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Management of Management of ClubrootClubroot
S.F. HwangS.F. Hwang 11,S.E. Strelkov,S.E. Strelkov
B.D. GossenB.D. Gossen 33
R.J. HowardR.J. Howard 11R.J. HowardR.J. Howard 11
11Alberta Agriculture and Rural DevelopmentAlberta Agriculture and Rural Development22University of AlbertaUniversity of Alberta33Agriculture and Agriculture and AgriAgri-- Food Canada, SaskatoonFood Canada, Saskatoon
2012 Clubroot Summit, March 7, 20122012 Clubroot Summit, March 7, 2012
ClubrootClubroot in Canolain Canola
,S.E. Strelkov,S.E. Strelkov 22, ,
33, G. Peng, G. Peng3 3 andand
1111
Alberta Agriculture and Rural DevelopmentAlberta Agriculture and Rural Development
Food Canada, SaskatoonFood Canada, Saskatoon
2012 Clubroot Summit, March 7, 20122012 Clubroot Summit, March 7, 2012
1. Establishment of a consortium field nursery1. Establishment of a consortium field nursery
Establishment of a consortium field nursery in 2010
� 9.6 kg of clubroot galls were ground in a blender, the spores were suspended in water (concentration)� Canola ( Female Parent A Sterile Seedalong with clubroot spores over about 3 ha of the s ite in along with clubroot spores over about 3 ha of the s ite in June. � Irrigation line is in place to encourage disease development. �2, 4-D mixed with Roundup the growth of the plants� Plants were cut and worked into the soil in
Establishment of a consortium field nursery in 2010-2011
of clubroot galls were ground in a blender, the spores were suspended in water ( 108 spores/mL
Parent A Sterile Seed ) were planted along with clubroot spores over about 3 ha of the s ite in along with clubroot spores over about 3 ha of the s ite in
Irrigation line is in place to encourage disease
D mixed with Roundup was sprayed in Oct. to stop
and worked into the soil in Nov.
Canola (Female Parent A Sterile Seed) were planted in 2010 and 2011.
Canola (Female Parent A Sterile Seed) were planted in 2010 and 2011.
Derek’s nightmare in 2007!
George’s dream comes true in 2010!
High- Tech harvesting in 2010Tech harvesting in 2010
The inoculum level were tested at several sites throughout the field to ensure even distribution.
The inoculum level were tested at several sites throughout the field to ensure even distribution.
2. Industry representatives visited the nursery at various times throughout the summer.2. Industry representatives visited the nursery at various times throughout the summer.
3. Field testing Edmonton, 20103. Field testing –Edmonton, 2010-11
4. Soil treatments and amendments for amelioration of clubroot of canola
by
S. F. Hwang, S. E. Strelkov, S. F. Hwang, S. E. Strelkov,
B. D. Gossen, G. D. Turnbull, H.U. Ahmed
and V.P. ManoliiCan. J. Plant Sci. (2011) 91: 999
4. Soil treatments and amendments for amelioration of clubroot of canola
by
S. F. Hwang, S. E. Strelkov, S. F. Hwang, S. E. Strelkov,
B. D. Gossen, G. D. Turnbull, H.U. Ahmed
and V.P. ManoliiCan. J. Plant Sci. (2011) 91: 999 -1010.
Seeding and equipment sanitation 2007- 2008equipment sanitation
Effects of chemical soil treatments on canola plant s in clubroot- infested soil
CaCN2 Terraclor
Effects of chemical soil treatments on canola plant s infested soil – Leduc, 2007
Ranman
Effects of soil amendments on canola plants in clubroot- infested soil
Wood ash7.5 t/ha
Effects of soil amendments on canola plants infested soil – Leduc, 2008
Control
Conclusions 2007
•Soil amendments such as wood ash , applied at 7.5 t/ha or more reduce the severity of clubroot and improve yield.•As a chemical soil treatment, 90 kg/ha reduces the severity of clubroot, 90 kg/ha reduces the severity of clubroot, promotes growth, and improves yield. (At 90 kg/ha it costs $1100/ac).
