye Nyamagabe Bugesera Rwamagana Nyagatare
Diseaseincidence(%)
Districts
Leaf blight
Rust
Leaf spot
d
a
b
c
a
a
b ab
a
c
b
b
d
d
c

14. Results
Fig.4. Severity score of major diseases in dry season
0
0.5
1
1.5
2
2.5
Huye Nyamagabe ` Bugesera Rwamagana Nyagatare
Diseaseseverityscore
Districts
Leaf blight
Rust
Leaf sport
b
c
c
b
b
b
b
c
b
b
a
a
aa
c

15. Results
Fig.5. Severity score of major diseases in wet season
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Huye Nyamagabe ` Bugesera Rwamagana Nyagatare
Diseaseseverityscore
Districts
Leaf blight
Rust
Leaf sport
b
a
a
a
b
c
b b
a
b
b
c
c
c
c

16. Conclusion and recommendations
Rust spore collection
▪ Leaf blight and rust were found widespread in all surveyed
districts
▪ The incidence was 55.6% and 45.7%; 30.6% and 32.6% for leaf
blight and rust respectively ( dry and rainy seasons)
▪ Leaf blight, leaf spot and rust were found as major Brachiaria
diseases in Rwanda
▪ Identification of associated causal agents and evaluation of
disease management options are high priority for sustainable
management of Brachiaria diseases

17. Acknowledgement
▪ The BecA – ILRI
▪ The Swedish International Development Cooperation Agency (Sida)
▪ University of Nairobi
▪ Supervisors: Prof. James W. Muthomi, Prof. Agnes W.
Mwang’ombe, Dr. Mutimura Mupenzi, and Dr. Sita R. Ghimire.
▪ Rwanda Agriculture and Animal Resources Development Board
▪ Farmers in surveyed districts
▪ GSSA Conference organizers

18. Thank you