The New Zealand Institute for Plant & Food Research Limited

Diseases caused by

Spongospora subterranea implicated

as components of sub-optimum

potato yields in New Zealand

Richard Falloon, Sarah Sinton, Farhat Shah, Steven Dellow,

Alexandre Michel, Craig Tregurtha & Hamish Brown3rd International Powdery Scab Workshop

Einsiedeln, Switzerland, 17-21 July 2014

New Zealand Institute for Plant & Food Research

Acknowledgements

Collaborating researchers:Dr Denis Curtin, Ros Lister, Dr Ruth Butler, Russell Genet,

Dr Mark Paget, Dr Ueli Merz

Plant pathology, Soil science, Agronomy, Plant breeding,

Biometrics

Funding agencies:

NZ Ministry for Business, Innovation and Employment

Potatoes New Zealand

Foundation for Arable Research

NZ Ministry of Agriculture & Fisheries Sustainable Farming Fund

McCain Foods Grower Group

NZ Institute for Plant & Food Research

Trimble Agricultural Research (Travel) Fellowship

• Part 1: Spongospora root diseases (Some history)

(summary of experimental evidence)

• Part 2: Multi-year field evaluations (“Yield gap”)

• Conclusions

Falloon, Merz, et al. (2016).

Plant Pathology 65: 422-434

Part 1: Some history1994: pre-planting fluazinam soil treatment reduced incidence of

powdery scab, increased tuber yield by 28% (weight/tuber)

Total crop yield

+28%(increased weight/tuber)

% diseased

no chemical 19

fluazinam 6

tonnes ha-1

44.7

57.3

Some history1994: pre-planting fluazinam soil treatment reduced incidence of

powdery scab, increased tuber yield by 28% (weight/tuber)

2005: Field-grown potato plants inoculated with S. subterranea had reduced

tuber yields, and reduced water use.

cv. Iwa

Plant parameters at harvest

Mean wgt

(kg) tubers

per plant

Mean no.

tubers per

plant

Mean wgt

(g) per

tuber

No inoculum 2.93 12.1 242

Inoculum 1.70 9.0 188

change -42% -26% -22%

Soil moisture measurementsTime domain reflectometry

Sample Date

7-Nov 21-Nov 5-Dec 19-Dec 2-Jan 16-Jan 30-Jan 13-Feb 27-Feb

Me

an

wa

ter

use

dif

fere

nce

fro

m a

ve

rag

e (

%)

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

� � � � � � � � � �

UninoculatedInoculatedIrrigation�

Rain

Water use

Some history1994: pre-planting fluazinam soil treatment reduced incidence of

powdery scab, increased tuber yield by 28% (weight/tuber)

2005: Field-grown potato plants inoculated with S. subterranea had reduced

tuber yields, and reduced water use.

2011: Greenhouse trial; S. subterranea reduced root function and

growth of eight cultivars, with different susceptibilities to tuber

powdery scab

Glasshouse experiment

• Plant parameters

• Water use

• Spongospora severity

•Eight cultivars uninoculated

or inoculated with S. subterranea

• Very resistant‘Gladiator’, ‘Moonlight’ ‘Red Rascal’

• Moderately resistant‘Russet Burbank’, ‘Ranger Russet’,

‘Umatilla Russet’

• Very susceptible‘Iwa’, ‘Asterix’

Shoot Dry Weight

Gladiat

orMoonlig

htRed

Ras

cal

Ranger

Russ

etRuss

et B

urban

kUm

atilla

Russ

et Iwa

Aster

ix

g

1.21.41.61.82.02.22.42.62.8

V. Resistant Mod. Resistant V. Susceptible

UninoculatedInoculated

Bar is LSD 5%

Plant growth

Root function

Iwa

Days after planting

0 10 20 30 40 50

Wat

er u

se (

g)

0

5

10

15

20

25

↑↑↑↑ Inoculation

Ranger Russet

Days after planting

0 10 20 30 40 50

Wat

er u

se (

g)

0

5

10

15

20

25

↑↑↑↑ Inoculation

Russet Burbank

Days after planting

0 10 20 30 40 50W

ater

use

(g

)0

5

10

15

20

25

↑↑↑↑ Inoculation

Asterix

Days after planting

0 10 20 30 40 50

Wat

er u

se (

g)

0

5

10

15

20

25

↑↑↑↑ Inoculation

un-inoculatedinoculated

Umatilla Russet

Days after planting

0 10 20 30 40 50

Wat

er u

se (

g)

0

5

10

15

20

25

↑↑↑↑ Inoculation

Gladiator

Days after planting

0 10 20 30 40 50

Wat

er u

se (

g)

0

5

10

15

20

25

↑↑↑↑ Inoculation

Moonlight

Days after planting

0 10 20 30 40 50

Wat

er u

se (

g)

0

5

10

15

20

25

↑↑↑↑ Inoculation

Red Rascal

Days after planting

0 10 20 30 40 50

Wat

er u

se (

g)

