Oilseed rape diseases, climate change, spread

and food security

Bruce Fitt1,2, Neal Evans2, Peter Gladders3, David Hughes1,2, Yong-JuHuang1,2, Jon West2, Ralph Lange4, Prem Kharbanda4

1 University of Hertfordshire, Hatfield, UK2 Rothamsted Research, Harpenden, UK3 ADAS Boxworth, nr. Cambridge, UK4 Alberta Research Council, Canada

Email: b.fitt@herts.ac.uk

Crop diseases threaten food security

• Crop losses to diseases decrease global food production despite

crop protection (16%, Oerke, J. Agr. Sci., 2006; FAO, 2010)

Diseases,

pests,

weeds

etc.

Actual crop losses

(with crop protection)

Potential crop losses

(without crop protection)

% £bn % £bn

Rice 37 74 77 154

Wheat 28 31 50 56

Maize 31 18 40 23

Potato 40 21 75 40

• Population 6 billion people AND

1 billion with not enough to eat FAO, 2009

Challenge - If global crop losses are decreased by 1%, an extra 25M

people will have enough to eat, without extra use of resources

(land,water etc.) (CABI, annual report, 2009/10)

Impacts of climate change on agricultural productivity by 2080sCline WR (2007), Global warming & agriculture; impact estimates by country

Climate change threatens food security

Climate change - Increased CO2, increased temperature

Air temperature at Rothamsted, Harpenden, UK

Oilseed rape diseases, climate change, spread and food security

1. Climate change adaptation: How can we be prepared for future impacts of climate change on disease epidemics and food security?

2. Disease spread; how can it be minimised?

3. Climate change mitigation: Can crop disease control reduce greenhouse gas emissions now?

Climate change can affect crop diseases

Crop(resistance)

Pathogen(changing population)

Environment(changing climate)

Disease

severity

Climate change scenarios

IPCC Special Report on Emissions Scenarios

Baseline (1960-1990)2020LO2020HI2050LO2050HI

LARS-Weather Generator

Semenov Agric. For. Met. 2000

• Combined climate &crop models

• Yields greatest inScotland

1980s 2050s High CO2

Butterworth et al., 2010, J. Roy. Soc Interface 7, 123-130

Climate change predicted to increase yields of

winter oilseed rape (if disease controlled),

especially in Scotland

Phoma stem canker of oilseed rape

UK losses £180 M; most severe in South

Weather-based forecast of risk of severe stem canker epidemics

Growth along leaf

petiole to produce

stem base canker

in spring

Increase in severity of

phoma stem canker

until harvest (summer)

Ascospore maturation and release;

infection of leaves in autumn

Summer Autumn

Spring Winter

Forecast date

1st leaf spotting

Forecast date

1st canker

Forecast canker severity

Evans et al., 2008, J. Roy. Soc Int. 5, 525-31

13-16 Sep

23-25 Sep

28-30 Sep

01-03 Oct

04-06 Oct

07-10 Oct

11-13 Oct

14-16 Oct

17-19 Oct

20-23 Oct

27 Oct

Forecast dates (10% plants with phoma leaf spot)

2010/2011 winter oilseed rape growing season

http://www.rothamsted.ac.uk/leafspot/

Stonard et al., 2010, Eur. J. Plant Path. 126, 97-109

• Combined climate &

yield loss models

• Yields

(susceptible cultivars)

in England will halve

Hi1980sgh2050s High

Climate change predicted to halve yields in

England without disease control, due to

increasing severity of phoma stem canker

CO2

Butterworth et al., 2010, J. Roy. Soc Interface 7, 123-130

Autumn

Summer Spring

Winter

Air-borne ascospores Phoma leaf spots

Infection

Damage

R gene resistance

Quantitativeresistance

Quantitativeresistance

Early phoma canker

Severe canker (harvest)

Time of RL resistance rating

Climate change & Brassica resistance to L. maculans

Fitt et al., 2006, Eur. J. Plant Path. 114, 3-15

Major gene Rlm6 mediated resistance to

L. maculans is temperature-sensitive

Cultivar

DarmorDarmorMX (Rlm6)