Conclusions 2007 -08:
Soil amendments such as calcium carbonate and , applied at 7.5 t/ha or more reduce the
severity of clubroot and improve yield.As a chemical soil treatment, Terraclor applied at
reduces the severity of clubroot, reduces the severity of clubroot, promotes growth, and improves yield. (At 90 kg/ha
Wood ash 2009-2010 Field Trials• Locations: •Five soil treatments row :
•Terraclor (6.7 kg/ha)•Calcium Carbonate (CaCO
Calcium carbonate
•Calcium Carbonate (CaCO, 67 kg/ha)•Wood ash (WA, 67 kg/ha)•Terraclor + CaCO
•Randomized Complete Block, 4 replicates
2010 Field TrialsLocations: Leduc & EdmontonFive soil treatments applied in-
Terraclor (6.7 kg/ha)Calcium Carbonate (CaCO 3Calcium Carbonate (CaCO 3
, 67 kg/ha)Wood ash (WA, 67 kg/ha)Terraclor + CaCO 3 or WA
Randomized Complete Block, 4 replicates
1.5
2
2.5
Seed
yield
(t/ha
)
Edmonton 2009 Edmonton 2010
Effects of soil treatments on seed yield of canola in clubroot
0
0.5
1
Untreated Terraclor Calcium carbonate
Seed
yield
(t/ha
)
Edmonton 2010 Leduc 2010
Effects of soil treatments on seed yield of canola in clubroot – infested soil
Wood ash Terraclor +Calcium carbonate
Terraclor + wood ash
5. Effects of seed treatments on disease severity and yield of canola in clubroot
infested soils 2009 RCBD near Leduc and Edmonton
�Helix Xtra (difenconazole + fludioxonil)�SYN 524�SYN 524�Dynasty (azoxystrobin)�Helix Xtra+SYN 524�Helix Xtra+Dynasty�Helix Xtra+SYN 524+Dynasty�Non-treated control
5. Effects of seed treatments on disease severity and yield of canola in clubroot
infested soils 2009 – 2010RCBD near Leduc and Edmonton
(difenconazole + fludioxonil)
Helix Xtra+SYN 524+Dynasty
Effects of seed treatments on emergence of canola in clubroot – infested soil in 2010
30
40
50
60
Seed
ling e
merge
nce (
plants
/m2 ) a a
b
0
10
20
30
Untreated Helix XTRA SYN 524Seed
ling e
merge
nce (
plants
/mEffects of seed treatments on emergence of canola in
infested soil in 2010a
b
b
b
Dynasty Helix XTRA + SYN 524
Helix XTRA + Dynasty
Helix XTRA + Dynasty + SYN 524
Effects of seed treatments on seed yield of canola in clubroot
1.5
2
2.5
Seed
yield
(t/ha
)
2009
a a
b
0
0.5
1
Untreated Helix XTRA SYN 524 Dynasty
Seed
yield
(t/ha
)
c ab bca
Effects of seed treatments on seed yield of canola in clubroot – infested soil
2010
a a a a
Dynasty Helix XTRA + SYN 524
Helix XTRA + Dynasty
Helix XTRA + SYN 524 +
Dynasty
bcabc abc
Conclusions:
•In-row application of lime, wood ash or Terraclor did not affect seed yield . •Helix Xtra and Dynasty improved yield over the control in 2009.control in 2009.•Helix Xtra, SYN 524 and Helix Xtra + SYN 524 +Dynasty improved emergence control•All of the seed treatments improved yield the control in 2010
Conclusions:
lime, wood ash or Terraclor .
Helix Xtra and Dynasty improved yield over the
Helix Xtra, SYN 524 and Helix Xtra + SYN 524 improved emergence compared to the
seed treatments improved yield over
6. Seedling age and inoculum density affect clubroot severity and seed yield in canola
by
S. F. Hwang, H. U. Ahmed, S. E. Strelkov,
B. D. Gossen, G. D. Turnbull, G. Peng
and R. J. Howard
Can. J. Plant Sci. 2011. 91: 183
6. Seedling age and inoculum density affect clubroot severity and seed yield in canola
by
S. F. Hwang, H. U. Ahmed, S. E. Strelkov,
B. D. Gossen, G. D. Turnbull, G. Peng
and R. J. Howard
Can. J. Plant Sci. 2011. 91: 183 -190.
Introduction
- Plant disease development is regulatedby the dynamic interaction the pathogen, and the environment. the pathogen, and the environment. - There is little or no data available regarding the impact of density and seedling age disease development.
Introduction
development is regulateddynamic interaction of the host,
the pathogen, and the environment. the pathogen, and the environment. There is little or no data available
regarding the impact of inoculum seedling age on clubroot
disease development.
