Fusarium head blight (FHB) in Brazil:
what have we learned in 15 years?
Emerson M. Del Ponte
Prof. Plant Pathology/Epidemiology
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Major disease of wheat and barley
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FHB
+rain cool
+rain warm
-rain hot
+rain/dry hot
Wheat Blast
90% wheat crops
(5 million T)
Re-emergent in Brazil
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Photo:
Dr. Flávio Santana
Embrapa Trigo
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But also for other crops..
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Trail (2009)
Why does FHB matter?
Trail (2009)
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My FHB research in 6 episodes
A new old problem
Knowing the enemy
The chief species
Food in danger
Man weapons
Statistical modelling
Computer simulation
Disease forecasting
Field surveys
Molecular Identification
Population genetics
Chemistry
Immunology
Pathogen biology and ecology
Plant-pathogen interaction
Fungicide efficacy
Meta-analysis
Economic analysis
Failure ahead?
Fungicide resistance
Phenotypic and molecular
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2
3
4
5
6
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Episode one
A new old problem
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Season Yield losses (%)
1984 - 1994 5.4
2000 17.5
2001 13.4
2002 11.6
2003 26.2
2004 12.0
2005 22.2
2007 39.8
2008 23.2
2009 32.2
2010 17.8
A problem is noticed
E.M. Reis
R.T. Casa
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Del Ponte et al. (2005)
Daily infection risk
Why here, why now? How to predict it?
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Cumulative risk
Model testing
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Cumulative risk
Model testing
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No-till
Cumulative risk
Growing season (year) Del Ponte et al. (2009)
Climate variability effect? no till?
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9 years
11 locations
37 trials
Meta-analysis of damage coefficients
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= 4,419.5 kg ha-1
= -46.3 kg ha-1
= 2,883.6 kg ha-1
= -46.3 kg ha-1
Damage coefficient = -1.05% pp -1 Damage coefficient = -1.60% pp -1
Estimation of damage coefficients
Duffeck et al. (2020)
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Crop simulation
(10 dates x 28 years)
FHB index
FHB
risk
Attainable
yield
Yield
losses
(FHB)
Damage
coefficient (Dc)
-1.05
%
1980-1989 1990-1999 2000-2007
10.3% 10.2%
5.8%
Simulations of historical yield losses
Duffeck et al. (2020)
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FHB index
Fungicide spray
(1x or 2x)
Probability of
non-offsetting costs
$
Actual yield
(Treated)
Actual yield
(Nontreated)
Yield diff.
(kg ha-1)
Are fungicides profitable?
Duffeck et al. (2020)
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Are two sprays worth?
Duffeck et al. (2020)
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Episode Two
Knowing the enemy
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The rise of a species complex
Phylogenetic species recognition based on genealogical concordance
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FGSC species and trichothecene profile
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(Scoz et al 2009; Astolfi et al. 2012; Del Ponte et al. 2015)
> 850 FGSC strains (5 years)
Diverse population of species and toxin types
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(Del Ponte et al. 2015)
Region shaping species distribution?
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South of Paraná: new surveys > 750 isolates
Pereira et al. (2020)
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Crop and year effect on FGSC composition?
Pereira et al. (2020)
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episode Three
Food in danger
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n = 66 samples
2ppm line
Del Ponte et al. (2012)
Trichothecenes in wheat: NIV too!
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Duffeck et al. (2017)
DON by state
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Duffeck et al. (2017)
Zearalenone by state
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Duffeck et al. (2017)
UHPLC vs. Elisa kit
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episode Four
The chief species
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Spolti et al. (2012) Duffeck et al (unpublished)
Is F. graminearum more aggressive?
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Is F. graminearum more aggressive?
F. graminearum F. meridionale
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Machado et al. (unpublished)
Is F. graminearum more aggressive?
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Species x Cultivar = P > 0.05
highly aggressive isolate
Mendes et al. (2018)
Cultivar x species effect?
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Nicolli et al. (2015)
Chemical analysis
Toxigenic potential
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Sexual fertility 1
Nicolli et al. (2015)
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38
* *
Sexual fertility 2
Machado et al. (Unpublished)
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Episode four
Man weapons
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Machado et al. (2017)
Fungicides do work, but varies with AI
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Machado et al. (2017)
Do they protect yield?
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+ 102 kg/ha
Efficacy
(%)
Yield gain
(kg/ha)
Machado et al. (2017)
Estimates of mean efficacy and yield gain
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Does a second spray pay off?
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QoI + DMI mixtures: are they worth?
Barro et al. (2020)
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Yield gain from using mixtures?
Barro et al. (2020)
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Effect size Yield Return (%)
Fungicidea kb D SE(D) CI
L
c CI
U
c P value Y CI
L
c CI
U
c
PYRA + METC 70 532.08 46.40 441.14 623.02 <0.0001 17.17 14.30 20.11
TFLX + PROT 45 494.99 45.09 406.60 583.38 <0.0001 16.21 13.14 19.37
TEBU 25 448.20 54.04 342.27 554.13 <0.0001 14.68 11.24 18.22
AZOX + TEBU 25 462.43 48.92 366.53 558.32 <0.0001 14.74 11.54 18.02
TFLX + TEBU 40 468.24 42.43 385.08 551.41 <0.0001 14.66 11.92 17.46
PYRA + METC
1X
23 413.72 53.66 308.53 518.90 <0.0001 12.97 9.70 16.35
Estimates of mean efficacy and yield gain
Barro et al. (2020)
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Show me the money again
Barro et al. (2020)
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episode six
Failure ahead?
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EC50 levels for 50 strains from RS
Spolti et al. (2012)
Sensitivity to Triazoles (TEBU and METC)
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EC50 levels for 35 strains
R2
R1
R2
Machado et al. (unpublished)
Sensitivity to TEBU and Carbendazim
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F. graminearum less sensitive to TEBU
Machado et al. (unpublished)
R2
R1
R2
F. graminearum others
F. graminearum others
15-ADON
15-ADON
15-ADON
Are EC50 dependent on FGSC species?
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Check
Check
Check
Fungicide
Fungicide
Fungicide
Less sensitive isolates Sensitive isolate
Does it affect control efficacy?
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1. Previous crop not important risk factor in the subtropics (no-till)
2. At least two important species/chemotypes to concern
3. DON and NIV should be a target in surveys (only DON now)
4. One seems more adapted to wheat environments (F. graminearum)
5. Breeders should use the most aggressive strains
Lessons learned
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6. One spray of tebuconazole is a cost-effective choice (yield)
7. Premixes (DMI+QoI) likely do not break even on costs
8. The pathogen may be adapting to fungicides - future concern?
Lessons learned
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Open FGSC database
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Cooperative trial network
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Key Collaborators
Dr. J. Maurício Fernandes
Dr. Gary Bergstrom
Dr. Willingthon Pavan
Dr. Dauri Tessmann
Dr. Todd Ward
Dr. Eliana Furlong
Dr. Casiane Tibola
Dr. Flávio Santana
Dr. Lisa Vaillancourt
Graduate Students (2008 - now)
Paula Astolfi
Piérri Spolti
Paulo R. Kuhnem Jr.
Camila Nicolli
Gabriela Mendes
Franklin Machado
Maíra Duffeck
Jhonatan Barro
Acknowledgements