Outbreak of Fusarium ear rot on Maize in Thailand. Warapon Bunkoed

1. Outbreak of Fusarium ear rot on Maize in Thailand
Warapon Bunkoed1,2, Patcharavipa Chaijuckam2, Supot Kasam2, Sodsai Changsaluk1,
Jeeranan Yhamsoongnern1 and Sutruedee Prathuangwong2*
KU Corn and Sorghum Research Center,
Kasetsart University

2. Fusarium ear rot

3. Objectives
 Identification the fungal that causal agent to Fusarium ear rot in
Thailand.
 Evaluation disease severity of Fusarium ear rot in mainly cultivated for
maize productions.
 Evaluation of host resistance for pathogen infection of maize inbred lines
and hybrid pre-commercial variety.

4.  Sample collection
Materials and Methods
The occurrence of ear rot of maize was determined over a 2- year
(2016-2017) growing seasons from fields in 6-key locations

5. Table 1 Distribution of 138 isolate of Fusarium spp., disease
incidence and disease severity of each location in 2016.
Geographic Origin Number of
isolate
Disease
incidence
Disease
severity
1. Chuntuk, Pak Chong,
Nakhon Ratchasima
23 100% 38%
2. Pak Chong, Pak Chong,
Nakhon Ratchasima
23 25% 9%
3. Nong Bun Mak,
Nakhon Ratchasima
23 100% 28%
4. Phop Phra, Tark 23 100% 35%
5. Muak Lek, Saraburi 23 27% 8%
6. Khok Charoen, Lop Buri 23 26% 5%

6. 7 days on PDA
MGA 2.5 + carnation leaf
pieces
Identification and isolation
Materials and Methods

7. Fusarium verticillioides
Macro conidia
Micro conidia

8.  Fusarium verticillioides (teleomorph Gibberella moniliformis) is
the main fungal agent of ear and kernel rot of maize
 F. verticillioides causes seedling decay, stalk rot, ear rot in maize.
 F. verticillioides is a highly toxigenic species since it is able to
produce the carcinogenic mycotoxin (fumonisins).

9. Inbred evaluation experiment
 A set of 60 inbred lines from National Corn and Sorghum
Research Center (NCSRC), Kasetsart Univercity evaluated in rainy
season (2016) at NCSRC
 Plots were arranged as RCBD with three replications.

10.  The silk channel inoculation (SILK)
method described by Reid et al., (1993)
 2 ml of a conidial suspension of
F.verticilliodes at 105 conidia/ml were
injected with blunt needle into the silk
channels of individual ears.

11. • Individual plots were 5 m long, 3 m wide and consisted
in four rows planted to 25 seeds per row.
• At maturity, when kernel moisture was less than 25%,
ears were manually harvested.
• The severity of F.verticilliodes
infection was measured using the
disease rating of Reid and Hamiton (1996)
as follows:
• 1=0% infection
• 2=1-3%
• 3=4-10%,
• 4=11-25%,
• 5=26-50%,
• 6=51-75%
• 7=76-100%.

12. Inbred Lines Mean of disease severity score Inbred Lines Mean of disease severity score
Ki1 4.3 Ki31 5.0
Ki2 4.0 Ki32 7.0
Ki3 4.3 Ki33 4.0
Ki4 5.0 Ki34 7.0
Ki5 5.6 Ki35 7.0
Ki6 4.0 Ki36 4.3
Ki7 4.0 Ki37 7.0
Ki8 4.0 Ki38 6.6
Ki9 7.0 Ki39 6.3
Ki10 7.0 Ki40 6.3
Ki11 6.3 Ki41 4.0
Ki12 4.3 Ki42 4.6
Ki13 5.0 Ki43 5.0
Ki14 4.0 Ki44 5.6
Ki15 5.3 Ki45 4.6
Ki16 5.0 Ki46 6.3
Ki17 7.0 Ki47 5.0
Ki18 4.0 Ki48 7.0
Ki19 6.0 Ki49 7.0
Ki20 5.3 Ki50 6.6
Ki21 6.6 Ki51 7.0
Ki22 4.0 Ki52 4.0
Ki23 6.3 Ki53 5.6
Ki24 N Ki54 7.0
Ki25 7.0 Ki55 7.0
Ki26 7.0 Ki56 5.3
Ki27 4.0 Ki57 7.0
Ki28 7.0 Ki58 6.6
Ki29 7.0 Ki59 6.6
Ki30 2.6 Ki60 7.0

13. Ki59
Ki30
Ki45

14. Hybrid evaluation experiment
 The screening of hybrids was conducted under field trials under
rainy and dry seasons in 2016.
 Maize hybrid (20-precommercial plus 3-commercial) varieties from
National Corn and sorghum Research Center were screen by
natural disease prevalence at 6 locations in 4 provinces.

