Fusarium Head Blight of Wheat:Progress and Challenges

Ruth Dill-MackyDavid Van Sanford – Erik De Wolf – Pierce Paul

IWC2015 - Sydney Australia

Fusarium Head Blight

re-emerged in 1992

the most important disease to limit wheat production in the

United States

increasing important globally

Fusarium

the most prevalent toxin-producing fungi of the northern temperate

regions

Fusarium toxins are found on infested wheat throughout

America, Europe and Asia

• Fusarium graminearum and other species

• produce mycotoxins

• regulated and effect grain marketing

Hard Red WinterHard Red Spring White Soft Red Winter Durum

USA wheat production areas- shown by class -

1993-1996

yield losses

>2.3 billion USD

Hard Red WinterHard Red Spring White Soft Red Winter Durum

USA wheat production areas- shown by class -

1996 - DON

conversion of all white wheat to

feed

Hard Red WinterHard Red Spring White Soft Red Winter Durum

USA wheat production areas- shown by class -

chronic DON contamination

significant yield losses 1996-2003

USWBSI

Variety DevelopmentGene Discovery & Engineering Resistance

Fungicides Disease Forecasting Models

Pathogen BiologyFood Safety

collaborative research effort since 1997 - funding from USDA 24 states - and grant universities and USDA scientists

Probable causes of the increase in Fusarium Head Blight

reduced tillage practices

susceptible cultivars

expanded corn production

weather patterns

favoring FHB

J F M A M J J A S O N D0

20

40

60

80

100

120

140 '61-90 '93-96

Month

Pre

cip

itati

on

(m

m)

Precipitation PatternsRed River Valley, MN

Wheat and Barley Cultivars

several very popular wheat cultivars were

highly susceptible to FHB

these were not tested during their development

all malt barley cultivars were moderately

susceptible

Fusarium Head Blight

the increase of FHBhas been associated with increased corn

production

and

widespread adoption of reduced tillage

practices

Hard Red WinterHard Red Spring White Soft Red Winter Durum

USA wheat production areas- shown by class -

since 2013

irrigated wheat in rotation with corn

FHB Pathogenspredominance of Fusarium graminearum (Gibberella zeae) as the causal fungus

F. culmorum, F. poae, F. avenaceum, F. equiseti, F. acuminatum, F. sporotrichioides, and others

Fusarium Head Blight

Sporadic epidemics reported in the United States since wheat

production was first established

From a historical perspective FHB was most effectively controlled

from the end of WWII to the mid-1980’s

- the era of the moldboard plow -

PROGRESS

HOST RESISTANCE

Phenotyping

Inoculated Mist-Irrigated Nurseries

Evaluation of FHB response:• Identifying susceptible varieties• Identifying sources of resistance• Screening breeding populations, elite

material and commercial cultivars• Identifying QTL associated with

reduced FHB and mycotoxins

Sources of Resistance

Evaluation of germplasm collections has identified resistance • Sumai 3, Frontana, Freedom, Abura,

16-52-9, Tokai 66

‘Native’ resistance has also been identified• Truman, Bess, Roane and others

Marker Assisted Selection

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RR

RR

Rr

S1

S2

S3

S4

Fun

oS

um

ai

3 CS

DT3

BL

N3

AT3

D N3

DT3

A BA

CR

1R

2R

3R

4

3AS CS3DS CS3BS CS, Sumai 3

3DS Sumai 3

Development of diagnostic markers for

Fhb1

Genotyping CentersThree Regional USDA Labs

Goals:• develop new molecular marker technologies• implement strategies for their application in

breeding• provide access to MAS technologies• maximize the efficiency of small grain

breeding programs

Traits:• quality and disease resistance

Marker Assisted Selection

Markers used for FHB resistanceName Locatio

nQTL Donor Marker

Qfhs.ndsu-3BS 3BS T. aestivum Xbarc133

Qfhs.ifa-5A 5AS T. aestivum Xgwm293

Qfhs.ndsu-3AS 3AS T. dicoccoides

Xgwm2

Qfsh.ndsu-2A 2AL T. aestivum XksuH16

Qfhs.ndsu-4BL 4BL T. aestivum Xwg909

Reaction of Wheat Varieties to FHB - 1996

Reaction of Wheat Varieties to FHB - 2014

Host Resistance – Best Practices

• avoid highly susceptible cultivars

• plant varieties with improved resistance

• diversify - spread in heading dates reduces risk

CHEMICAL CONTROL

Chemical Control

• Heading applications - 50-60% reductions in severity

- Early to mid 1990’s: mancozeb (protectant) and systemic MBC fungicides (benomyl)

- Late 1990’s: Tilt (propiconazole), Folicur (tebuconazole), Quadris (azoxystrobilurin)