Effect of seedling age (0clubroot disease severity and plant height
Control
Effect of seedling age (0 -4 wks) on clubroot disease severity and plant height
Inoculated
1.5
2
2.5
Dis
ease
sev
erity
(0-
3)
Effect of seedling age on clubroot disease severity under greenhouse conditions
aa
0
0.5
1
1.5
0 days 1 week
Seedling age
Dis
ease
sev
erity
(0-
3)
Effect of seedling age on clubroot disease severity under greenhouse conditions
b
2 weeks 3 weeks 4 weeks
Seedling age
c c
Effects of inoculum density (0naturally clubroot- infested soilEffects of inoculum density (0 -50%) -
infested soil
0
10
20
30
40
50
60
Pla
nt h
eigh
t (cm
)
y = -0.5888x + 58.356
R2= 0.8960
2.5
3
Dis
ease
sev
erity
(0-
3)
0
0.5
1
1.5
2
2.5
0 10 20 30 40 50 60
Dis
ease
sev
erity
(0-
3)
y = 0.9123 Ln(x) -0.4723
R2= 0.9754
Inoculum density (%)
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40 50 60
See
d yi
eld
(g/p
lant
)
y = -0.6867 Ln(x) +2.5783
R2= 0.8887
Inoculum density (%)
Effect of clubroot inoculum concentration on disease severity, plant height and seed yield in clubroot-infested soil (0 - 50%) under greenhouse conditions
Effect of clubroot severity on plant height and seed yield of canola in
clubroot- infested soil
y = -5.9762x2 + 9.4762x + 55.30680
Pla
nt h
eigh
t (cm
) y = -5.9762x + 9.4762x + 55.306
R2 = 0.8616
0
20
40
60
0 1 2 3 4
Disease severity (0-3)
Pla
nt h
eigh
t (cm
)
Effect of clubroot severity on plant height and seed yield of canola in
infested soil
2
3y = 0.1305x2 - 1.1526x + 2.3885
R2 = 0.9754
0
0.51
1.5
22.5
0 1 2 3 4
Disease severity (0-3 scale)
See
d yi
eld
(g)
Effects of inoculum density infested soil
Effects of inoculum density - Gall-infested soil
0
10
20
30
40
50
60
Pla
nt h
eigh
t (cm
)
y = -0.6629 Ln(x 2) + 1.5038 Ln(x) + 64.028
R2= 0.9853
3
Dis
ease
sev
erity
(0-
3)
0
0.5
1
1.5
2
2.5
3
0.00 2.00 4.00 6.00 8.00 10.00
Dis
ease
sev
erity
(0-
3)
y = 0.3792 Ln(x) + 0.044
R2= 0.9964
Log number of resting spores/mL soil mix
0
0.5
1
1.5
2
2.5
3
0.00 2.00 4.00 6.00 8.00 10.00
See
d yi
eld
(g/p
lant
) y = 0.0381 Ln(x 2) - 0.6952 Ln(x) + 3.1436
R2= 0.9991
Log number of resting spores/mL soil mix
Effect of clubroot spore populations on disease
severity, plant height and seed yield in gall-
infested soil under greenhouse conditions
10.00
Effect of clubroot severity on plant height and seed yield of canola in soil
inoculated with
y = -5.8591x2 + 7.5276x + 63.98
R2 = 0.981360
80
Pla
nt h
eigh
t (cm
)
0
20
40
0 1 2 3
Disease severity (0-3 scale)
Pla
nt h
eigh
t (cm
)
Effect of clubroot severity on plant height and seed yield of canola in soil
inoculated with root galls
y = 0.2102x2 - 1.6752x + 3.1436
R2 = 0.9983
4
See
d yi
eld
(g)/
plan
t
R = 0.998
0
1
2
0 1 2 3 4
Disease severity
See
d yi
eld
(g)/
plan
t
Conclusions• Clubroot severity increased and plant height
and seed yield decreased withinoculum density.
• The young seedlings had severity, shorter plants and lower yield than severity, shorter plants and lower yield than inoculation of older seedlings.
• These results indicate that with a long residual period may be useful for management of clubroot.
ConclusionsClubroot severity increased and plant height and seed yield decreased with increasing
had higher clubroot severity, shorter plants and lower yield than severity, shorter plants and lower yield than inoculation of older seedlings.
indicate that seed treatments with a long residual period (4 weeks or more)
for management of clubroot.
7. Assessment of bait crops to reduce inoculum of clubroot (
brassicae) of canolaby
H.U. Ahmed, S. F. Hwang, S. E. Strelkov,
B. D. Gossen, G. Peng,
R.J. Howard and G. D. TurnbullCan. J. Plant Sci. (2011) 91: 545
7. Assessment of bait crops to reduce inoculum of clubroot ( Plasmodiophora
) of canolaby
H.U. Ahmed, S. F. Hwang, S. E. Strelkov,
B. D. Gossen, G. Peng,
R.J. Howard and G. D. TurnbullCan. J. Plant Sci. (2011) 91: 545 -551.