15.  The field set up for all experiments were arranged as RCBD
with three replications.
 Individual plots were 5 m long, 3 m wide and consisted in
four rows planted to 25 seeds per row.

16.  When plant reached physiological maturity, all cobs were
harvested per variety.
 Immediately after harvesting, maize ear rot infections were
evaluated on site based on the symptoms or nature of
damage. Disease severity (DS) of cob rot in each ear in the
sample was assessed using the disease rating of Reid and
Hamiton (1996)

17. Table 2 Disease incidence and disease severity of Fusarium ear rot on pre-commercial field corn in 2016
Locations
Maize cultivars
Chuntuk,
Pak Chong
Nakhon Ratchasima
Pak Chong,
Pak Chong
Nakhon Ratchasima
Nong Bun Mak
Nakhon Ratchasima
Phop Phra
Tark
Muak Lek
Saraburi
Khok Charoen
Lop buri
DI1/ DS2/ DI DS DI DS DI DS DI DS DI DS
1. KSX5402 100 6.3 20.0 2.6 100 5.3 100 4.6 22.3 3.0 30.0 2.0
2. KSX5603 100 5.0 30.3 4.3 100 6.0 100 5.0 40.7 3.6 20.0 2.0
3. KSX5614 100 4.3 24.3 3.0 100 4.0 100 3.3 30.3 3.3 31.0 2.0
4. KSX5720 100 3.6 30.0 3.0 100 3.6 100 3.3 20.0 2.0 20.0 2.0
5. KSX5805 100 5.6 44.3 4.3 100 6.0 100 6.0 30.6 3.3 21.0 2.0
6. KSX5819 100 4.6 20.0 2.6 100 5.0 100 4.3 23.3 2.3 35.0 2.3
7. KSX5901 100 6.0 28.0 3.6 100 5.0 100 5.3 65.0 4.6 21.6 2.0
8. KSX5902 100 5.0 33.0 4.0 100 6.0 100 3.3 25.0 2.0 20.0 2.0
9. KSX5903 100 4.6 16.0 2.6 100 4.6 100 4.6 34.3 3.3 39.3 2.3
10. KSX5904 100 5.0 N N 100 4.3 100 5.3 26.6 2.6 21 2.0
11. KSX5906 100 5.0 12.3 2.6 100 5.6 100 5.0 31.6 3.0 26.6 2.0
12. KSX5908 100 4.3 17.6 3.0 100 5.3 100 4.3 23.3 2.3 31.6 2.3
13. KSX5909 100 4.3 20.0 2.6 100 4.6 100 3.0 33.3 3.3 41.0 3.6
14. KSX5911 100 4.0 23.6 3.0 100 4.0 100 4.0 13.0 1.6 20.0 1.6
15. KSX5912 100 4.6 20.0 3.0 100 5.0 100 3.6 18.6 2.0 19.7 1.6
16. KSX5919 100 4.6 18.0 2.3 100 4.6 100 4.3 25.0 3.0 20.0 2.0
17. KSX5924 100 4.6 30.0 3.3 100 5.0 100 4.3 31.0 3.0 50.0 3.6
18. KSX5927 100 5.3 43.3 4.0 100 6.0 100 5.0 28.3 3.3 20.3 3.0
19. KSX5934 100 5.3 22.6 3.3 100 6.0 100 5.3 24.3 3.0 23.3 3.0
20. KSX5937 100 5.0 53.3 4.0 100 4.6 100 4.0 18.3 3.0 24.7 2.3
21. NS3 100 4.0 15.6 2.6 100 2.6 94.3 3.3 13.3 2.6 20.3 2.0
22. CP888 100 3.6 10.0 2.0 100 3.6 91.7 2.6 22..3 2.6 22.7 1.6
23. SW4452 100 5.0 10.0 2.6 100 4.3 96.7 3.6 20.0 3.3 26.7 2.3