25°C

15°C

Near-isogenic-lines (INRA Rennes)

16 days

post inoculation

Huang et al., 2006, New Phytologist 170, 129-141

Resistant

Susceptible

DarmorMX (Rlm6)

15°C

36 days

after leaf

inoculation

Darmor

25°C

30 days

after leaf

inoculation

Effects of temperature on Rlm6 resistance to L. maculans

(leaves inoculated with conidia of GFP AvrLm6)

L.maculans

labelled with

Green Fluorescent

Protein(Eckert et al., 2005, FEMS

Microbiol. Lett. 253, 67-74)

Temperature effects on quantitative resistance(CE experiments)

Darmor (with quantitative resistance)

Eurol (without quantitative resistance)

Huang et al., 2009, Plant Pathology, 58, 314-323

0

20

40

60

80

100

15 °C 25 °C

Ste

m c

an

ker

severi

ty

(% a

rea a

ffecte

d)

Darmor

Eurol

Disease control - crop resistance, e.g. against Leptosphaeria

maculans (phoma stem canker of oilseed rape)

Resistant crop Susceptible crop

R gene no longer effective

(pathogen had changed)

90% yield loss

Most severe stem canker epidemics in Australia (Mediterranean climate, photos Steve Marcroft)

Canker - global crop losses >£1200 M annually, despite crop protection

Leptosphaeria maculans genome paper published

• Rouxel et al. Nature Communications (Feb 2011)

• L. maculans ‘brassicae’ genome size 45.12 Mb

• 17-18 chromosomes

• Avr (effector) genes often in regions with many transposons

Improve understanding of major gene resistance to

L.maculans

Brassica napus –

Resistance (R) genes*:

Rlm1

Rlm4/Rlm7

Rlm6

L. maculans – Corresponding Avr genes:

Avrlm1+

Avrlm4/7+

Avrlm6+

x*12 Rlm resistance

genes reported to date+ recently clonedby INRA

Air sampling to determine pathogen races

0

20

40

60

80

AvrLm1 AvrLm6

All

ele

fre

qu

en

cy

(%

)

2006/07

2007/08

2008/09

b

Advantages; samples larger population, quicker, cheaper, less laborious than cotyledon assays

Van de Wouw et al., 2010

1. Adaptation; preparing for effects of climate

change on crop diseases - conclusions

• Predict increase in OSR yield if diseasecontrolled; need disease resistance thatoperates at higher temperatures

• Predictions can guide government/industryforward planning by identifying diseases that willbecome more important to ensure future foodsecurity

2. Spread; Phoma stem canker;

two co-existing pathogens & two diseases

L.maculans

L.biglobosa

Upper stem

lesion

Stem base canker

Data from A Dimaghani & B Howlett

L.b. brassicae

L.b. canadensis

L.b. occiaustralensis

L.b. australensis

Europe

Middle EastAsia

PacificIslands

Australia

SouthAmerica

CentralAmerica

NorthAmerica

Africa

Georgia

Chile

China

Canada

Worldwide distribution of L. biglobosa sub-species

Dilmaghani et al., 2009; Van der Wouw et al., 2008

A

B

A/B

1975-98

2001`

1994-2007

Lm

Lb

Lm +

Lb

L. maculans spreading into areas colonised by L. biglobosa

•Before 1975: only L. biglobosa in Canada

•1975: L. maculans in Saskatchewan

•1983: L. maculans in Alberta (Lloydminster)

•1984-1998: spread west across Alberta

Leptosphaeria maculans spread into Canada (Alberta)

Disease control strategies used in Alberta

• Survey to monitor spread of Leptosphaeriamaculans

• Regulatory: Alberta Pests Act 1984 required clean seed, allowed destruction of crop

• Cultural: mandatory crop rotation 1 crop in 4

• Technology transfer / education –

Training farmers/advisors to recognize, control phoma stem canker

• Intended to delay spread of Leptosphaeriamaculans until resistant cultivars became available