- 2000’s: Caramba (metconazole), Proline (prothioconazole), Prosaro (prothioconazole & tebuconazole)

• Application technology - nozzle type & direction

Chemical Control

• Heading applications - 50-60% reductions in severity

- Early to mid 1990’s: mancozeb (protectant) and systemic MBC fungicides (benomyl)

- Late 1990’s: Tilt (propiconazole), Folicur (tebuconazole), Quadris (azoxystrobilurin)

- 2000’s: Caramba (metconazole), Proline (prothioconazole), Prosaro (prothioconazole & tebuconazole)

• Application technology - nozzle type & direction

associated with

increased DON

Fungicides – Best Timings

www.scabsmart.org

Fungicide Spray Angle and Direction

Chemical Control – Best Practices

• recommended fungicides Prosaro, Caramba and Proline – used with an adjuvant

• apply at early flowering (Feekes 10.51)

• application technology

Ground: twin directional nozzles – increase volume for best coverage

Air: use a small droplet size / evening or early morning (dew as additional water)

FHB Prediction Models

Opportunities:

• sporadic disease• plants vulnerable for short period of

time• environment impacts the disease cycle

Temperature

Precipitation

Relative humidity

Solar radiation

Wind

Wetnessduration

Inoculum production

Spore liberation

Sporedispersal

Sporedeposition

Host infection

Host colonization

Residue type Survival

Perithecia Conidiogenesis

Spore maturation

Ascopore release

Conidia release Inoculum level

Inoculum type Rain scrub

Aerodynamics Survival

Attachment Plant

architecture Survival

Host reaction Growth stage

Anthers

Spread within head Growth stage Other hosts

Erick DeWolf, Kansas State University

FHB Prediction Models

weather station

ScabSmart www.scabsmart.org

CULTURAL CONTROL

Residues are problematic as they harbor the initial inoculum from which epidemics

develop

increased corn acreage is likely the major driver of FHB in much of the world

conservation tillage has increased Fusarium survival in host & non-host residues

Fusarium Head Blight

in regions with extended winters

cold reduces microbial resulting in greater inoculum pressure

may also be true for regions with a dry

period

Residue Decomposition

Wheat residues support Fusarium as long as they are ‘recoverable’ - up to three cropping

seasons

Burying residues speeds residue decomposition BUT residues returned to the soil surface

support inoculum production

F. graminearum one of the earlier colonizers of residues - pathogenic phase may give it a competitive advantage as a saprophyte

Crop Residues

Wheat residues likely as good a host as corn

BUT corn residues persist longer

AND Bt-corn may exacerbate this

No-till vs reduced tillage

differences in residue-moisture interactions

Crop Residues

Regional, atmospheric spore populationsmore inoculum than within-field sources

(especially under FHB-conducive environments)

Within-field inoculumimportant in FHB-limiting environmentsbut generally less than 30% of the total

inoculum

Inoculum (debris) management strategiesin individual fields may help reduce FHB & DON

and contribute to integrated management

Host resistance - Fusarium survival

Resistance to FHB in wheat influences the colonization of residues (survival and

inoculum production)

FHB resistance can provide a benefits in future cropping seasons by reducing future inoculum

Avoiding the initial colonization of crops is a better option than trying to reduce Fusarium

levels in residues

Cultural Control – Best Practices

Avoid growing wheat in proximity to cereal debris(follow non-host crops)

Residue management following epidemic years

Plant resistant cereals - reduce Fusarium in debris

What is the contribution of individual practices to the management of

FHB/DON?

Resistant CultivarsFungicides / Prediction Tools Cultural PracticesOther

no single answer for all environments and cropping systems

FHB MANAGEMENT REQUIRES AN INTEGRATED APPROACH

Very susceptible cultivars have been eliminated

Resistance has been improved – BUT immunity is unrealistic and is not alone sufficient to eliminate

risk

Chemical control is needed in the management of FHB

Improved application technologies and forecasting systems have improved our ability to use

fungicides

Future Challenges

Adoption of varieties with improved FHB resistance

Maintaining identity of resistance in some markets

Maintaining/improving resistance over the long term

Ever increasing corn acreage

Limited options for rotations in many production systems

Impact of climate change on Fusarium species

Acknowledgements

Co-Authors:David Van Sanford, University of KentuckyErick De Wolf, Kansas State UniversityPierce Paul, The Ohio State University

USWBSI ColleaguesGary Bergstrom, CornellMarcia McMullen, NDSU

University of MinnesotaJames AndersonRobert BuschDavid GarvinRoger JonesGary MuehlbauerAlbert Sims

University of MinnesotaSmall Grains PathologyMatthew CullerAmar ElakkadC. Kent EvansPravin GautamSilvia PereyraCarlos PerezBacilio SalasBeheshteh Zargaran