18. Table 2 Disease incidence and disease severity of Fusarium ear rot on pre-commercial field corn in 2016
Locations
Maize cultivars
Chuntuk,
Pak Chong
Nakhon Ratchasima
Pak Chong,
Pak Chong
Nakhon Ratchasima
Nong Bun Mak
Nakhon Ratchasima
Phop Phra
Tark
Muak Lek
Saraburi
Khok Charoen
Lop buri
DI1/ DS2/ DI DS DI DS DI DS DI DS DI DS
1. KSX5402 100 6.3 20.0 2.6 100 5.3 100 4.6 22.3 3.0 30.0 2.0
2. KSX5603 100 5.0 30.3 4.3 100 6.0 100 5.0 40.7 3.6 20.0 2.0
3. KSX5614 100 4.3 24.3 3.0 100 4.0 100 3.3 30.3 3.3 31.0 2.0
4. KSX5720 100 3.6 30.0 3.0 100 3.6 100 3.3 20.0 2.0 20.0 2.0
5. KSX5805 100 5.6 44.3 4.3 100 6.0 100 6.0 30.6 3.3 21.0 2.0
6. KSX5819 100 4.6 20.0 2.6 100 5.0 100 4.3 23.3 2.3 35.0 2.3
7. KSX5901 100 6.0 28.0 3.6 100 5.0 100 5.3 65.0 4.6 21.6 2.0
8. KSX5902 100 5.0 33.0 4.0 100 6.0 100 3.3 25.0 2.0 20.0 2.0
9. KSX5903 100 4.6 16.0 2.6 100 4.6 100 4.6 34.3 3.3 39.3 2.3
10. KSX5904 100 5.0 N N 100 4.3 100 5.3 26.6 2.6 21 2.0
11. KSX5906 100 5.0 12.3 2.6 100 5.6 100 5.0 31.6 3.0 26.6 2.0
12. KSX5908 100 4.3 17.6 3.0 100 5.3 100 4.3 23.3 2.3 31.6 2.3
13. KSX5909 100 4.3 20.0 2.6 100 4.6 100 3.0 33.3 3.3 41.0 3.6
14. KSX5911 100 4.0 23.6 3.0 100 4.0 100 4.0 13.0 1.6 20.0 1.6
15. KSX5912 100 4.6 20.0 3.0 100 5.0 100 3.6 18.6 2.0 19.7 1.6
16. KSX5919 100 4.6 18.0 2.3 100 4.6 100 4.3 25.0 3.0 20.0 2.0
17. KSX5924 100 4.6 30.0 3.3 100 5.0 100 4.3 31.0 3.0 50.0 3.6
18. KSX5927 100 5.3 43.3 4.0 100 6.0 100 5.0 28.3 3.3 20.3 3.0
19. KSX5934 100 5.3 22.6 3.3 100 6.0 100 5.3 24.3 3.0 23.3 3.0
20. KSX5937 100 5.0 53.3 4.0 100 4.6 100 4.0 18.3 3.0 24.7 2.3
21. NS3 100 4.0 15.6 2.6 100 2.6 94.3 3.3 13.3 2.6 20.3 2.0
22. CP888 100 3.6 10.0 2.0 100 3.6 91.7 2.6 22..3 2.6 22.7 1.6
23. SW4452 100 5.0 10.0 2.6 100 4.3 96.7 3.6 20.0 3.3 26.7 2.3

