1. Integration of Maize Lethal Necrosis Disease Management in Crop/Livestock Intensification to Enhance Productivity of Smallholder Agricultural Production Systems in East Africa
Bright Jumbo1, Lava Kumar2, Dan Makumbi1, Yangole Luhenda3 and M. Bekunda2
1International Maize and Wheat Improvement Centre (CIMMYT)
2International Institute of Tropical Agriculture (IITA)
3SELIAN Agricultural Research Institute
June 30 to July 2, 2016
AfricaRISING Annual Planning Meeting, Dar Tanzania

2. Study Objectives
Establish the incidence and prevalence of MLN in three key maize growing regions of Tanzania which fall under three different climatic categories, Arusha (wet most of the seasons), Dodoma (semi-Arid) and Manyara (intermediate), map the areas affected by MLN
Establish MLN impact on yield and other agronomic traits
Identify MLN tolerant maize varieties and test their adaptability

3. Geographic coverage Sub-Humid District (1610 to 2178 mts)
Assessment of maize lethal necrosis in AfricaRISING target areas
Sub-Humid District
(1610 to 2178 mts)
Geographic coverage
Semi-Arid Districts
( mts)
Medium elevation

4. Materials and Methods
Two surveys were conducted in three regions (Manyara, Arusha and Dodoma)
130 farms were sampled, leaf samples from symptomatic plants were brought to lab for ELISA
The surveys were done during short season and main season
Hybrids were evaluated in 156 trials using alpha lattice design

5. MLN prevalence in 2015 crop season
Widespread and expanding; incidence between 5 to >70%

6. Prevalence of maize lethal necrosis and maize streak in 2015 crop season (N = 130)
Percent

7. Prevalence and incidence of maize lethal necrosis in 2015 crop season (N = 130)
Percent incidence
Babati
Manyara
Dodoma
Arusha

8. Prevalence of maize lethal necrosis, maize streak virus and other viruses in 2015 crop season (N = 130)

9. MLN Survey Results by Seasons (Long Vs Short)
Total fields assessed
MLN prevalence %
MLN incidence %
MLN severity (mean)
MSV prevalence %
MSV incidence%
MSV severity (mean)
Short dry season
(Feb – Mar) 34
79.4
19.8
2.3
44.1
15.6
2.7
Main rainy season
(May-Jun)
126
69.0
24.9
2.4
45.2
11.5
2.5
Total/Mean
160
74.2
22.4
44.7
13.6
2.6

10. Survey results based on cropping systems
Number of fields
MLN severity (mean)
MLN incidence (%)
MSV severity (mean)
MSV incidence (%)
Maize Sole crop 61
2.4 25
2.5
12.1
Maize inter cropped with legumes and cereals 99
2.3 22
2.6
11.8

11. MLN Survey Results by District
Prevalence, incidence and severity of maize virus diseases during minor maize season (2015)
Region
District
No. of fields
Virus incidence (%)
virus disease severity
MLN prevalence
MLN severity (%)
MLN Incidence (%)
MSV prevalence
MSV severity
MSV Incidence (%)
Arusha
Meru 8
60.4
2.7
100
2.5 35
7.5
2.8 29
Manyara
Babati 10 20
2.1 90 2 17 30
Mbulu 5 23
2.3 80
2.2 40 13
Dodoma
Kongwa 6
2.4
66.6 4
33.3 3
Mpwapwa 7
57.1
42.8
Total 36
23.8
78.7
15.8
30.8
11.8
Note: In each field 30 plants were assessed; MSV = maize streak virus; MLN = maize lethal necrosis; incidence is expressed as % infected plants of the total plants assessed; and symptom severity is assessed based on 1 to 5 rating scale, where 1 = no symptoms and 5 = most severe symptoms

12. MLN Survey Results by District
Incidence and severity of maize viruses on various cultivars observed during minor maize season surveys (2015) based on Variety
Variety
Total fields observed
Virus incidence (%)
Mean severity
MLN Incidence (%)
MLN severity
MSV Incidence (%)
MSV severity
Local 12 14 2 11 3 1
SC627 5 15
STAHA 8 6
Stuka 33 10 23
TMV-1
unknown 68 40 27
DK8031 22
Kaspino 60
2.6 53
2.4 7
3.5
Kiboseed 5013 73
2.7
3.1
2.2
Pannar
2.3
2.5
SC719 37
Note: In each field 30 plants were assessed; MSV = maize streak virus; MLN = maize lethal necrosis; incidence is expressed as % infected plants of the total plants assessed; and symptom severity is assessed based on 1 to 5 rating scale, where 1 = no symptoms and 5 = most severe symptoms