Introduction
� Use bait crop as a component of an integrated clubroot management program.�A crop that stimulates resting spore �A crop that stimulates resting spore germination could be planted and then ploughed down beforecompletes its life cycleresting spore populations infested fields.
Introduction
as a component of an integrated clubroot management
stimulates resting spore stimulates resting spore could be planted and then
ploughed down before the pathogen completes its life cycle , thereby reducing resting spore populations in heavily
Conclusions
� Both host and non- host crops reduced clubroot incidence in greenhouse studies.
�Bait crops did not reduce spore �Bait crops did not reduce spore populations or clubroot severity studies.
�Use of bait crops is unlikelyimportant component of an IPM program for clubroot of canola.
Conclusions
host crops reduced clubroot incidence in greenhouse studies.
not reduce spore not reduce spore clubroot severity in field
unlikely to be an important component of an IPM program for clubroot of canola.
8. Infection of canola by zoospores of P. brassicae
nonhostBy
J. Feng, Q. Xiao, S.F. Hwang, J. Feng, Q. Xiao, S.F. Hwang,
S.E. Strelkov and B.D. GossenEur. J. Plant Pathol.
DOI 10.1007/s10658
8. Infection of canola by secondary P. brassicae produced on a
nonhostBy
J. Feng, Q. Xiao, S.F. Hwang, J. Feng, Q. Xiao, S.F. Hwang,
S.E. Strelkov and B.D. GossenEur. J. Plant Pathol.
DOI 10.1007/s10658-011-9875-2
Dr. J. Feng
Causal agent:
Kageyama and Asano 2009
Causal agent: P. brassicae
37Kageyama and Asano 2009
Secondary Zoospore Cross Infection Study
�Canola inoculated by 2
o from canola CC
o from ryegrass Co from ryegrass C
� Ryegrass inoculated by spore produced
o from canola RC
o from ryegrass R
Secondary Zoospore Cross Infection Study
inoculated by 2 nd spore produced
C
CRCR
inoculated by spore produced
C
RR
Primary and secondary infectionafter inoculation with secondaryzoospores
infection of ryegrass - 5 dayszoosporesfrom canola.
10 µm
Secondary infection on ryegrass with secondary zoospores from ryegrass
Secondary plasmodia
Secondary infection on ryegrass – 35 days after inoculation ryegrass. Bar = 10 µm.
Conclusions• Secondary zoospores
nonhost can infect a • Secondary infection
nonhost plant species.nonhost plant species.• Pb can proliferate by
hairs prior to secondary infection.
• Resistance to secondary infection in ryegrass is inducedinfection.
ConclusionsSecondary zoospores produced on a
can infect a host species.Secondary infection can occur in a
plant species.plant species.can proliferate by cycling within root
prior to secondary infection.
to secondary infection in induced during primary
42
9. Effects of Seeding Date and Cultivar Resistance on Clubroot Severity, Seedling
Emergence and Yield of Canola
By By
S.F. Hwang, T. Cao, Q. Xiao, H.U. Ahmed, V.P. Manolii, G.D. Turnbull, B.D. Gossen, G. Peng and
S.E. Strelkov,
Can. J. Plant Sci. 2012 (in press)
9. Effects of Seeding Date and Cultivar Resistance on Clubroot Severity, Seedling
Emergence and Yield of Canola
By By
S.F. Hwang, T. Cao, Q. Xiao, H.U. Ahmed, V.P. Manolii, G.D. Turnbull, B.D. Gossen, G. Peng and
S.E. Strelkov,
Can. J. Plant Sci. 2012 (in press)
Field Studies - Interacting effects of seeding date and cultivar resistance
(2010
� Canola cultivars 45H26 (S)(R) serve as main plots
� Seeding dates (Early, Mid, Late) in � Seeding dates (Early, Mid, Late) in plots
�Plots were assessed for emergence, clubroot severity, yield and gall weight
Interacting effects of seeding date and cultivar resistance
(2010-11)
45H26 (S) and 45H29 main plots
(Early, Mid, Late) in sub -(Early, Mid, Late) in sub -
Plots were assessed for emergence, clubroot severity, yield and gall weight
Effects of seeding dates on emergence and seed yield of canola in clubroot
5060708090
100
Emerg
ence