19. Table 2 Disease incidence and disease severity of Fusarium ear rot on pre-commercial field corn in 2016
Locations
Maize cultivars
Chuntuk,
Pak Chong
Nakhon Ratchasima
Pak Chong,
Pak Chong
Nakhon Ratchasima
Nong Bun Mak
Nakhon Ratchasima
Phop Phra
Tark
Muak Lek
Saraburi
Khok Charoen
Lop buri
DI1/ DS2/ DI DS DI DS DI DS DI DS DI DS
1. KSX5402 100 6.3 20.0 2.6 100 5.3 100 4.6 22.3 3.0 30.0 2.0
2. KSX5603 100 5.0 30.3 4.3 100 6.0 100 5.0 40.7 3.6 20.0 2.0
3. KSX5614 100 4.3 24.3 3.0 100 4.0 100 3.3 30.3 3.3 31.0 2.0
4. KSX5720 100 3.6 30.0 3.0 100 3.6 100 3.3 20.0 2.0 20.0 2.0
5. KSX5805 100 5.6 44.3 4.3 100 6.0 100 6.0 30.6 3.3 21.0 2.0
6. KSX5819 100 4.6 20.0 2.6 100 5.0 100 4.3 23.3 2.3 35.0 2.3
7. KSX5901 100 6.0 28.0 3.6 100 5.0 100 5.3 65.0 4.6 21.6 2.0
8. KSX5902 100 5.0 33.0 4.0 100 6.0 100 3.3 25.0 2.0 20.0 2.0
9. KSX5903 100 4.6 16.0 2.6 100 4.6 100 4.6 34.3 3.3 39.3 2.3
10. KSX5904 100 5.0 N N 100 4.3 100 5.3 26.6 2.6 21 2.0
11. KSX5906 100 5.0 12.3 2.6 100 5.6 100 5.0 31.6 3.0 26.6 2.0
12. KSX5908 100 4.3 17.6 3.0 100 5.3 100 4.3 23.3 2.3 31.6 2.3
13. KSX5909 100 4.3 20.0 2.6 100 4.6 100 3.0 33.3 3.3 41.0 3.6
14. KSX5911 100 4.0 23.6 3.0 100 4.0 100 4.0 13.0 1.6 20.0 1.6
15. KSX5912 100 4.6 20.0 3.0 100 5.0 100 3.6 18.6 2.0 19.7 1.6
16. KSX5919 100 4.6 18.0 2.3 100 4.6 100 4.3 25.0 3.0 20.0 2.0
17. KSX5924 100 4.6 30.0 3.3 100 5.0 100 4.3 31.0 3.0 50.0 3.6
18. KSX5927 100 5.3 43.3 4.0 100 6.0 100 5.0 28.3 3.3 20.3 3.0
19. KSX5934 100 5.3 22.6 3.3 100 6.0 100 5.3 24.3 3.0 23.3 3.0
20. KSX5937 100 5.0 53.3 4.0 100 4.6 100 4.0 18.3 3.0 24.7 2.3
21. NS3 100 4.0 15.6 2.6 100 2.6 94.3 3.3 13.3 2.6 20.3 2.0
22. CP888 100 3.6 10.0 2.0 100 3.6 91.7 2.6 22..3 2.6 22.7 1.6
23. SW4452 100 5.0 10.0 2.6 100 4.3 96.7 3.6 20.0 3.3 26.7 2.3

21. Table 3 Fusarium ear rot severity and fumonisin concentration of 8
commercial maize hybrids evaluated after harvest in 2017
District
Commercial
maize hybrid
Si Satchanalai Pak Chong Tak Fa1 Tak Fa2 Wang Thong
Fusarium
ear rot
Fumonicin
(ppm)
Fusarium
ear rot
Fumonicin
(ppm)
Fusariu
m ear rot
Fumonicin
(ppm)
Fusariu
m ear rot
Fumonicin
(ppm)
Fusariu
m ear rot
Fumonicin
(ppm)
1. PAC139 21/
11.83 2 0.17 3 0.93 2 4.47 4 20.61
2. PAC129 2 1.42 2 4.07 3 1.41 2 2.05 2 0.56
3. CP888 2 1.03 2 0.21 2 0.06 2 5.91 2 3.37
4. DK9898 2 0.50 3 1.0 3 0.85 3 7.58 3 8.74
5. NS3 2 3.00 2 1.99 2 0.25 2 1.14 3 0.58
6. PAC559 2 8.25 3 2.29 3 1.89 3 5.11 4 5.70
7. SW4452 2 3.64 2 1.65 3 1.47 4 1.48 5 1.48
8. DK6818 2 0.71 3 2.25 3 5.73 3 2.63 4 1.69
1/ Mean of disease severity score (1=0% infection, 2=1-3%, 3=4-10%, 4=11-25%, 5=26-50%, 6=51-75%, and 7=76-100%).

22. Conclusions
 Fusarium ear rot of maize in Thailand caused by Fusarium
verticillioides.
 Among inbred lines tested, only Ki30 showed less severe to ear
rot inoculation.
 Two-precommercial cultivars, KSX5720 and KSX5911 possibly
revealed resistance tendency present a less severity level.
 The high fumonisin on affected grains was detected in some
location samples with over the 5 ppm concentration levels
using the direct competitive ELISA assay.

23. Acknowledgments
 Kasetsart University Research and Development Institute
 National corn and Sorghum Research Center