Sustainability of continuous wheat sequences

in relation to crown rot in the low rainfall

Eastern Wheatbelt

Bob FrenchA and Shahajahan MiyanB

DPIRD AMerredin and BNortham

• Wheat after wheat is common in

WA, especially in low rainfall

areas and on loamy soils

• This is despite the well known

benefits of break crops for

system sustainability

• Can management of continuous

wheat prolong system

sustainability?

BACKGROUND

Where is crown rot in WA? – Stubble

plating survey 2012-2013

Crown rot incidence in

paddocks:

4 National crown rot project

(DAN00175)

Wheat yield loss – met-analysis 2014-2016

05

1015202530354045

Justica C

L

Wyalk

atc

hem

Mage

nta

Mace

Cob

ra

Calin

gir

i

Harp

er

Westo

nia

Yitpi

Cora

ck

Tro

jan

Sce

pte

r

Em

u R

ockYie

ld l

oss t

o c

row

n r

ot

(%)

Yield loss categories

0-10% Low

10-20% Medium

>20% High

Presented at Crop Updates – Feb 2017

Article in GroundCover Soilborne Diseases Supp. 2017

National crown rot project

(DAN00175)

(Huberli et al. Crop Updates 2017)

TRIAL DESIGN

2015 2016 2017 2018

Wheat Wheat Wheat Wheat

Canola Wheat Wheat Wheat

Fallow Wheat Wheat Wheat

Fallow Canola Wheat Wheat

Canola Fallow Wheat Wheat

Wheat Fallow Canola Wheat

2015 2016 2017 2018

Wheat Wheat Wheat Wheat

Canola Wheat Wheat Wheat

Fallow Wheat Wheat Wheat

Fallow Canola Wheat Wheat

Canola Fallow Wheat Wheat

Wheat Fallow Canola Wheat

2015 2016 2017 2018

Wheat Wheat Wheat Wheat

Canola Wheat Wheat Wheat

Fallow Wheat Wheat Wheat

Fallow Canola Wheat Wheat

Canola Fallow Wheat Wheat

Wheat Fallow Canola Wheat

Six sequences

Previous crop did not affect wheat yield in 2016

0

0.5

1

1.5

2

2.5

0.0

0.5

1.0

1.5

2.0

2.5

Gra

in y

ield

(t/

ha)

Emu Rock

Mace

Magenta

Average

Sequence did not affect wheat yield in 2017

0

0.5

1

1.5

2

0.0

0.5

1.0

1.5

2.0

Gra

in y

ield

(t/

ha)

Emu Rock

Mace

Magenta

Average

Initial crown rot levels were high

• In 2015 crown rot organism

isolated from ~12% of crowns

remaining from 2014*

• Predicta B: high levels of crown

rot DNA in soil, low or nil levels

of other soil borne diseases

* GRDC National Crown Rot Project (DAN00175)

Crown rot expression

0

5

10

15

20

25

30

35

40

45

50C

row

n r

ot

seve

rity

Emu Rock

Mace

Magenta

2016 2017

Sequence and cultivar both affect crown rot severity

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Cro

wn

ro

t D

NA

(lo

g(p

g/g

so

il +1

))

Emu Rock

Mace

Magenta

2016 2017

Sequence and cultivar both affect soil crown rot

DNA levels

Soil DNA levels are related to crown rot severity in previous

year

R² = 0.8582

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80 100

20

17

Pre

dic

ta B

2016 crown rot incidence (%)

Magenta

Emu Rock

Mace

Sequence and crop competitiveness affect

ryegrass head numbers

2015 2016 2017

All cropped plots 18

Fallow <1 <1 <1

Canola 14

Wheat after wheat 2 9

Wheat after canola 20

Emu Rock – cont. wheat 45

Emu Rock – after canola 54

Mean ryegrass heads/m² in October 2015

18

<1

2 14

9 20 45

54

• Continuous wheat can be sustainable for at least 4 years on a loamy soil

with a crown rot background

• Emu Rock has lower crown rot expression than Mace or Magenta and

lower inoculum carry-over to the following season.

• Competitive crops are crucial in preventing weed blowouts

CONCLUSIONS

Grains Research and Development Corporation (GRDC)

A Level 4, East Building, 4 National Circuit, Barton, ACT 2600 Australia

P PO Box 5367 Kingston, ACT 2604 Australia

T +61 2 6166 4500

F +61 2 6166 4599

www.grdc.com.au

@thegrdc @GRDCWest #GRDCUpdates

Thank you

Merredin Research facility staff Shahajahan Miyan Bruce Haig Julia Tilli GRDC co-invested in this work as part of project DAW00249