(Plan
ts/m2
)
a
AA
01020304050
Early Mid
Emerg
ence
(Plan
ts/m
Seeding Date
b
Effects of seeding dates on emergence and seed yield of canola in clubroot – infested soil
1.5
2
2.5
3
Yield
(t/ha
)
EmergenceYield
a B
0
0.5
1
1.5
Mid Late
Yield
(t/ha
)
Date - Edmonton
Effects of seeding dates on clubroot severity on canola in clubroot
1.5
2
2.5
3
Seve
rity (
0-3) a
A
A
0
0.5
1
1.5
Early Mid
Seve
rity (
0
Seeding
bA
Effects of seeding dates on clubroot severity on canola in clubroot – infested soil
8
10
12
14
Gall W
eight
(g)
SeverityGall Weight
ab
A
0
2
4
6
Mid Late
Gall W
eight
(g)
Seeding Date - Edmonton
ab
Effects of seeding dates on emergence and seed yield of canola in clubroot
5060708090
100
Emerg
ence
(Plan
ts/m2
)
ba
A
B
01020304050
Early Mid
Emerg
ence
(Plan
ts/m
Seeding Date
Effects of seeding dates on emergence and seed yield of canola in clubroot – infested soil
2.533.544.5
Yield
(t/ha
)
Emergence Yield
00.511.522.5
Mid Late
Yield
(t/ha
)
Date - Leduc
cC
0.81
1.21.4
Seve
rity (
0-3)
Effects of seeding dates on clubroot severity on canola in clubroot
00.20.40.60.8
Early Mid
Seve
rity (
0
Seeding Date
aa
AA
1.5
2
2.5
3
Gall W
eight
(g)
SeverityGall Weight
A
Effects of seeding dates on clubroot severity on canola in clubroot – infested soil
0
0.5
1
1.5
Mid Late
Gall W
eight
(g)
Seeding Date - Leduc
a
1.5
2
2.5
0.81
1.21.4
Gall w
eight
(g)
Seve
rity (
0-3)
SeverityGall Weight
aA
Effects of cultivar resistance on clubroot severity on canola in clubroot
0
0.5
1
00.20.40.6
Resistant Susceptible
Gall w
eight
(g)
Seve
rity (
0
Cultivar - Leduc
b B
810121416
1.5
2
2.5
3
Gall w
eight
(g)
Seve
rity (
0-3)
SeverityGall Weight a
A
Effects of cultivar resistance on clubroot severity on canola in clubroot – infested soil
0246
0
0.5
1
Resistant Susceptible
Gall w
eight
(g)
Seve
rity (
0Cultivar - Edmonton
b B
2.5
3
3.5
4
50
60
70
80
Yield
(t/ha
)
Emerg
ence
(plan
ts/m2
)
EmergenceSeed Yield
aa A
B
Effects of cultivar resistance on emergence and yield of canola in clubroot
0
0.5
1
1.5
2
2.5
0
10
20
30
40
50
Resistant Susceptible
Yield
(t/ha
)
Emerg
ence
(plan
ts/m
Cultivar - Leduc
B
Yield
(t/ha
) 33.54
40
50
60
Yield
(t/ha
)
Emerg
ence
(plan
ts/m2
)
EmergenceSeed Yield
aa
A
Effects of cultivar resistance on emergence and yield of canola in clubroot – infested soil
Yield
(t/ha
)
00.511.522.5
0
10
20
30
Resistant Susceptible
Yield
(t/ha
)
Emerg
ence
(plan
ts/m
Cultivar - Edmonton
B
Cultivar Effect on Clubroot 2010
45H29 (R)
Cultivar Effect on Clubroot -
45H29 (R) 45H26 (S)
Cultivar Effect on Clubroot
45H29 (R)
Cultivar Effect on Clubroot - 2011
45H26 (S)
Cultivar Effect on Clubroot
45H2945H26
Cultivar Effect on Clubroot – Sept. 20, 2011
Late season clubroot galls
Conclusion –• Manipulation of seeding date
clubroot resistant canola cultivars as additional tools in a program
• Younger seedlings suffered • Younger seedlings suffered severity and a greater reduction in plant height and yield than older seedlings in both the resistant and susceptible canola
• Clubroot resistant canola cultivar immune to the disease
Seeding Dateseeding date and the cropping of
resistant canola cultivars can be used additional tools in a clubroot management
suffered greater disease suffered greater disease and a greater reduction in plant height
seedlings in both the resistant and susceptible canola cultivars
resistant canola cultivar 45H29 is not
54
10. Influence of cultivar resistance and inoculum density on
canola by Plasmodiophora brassicae
S.F. Hwang, H.U. Ahmed, Q. Zhou, S.E. Strelkov, B.D. Gossen, G. Peng and G.D. Turnbull
Plant Pathology (2011) 60: 820
10. Influence of cultivar resistance and inoculum density on root hair infection of
by Plasmodiophora brassicae
byby
S.F. Hwang, H.U. Ahmed, Q. Zhou, S.E. Strelkov, B.D. Gossen, G. Peng and G.D. Turnbull
Plant Pathology (2011) 60: 820 -829.