13. MLN Survey Results by growing period (months)
Number of fields
MLN severity (mean)
MLN incidence (%)
MSV severity (mean)
MSV incidence (%)
1 to 2 months 18
2.3 25
2.2
9.3
2 to 3 months
127
23.1
2.6
12.6
>3 months 9
2.4
27.8
2.5
16.7

14. Table1. Maize Yield Losses Associated with MLN-Babati
Pedigree
Grain Yield
(tha-1)†
(tha-1)
MLN
Percent Drop in Yield
(%)
Ear Aspect (1-5)
Number of Plants plot-1
SYN(B)F2-5-8/CML539/CML442
7.6 2
73.7
2.8 22 18
SYN(B)F2-17-1/CML539/CML442
7.2
2.2
69.4 3 14
SYN(B)F2-14-3/CML539/CML442
7.1
1.8
74.6
2.7 15
SYN(B)F2-17-4/CML539/CML442
69.0 16
SYN(B)F2-19-4/CML539/CML442
1.6
77.5
SYN(B)F /CML539/CML442
2.4
SYN(B)F2-5-5/CML539/CML442
7.0
2.9
58.6
3.4
SYN(B)F2-23-5/CML539/CML442
2.1
70.0
SYN(B)F2-22-3/CML539/CML442
1.4
80.0
3.3 21 13
SYN(B)F2-5-1/CML539/CML442
1.5
78.6
3.6 12
SYN(B)F2-5-4/CML539/CML442
1.1
84.3
3.5
SYN(B)F /CML539/CML442
1.3
81.4
2.6 4 17
SYN(B)F2-9-1/CML539/CML442
6.9
78.3
SYN(B)F2-6-6/CML539/CML442
2.5
63.8
3.2
SYN(B)F2-12-2/CML539/CML442
84.1
4.1 8
SYN(B)F2-12-3/CML539/CML442
81.2 11
SYN(B)F2-17-3/CML539/CML442
71.0
3.1
SYN(B)F /CML539/CML442
6.8
1.7
75.0
SYN(B)F2-7-1/CML539/CML442
67.6
SYN(B)F2-7-3/CML539/CML442
SYN(B)F2-11-8/CML539/CML442
0.4
94.1
Comercial Check
6.0
0.9
85.0
3.0
4.2
Experiment Mean
6.4
1.60
LSD (0.05)
2.3
1.33*
42.2
0.8
1.1* CV
18.8
41.85
13.6
16.0 30

16. Number of plants per row
Table 2. Mean Grain yield and other important agronomic traits for the top performing hybrids among several hybrids evaluated in 56 Trials at Mara Farm in Babati under natural MLN infestation.
Pedigree
Grain Yield
†(thha-1)
Ears plant-1
Ear Rot
(%)
Number of plants per row
Ear Aspect ‡1-5 scale
CKH140117
2.4
1.1 50
13.9
3.5
CKH140098
1.9
0.8 63
16.6
CKH140107 59
11.9
CKH140031
1.7 1 74
12.1
3.7
CKH140105 72 13
CKH140035
1.6
0.7 67
11.5
CKH140017
1.5
0.9 71
CKH140106
1.3
1.2 80 14
CKH140124 85
12.4
4.2
CKH140032 79 4
CKH140018 70
13.4
CKH140003 98
12.3 5
CKH140015 66
12.8
CKH140011
0.6 56
11.8
4.5
H513
0.3
0.1 -1 7
H520
0.0
0.2 97
12.2
Experiment Mean
0.48
0.68
83.7 12
LSD (0.05)
1.34*
0.55**
31.9*
4.8***
1.2NS CV
139.71
40.6
18.1 20
13.1
Num Reps 2
*Significant at P<0.05, **P<0.01, ***P<0.001; †Tons per hectare; ‡1 = good, 5=worse. Highlighted in blue are commercial checks.

17. More data this season We have hybrids still in 26 trials
We plan to perform combined analysis for all the data from evaluation based on same trial

18. Summary
MLN is a complex issue that requires integrated efforts involving researchers, maize producers, seed suppliers, policy makers, crop regulatory authorities to work together for measures to be effective
We need an integrated and comprehensive approach that includes use of host resistance, strong sensitization on importance of using certified seed, applying good agricultural management practices, good pest management, inspection of fields to remove diseased plants at early stages, encouraging crop rotation and timely planting

19. Lets all joins hands and work together to defeat MLN and keep maize healthy!
Thank you!