Short-term strategyDestruction of crops with L. maculans

Short-term strategyPhoma stem canker survey (Alberta)

• 1983-1998

• 950 crops per year

• 50 plants per crop

• Lab diagnostics

• 4500 data points for modelling

Modelling westward spread of L.maculans across Alberta

1989

Longitude

2 4 6 8 10 12 14 16 18 20 22 24 26 28

La

titu

de

2

4

6

8

10

12

14

16

18

20

22

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1992

Longitude

2 4 6 8 10 12 14 16 18 20 22 24 26 28

La

titu

de

2

4

6

8

10

12

14

16

18

20

22

0.0

0.2

0.4

0.6

0.8

1.0

1995

Longitude

2 4 6 8 10 12 14 16 18 20 22 24 26 28

La

titu

de

2

4

6

8

10

12

14

16

18

20

22

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1998

Longitude

2 4 6 8 10 12 14 16 18 20 22 24 26 28

La

titu

de

2

4

6

8

10

12

14

16

18

20

22

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Latitu

de

Longitude

1989

19981995

1992

(including phoma stem canker disease nursery)

Long-term strategy: Breeding disease resistance

SusceptibleWestar

More resistant

1994

Resistant cultivars became available 1988 – 1995

2. Spread; conclusions

Canadian example can provide lessons for others

● Combination of short-term strategies to decrease spread of L. maculans with long-term strategies

● Short-term; survey, regulation, crop management

● Long-term; resistance breeding; fungicide development

• Agricultural GHG account for 7% of UK total emissions

• The UK target for agriculture in England is to cut GHG

by 3Mt CO2 by 2020.

“... a sustainable

and secure food

system for 2030 ...”

launched 2010

3. Mitigation – can crop disease control contribute?

Mahmuti et al. Int J Agr Sust 7, 189-202 (2009)

0 200 400 600 800 1000 1200 1400 1600

Kg CO2 eq. ha-1

Most GHG to produce 1 ha winter oilseed rape

associated with Nitrogen fertiliser

Fungicides

Herbicides

Insecticides

Lime

P2O5

K2O

N2O (soil)

N

Seed

Field Operations

(manufacture)

(emissions)

600

800

1000

1200

2005 2006 2007 2005 2006 2007

kg

CO

2 e

q.

t-1

untreated

treated

Rothamsted ADAS

Phoma canker

Light leaf spot

ADAS sites were Teversham (2005) and Boxworth (2006-2007)

Treatment with fungicide to control diseases decreases GHG emissions

per tonne seed winter oilseed rape

Fungicides to control disease increase yield & decrease GHG emissions

(in UK wheat, oilseed rape, and barley)

winter wheat winter OSR winter barley spring barley

• Disease control with fungicides or crop resistance decreases GHG emissions

• These GHG reductions contribute to UK targets

3. Mitigation; disease control to combat

climate change - conclusions

Hughes et al., Pest Management Science, 2011, pub-on-line

Crop diseases and climate change

1. Need information to guide strategies for

adaptation to impacts of climate change on crop

diseases losses

2. Need publicity to show how improved crop

disease control can contribute to climate change

mitigation

3. Need vigilance to maintain/improve crop disease

control despite changing pathogen/climate to

ensure global food security

ThanksPlant-pathogen-climate interactions group, Rothamsted

Other contributors to work

• Mike Butterworth

• Regine Delourme et al., INRA

• Maria Eckert

• Simon Edwards, HAUC

• Graham King

• Martin Mahmuti

• Steve Marcroft (Aus. photos)

• Eric Ober

• Thierry Rouxel et al., INRA

• Pierre Stratonovitch

• Sue Welham

Funding

• Modelling – BBSRC;

PASSWORD project; HGCA

and partners/Defra LINK

• Climate change – BBSRC

ISPG, CLIMDIS/OREGIN

projects;Defra

Andreas BaierlMikhail SemenovRodger White