Effects of soil inoculum density on growth, disease and yield of canola
Height Soil Dilutions (cm)Clubroot-Resistant (45H-29)
0:1 (infested soil: soil-less mix)
1:8 (infested soil: soil-less mix)
1:1 (infested soil: soil-less mix)
1:0 (infested soil: soil-less mix)
Mean
Clubroot-Susceptible (45H-26)
0:1 (infested soil: soil-less mix)
1:8 (infested soil: soil-less mix)
1:1 (infested soil: soil-less mix)
1:0 (infested soil: soil-less mix)
Mean
Effects of soil inoculum density on growth, disease and yield of canola
Height Emergence Yield Disease(cm) (%) (g/pot) Index
104 a 72 a 2.79 a 0
94 b 58 a 2.26 ab 0
84 c 54 a 1.77 b 0
92 b 18 b 0.60 c 5.6
94 A 51 A 1.85 A 1.4 B
105 a 72 a 2.67 a 0 c
94 b 42 b 0.78 b 28 b
54 c 28 bc 0.01 c 90 a
40 d 22 c 0.01 c 100 a
73 B 41B 0.86 B 54.5 A
Colonization of canola root hairsColonization of canola root hairs
20
30
40
50
60
% R
oot h
air
colo
nize
d
ResistantSusceptible
b
a
b
a
Effects of soil inoculum level on root hair colonization
% R
oot h
air
colo
niza
tion
0
10
20
11 50 100
% R
oot h
air
colo
nize
d
% Clubroot infested soil (v:v)
a
b
a
% R
oot h
air
colo
niza
tion
Effects of soil inoculum level on root hair colonization
30
40
50
60 Resistant
Susceptiblea
a
0
10
20
1,000 100,000 10,000,000
Spores per mL soil-less mix
b
b ba
30
40
50
60
% R
oot h
air
colo
niza
tion
Resistant
Susceptible
b
aa
a
bbbb
Effects of incubation period on root hair colonization
0
10
20
6 8 10 12 14
% R
oot h
air
colo
niza
tion
Days after seeding
b b
b
bbbb
Naturally infested soil
Effects of incubation period on root hair colonization
30
40
50
60
70
% R
oot h
air
colo
niza
tion
ResistantSusceptible
a
a
a
a
Spores inoculatedin soilless mix (106/g)
0
10
20
30
6 8 10 12 14
% R
oot h
air
colo
niza
tion
Days after seeding
ba
ba
ba
b
60
70
80
90
100
Inde
x of
dis
ease
(%
)Effects of root hair colonization on
disease index of clubroot
0
10
20
30
40
50
0 20 40
Inde
x of
dis
ease
(%
)
Root hair colonization (%)
y=100R2=0.99
Effects of root hair colonization on disease index of clubroot
60 80 100
Root hair colonization (%)
y=100-(0.392e)-90x
=0.99
11. Root Hair Colonization of Resistant and Susceptible Canola by
brassicae
By By
S.F. Hwang, H.U. Ahmed, Q. Zhou, S.E. Strelkov, B.D. Gossen, G. Peng, and G.D. Turnbull
Plant Pathology 2012(Doi: 10.1111/j.1365
11. Root Hair Colonization of Resistant and Susceptible Canola by Plasmodiophora
brassicae
By By
S.F. Hwang, H.U. Ahmed, Q. Zhou, S.E. Strelkov, B.D. Gossen, G. Peng, and G.D. Turnbull
Plant Pathology 2012(Doi: 10.1111/j.1365-3059.2011.02582.x)
• To examine the relationship between root hair infection and P. brassicadetected by q PCR.
Objective:
detected by q PCR.
relationship between root P. brassica DNA
Objective:
40
50
60
70
80
Index
of di
seas
e (%)
Effect of cultivar resistance on the index of disease in five canola cultivars
0
10
20
30
40
45H29 73-77RR
Index
of di
seas
e (%)
cc
a a
b
Effect of cultivar resistance on the index of disease in five canola cultivars
45H26 34-65RR 45H73Cultivar
Comparison of bioassay and qPCR analysis
•Five canola cultivars , 45H29, 45H26, 7334-65RR, and 45H73 were planted in cups.
• Each cultivar was sampled at 4, 6, 8, and 10 days after sowing.
• Half of the plants were fixed in hair analysis ; half were stored for analysis .
• Weight of P. brassicae using qPCR analysis.