0

5

10

15

20

25

↑↑↑↑ Inoculation

Final Water Use

Gladiat

orMoonlig

htRed

Ras

cal

Ranger

Russ

etRuss

et B

urban

kUm

atilla

Russ

et Iwa

Aster

ix

g

8

10

12

14

16

18

20

22V. Resistant Mod. Resistant V. Susceptible

UninoculatedInoculated

Bar is LSD 5%

Root function

Root galls

Galls/g Root Dry Weight

Gladiat

orMoonlig

htRed

Ras

cal

Ranger

Russ

etRuss

et B

urban

kUm

atilla

Russ

et Iwa

Aster

ix

Gal

ls/g

50

100

150

200

250

300

350

400

450 V. Resistant Mod. Resistant V. Susceptible

Spongospora root infection

• This pathogen adversely affects host plant

growth and productivity

• Deleterious effects occur, both in tuber-

resistant and tuber-susceptible cultivars

• Disrupted root function, root galling and

tuber powdery scab are separate diseases

Part 2: The “Yield Gap” projects

• Grower initiated

• Potato yields becoming uneconomic

• Average yields 45 to 60 t ha-1

• Potential yields >90 t ha-1

(as shown using validated computer-based

crop growth model)

Multi-year field evaluations

• Three growing seasons:

• 2012/13, 2014/15 and 2015/16

• Multiple crops (processing and fresh market)

• Detailed surveys

• Multiple samplings within each crop

• Assessment of yield-limiting factors

2012/13 - Field survey sites

Four fertiliser trials

No appreciable increase in yield

with doubled rates

11 crops, 10 visits each (≈10 d intervals)(110 crop visits)

diseasedhealthy

Major yield-limiting factors

• Soilborne diseases

• Soil compaction

• Inefficient irrigation

• Weed infestations

• Variable plant emergence

Rhizoctonia stem canker - all 11 crops

Long term cropping,

potatoes 5 years previously

Long term grass,

no history of potatoes

Rhizoctonia stem canker

-30

-25

-20

-15

-10

-5

0

5

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190

He

igh

t fr

om

to

p o

f ri

dg

e (

cm

)

Distance from centre of ridge (cm)

Potato bed profiles - Potato Yield Gap Project

Wheel track on left, bed furrow on right

Site 7

Seed depth

-30

-25

-20

-15

-10

-5

0

5

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190

He

igh

t fr

om

to

p o

f ri

dg

e (

cm

)

Distance from centre of ridge (cm)

Potato bed profiles - Potato Yield Gap Project

Wheel track on left, bed furrow on right

Site 8

Seed depth

Soil compaction

Yield vs root vigour

Spongospora root galls - five crops

Inefficient irrigation

0

10

20

30

40

50

60

70

80

Irrigationmissed

Irrigationnormal

Irrigationmissed

Irrigationnormal

Crop 6 Crop 6 Crop 1 Crop 1

Fre

sh t

ub

er y

ield

(t/

ha)

No irrigation Irrigated

Two crops

Weeds(Solanum spp.)

0

10

20

30

40

50

60

70

80

90

100

weeds weed-free

Crop 11 Crop 11

Fre

sh t

ub

er y

ield

(t/

ha)

One crop

Yield-limiting factors

2012/13 crop yields

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11

Ma

rke

tab

le Y

ield

(t/

ha

)

Site

Potential

Field

2014/15 - Three fields

The New Zealand Institute for Plant & Food Research Limited

Eight sites in each crop

• Soil water measurements

• Regular (3 week intervals) crop sampling

and disease assessments

• Crop yields

The New Zealand Institute for Plant & Food Research Limited

Site 1

Site 1: deep soil, flat field

Soil water content

The New Zealand Institute for Plant & Food Research Limited

Site 2

The New Zealand Institute for Plant & Food Research Limited

Site 2

Site 2: stony soil, dense zone 250 mm, undulating

Soil water content

Site 3

Site 3: two soil types, stony, undulating

Soil water content

Rhizoctonia stem canker

severity score

(5 ≡ 30% coverage)

Site 3

Site 2Site 1

Spongospora root and stem galls

0

2

4

6

8

10

12

14

16

18

20

4-N

ov

-14

21

-No

v-1

4

10

-De

c-1

4

7-J

an

-15

3-F

eb

-15

3-M

ar-

15

10

-No

v-1

4

21

-No

v-1

4

10

-De

c-1

4

7-J

an

-15

2-F

eb

-15

3-M

ar-

15

1-D

ec-

14

23

-De

c-1

4

19

-Ja

n-1

5

17

-Fe

b-1

5

23

-Ma

r-1

5

Perry Pye Tayler

Sp

on

go

spo

raro

ot

ga

lls/

pla

nt

Spongospora (root galls)

Site 3Site 1 Site 2

Site 3: stony soil, Rhizoctonia stem canker,

Spongospora root galls

0

10

20

30

40

50

60

70

80

90

100

8 Oct 28 Oct 17 Nov 7 Dec 27 Dec 16 Jan 5 Feb 25 Feb 17 Mar

Tub

er

fre

sh w

eig

ht

(t/h

a)

Potential

1

2

3

4

5

6

7

8

Plot av

36 t/ha yield loss

2015/16 - 18 fields, 25 ‘crops’(fresh market and processing)

0

2

4

6

8

10

12

14

16

18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Crops

Rhizoctonia stem canker severity

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Crops

Spongospora root gall severity

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Crops

Powdery scab severity

1.0 = 5% tuber surface

affected

Conclusions• Spongospora root diseases reduce potato plant

growth and productivity (Part 1)

• Soilborne diseases are key causes of sub-optimum

potato yields in New Zealand

• Spongospora root diseases are commonly severe in

New Zealand (processing) potato crops

• Spongospora root galling has caused widespread

occurrence of these diseases

• Spongospora diseases are important causes of yield

reductions - effective management urgently required

Other diseases

Rhizoctonia,

black dot, common scab, Sclerotinia

Other yield limiting factors