Comparison of bioassay and qPCR analysis
, 45H29, 45H26, 73-77RR, 65RR, and 45H73 were planted in cups.
sampled at 4, 6, 8, and 10
Half of the plants were fixed in FAA for root ; half were stored for qPCR
P. brassicae DNA was estimated
25
30
35
40
45
50
% R
oot h
air
colo
niza
tion
aa
a aa a
b
Root hair colonization in five canola cultivars gro wn in clubroot- infested soil
0
5
10
15
20
4 days 6 days
% R
oot h
air
colo
niza
tion
Days after seeding
b b b bb
45H29
73-77RR
45H26
a
b bb b
a
a
a
aa
Root hair colonization in five canola cultivars gro wn infested soil
8 days 10 days
Days after seeding
45H26
34-65RR
45H73
b bb b
15
20
25
30
35
Am
ount
of D
NA
(ng
µL
-1)
aaa b
P. Brassicae DNA found in five canola cultivars grown in clubroot
0
5
10
15
4 days 6 days
Am
ount
of D
NA
(ng
Days after seeding
a aaaa
aa
bb
b
45H29
73-77RR
45H26cb
ab
a
b
aab
c
DNA found in five canola cultivars grown in clubroot -infested soil
8 days 10 days
Days after seeding
45H26
34-65RR
45H73
cb c
y = 2.8853x - 41.027r² = 0.93
0
5
10
15
20
25
30
35
10 12 14 16 18 20
Am
ount
of D
NA
(ng
µL
-1)
45H29
y = 2.3116x r² = 0.81
0
5
10
15
20
25
30
35
10 12 14
Am
ount
of D
NA
(ng
µL
-1)
% Root hair colonized
73-77RR
Relationship between amount of and root hair colonization in
% Root hair colonized% Root hair colonized
y = 1.1247x - 20.231r² = 0.76
0
5
10
15
20
25
30
15 25 35 45
Am
ount
of D
NA
(ng
µL
-1)
%Root hair colonized
45H26
y = 0.9871x r² = 0.73
0
5
10
15
20
25
30
35
15 25
Am
ount
of D
NA
(ng
µL
-1)
%Root hair colonized
34-65RR
Susceptible cultivars
y = 2.3116x - 28.485r² = 0.81
16 18 20% Root hair colonized
Resistant cultivars
Relationship between amount of P. Brassicae DNA and root hair colonization in five canola cultivars
% Root hair colonized
y = 0.9871x - 19.223r² = 0.73
35 45 55
%Root hair colonized
y = 1.0281x - 21.58r² = 0.71
0
5
10
15
20
25
30
10 20 30 40 50
Am
ount
of D
NA
(ng
µL
-1)
%Root hair colonized
45H73
Susceptible cultivars
y = 0.0076x + 0.0247r² = 0.80
0
0.1
0.2
0.3
10 15 20 25 30
Am
ount
of D
NA
(ng
µL
-1)
Day 4
Am
ount
of D
NA
(ng
µL
-1)
P. Brassicae DNA found in canola grown in clubrootinfested soil at four intervals
% Root hair colonized
y = 0.2321x + 8.0729r² = 0.90
0
5
10
15
20
25
10 20 30 40 50
Am
ount
of D
NA
(ng
µL
-1)
% Root hair colonized
Day 8
Am
ount
of D
NA
(ng
µL
-1)
y = 0.5329x - 1.4247r² = 0.82
0
2
4
6
8
10
12
14
16
10 15 20 25 30
Am
ount
of D
NA
(ng
µL
-1)
% Root hair colonized
Day 6
DNA found in canola grown in clubroot -at four intervals after seeding
% Root hair colonized
y = 0.6437x + 0.9555r² = 0.99
0
5
10
15
20
25
30
35
10 20 30 40 50
Am
ount
of D
NA
(ng
µL
-1)
% Root hair colonized
Day 10
y = 0.6944x - 7.1887r² = 0.6388
20
25
30
35
Am
ount
of D
NA
(ng
µL
-1)
Relationship between amount of and root hair colonization in
four sampling dates
0
5
10
15
20
10 15 20 25
Am
ount
of D
NA
(ng
µL
% Root hair colonization
7.1887
Relationship between amount of P. Brassicae DNA and root hair colonization in five canola cultivars at
four sampling dates
30 35 40 45 50
% Root hair colonization
• A strong linear relationship between root hair infection pathogen DNA .
• In susceptible cultivars pathogen DNA rose more sharply
Results:
pathogen DNA rose more sharply resistant cultivars.
• Height of both susceptible and resistant cultivars was reduced after inoculation with the pathogen.
strong linear relationship was found root hair infection and the amount of
susceptible cultivars the amount of DNA rose more sharply than in the
Results:
DNA rose more sharply than in the
Height of both susceptible and resistant cultivars was reduced after inoculation with the
Effects of growing resistant cultivars on spore populations
Widespread release of genetically resistant canola hybrids in 2010
Effects of growing resistant cultivars on spore populations
Widespread release of genetically resistant canola hybrids in 2010
16x109 spores/matured gall
≈ 800x106 spores/g gall, ≈ 20 g/gall of matured plant
spores/matured gall
Root galls release millions of spores into soil
≈ 20 g/gall of matured plant
45H29
45H26
Treatment Resting spore
(g)-1 soil
Resistant cultivar
1.0×108 b
Quantification of P. brassicae by microscopy andqPCR analysis
cultivar
Susceptible cultivar
2.0×108 a
Fallow control9.2×107 c
DNA was extracted from 0.5 g soil after adding macerated gall tissue after the first cycle of cropping
Ct Value DNA (ng) - µL
24.75 a 0.338 b
Quantification of P. brassicae by microscopy andqPCR analysis
20.18 b 6.248 a
25.24 a 0.215 b
DNA was extracted from 0.5 g soil after adding macerated gall tissue
12. Effects of Cropping ClubrootCanola Plants on Plasmodiophora brassicae
Resting Spore Populations in the Soil
By By
S.F. Hwang, H.U. Ahmed, Q. Zhou, A. Rashid, S.E. Strelkov, B.D. Gossen, G. Peng, and G.D. Turnbull
Plant Pathology
12. Effects of Cropping Clubroot-Resistant Canola Plants on Plasmodiophora brassicae
Resting Spore Populations in the Soil
By By
S.F. Hwang, H.U. Ahmed, Q. Zhou, A. Rashid, S.E. Strelkov, B.D. Gossen, G. Peng, and G.D. Turnbull
Plant Pathology 2012 (accepted)
Effects of Cycles of Resistant Canola Lines Clubroot Spore Populations in Infested Soil
Objective:To evaluate the effects of growing the same resistant cultivar growing the same resistant cultivar • Resting spore populations of brassicae• Subsequent severity of clubroot in susceptible canola.
Cycles of Resistant Canola Lines on Clubroot Spore Populations in Infested Soil
To evaluate the effects of repeatedly growing the same resistant cultivar on:growing the same resistant cultivar on:
Resting spore populations of P.
Subsequent severity of clubroot in
• Canola cvs 45H29 (R) and 45H26 (S) inoculated soilless mix. A fallow control (F) • After 4 wk, roots were re-incorporated into the soil.• A new crop (same cultivar) was replanted into the soil.
A. Effects of growing resistant cultivars on clubroot severity in subsequent crops
• Three treatments: RRRS, SSSS, FFFS•Root weight, plant height, clubroot incidence and severity, and resting spore populations were recorded after each cycle.
45H26 (S) were grown in fallow control (F) was added .incorporated into the soil.
A new crop (same cultivar) was replanted into the soil.
A. Effects of growing resistant cultivars on clubroot severity in subsequent crops
RRRS, SSSS, FFFSRoot weight, plant height, clubroot incidence and
severity, and resting spore populations were recorded
30
40
50
60
Plant
heigh
t (cm) a
b
ba
Effect of sequential growth of resistant and susceptible canola cultivars on
0
10
20
R S RR SS
Plant
heigh
t (cm)
Cropping cycles of canola cultivars
c
b
b
a
a
Effect of sequential growth of resistant and susceptible canola cultivars on plant height
RRR SSS RRRS SSSS FFFS
Cropping cycles of canola cultivars
15
20
25
30
35
Fresh
root
weigh
t (g)
ba
a
Effect of sequential growth of resistant and susceptible canola cultivars on
0
5
10
15
R S RR SS
Fresh
root
weigh
t (g)
Cropping cycles of canola cultivars
b
a
a
Effect of sequential growth of resistant and susceptible canola cultivars on root biomass
RRR SSS RRRS SSSS FFFS
Cropping cycles of canola cultivars
b
bb
1.5
2
2.5
Clubro
ot sev
erity
(0-3 s
cale)
a
a
Effect of sequential growth of resistant and susceptible canola cultivars on
0
0.5
1
R S RR SS
Clubro
ot sev
erity
(0
Cropping cycles of canola cultivars
b b
a
aa
Effect of sequential growth of resistant and susceptible canola cultivars on clubroot severity
RRR SSS RRRS SSSS FFFS
Cropping cycles of canola cultivars
bb
b
30
40
50
60
70
Index
of di
seas
e (%)
a
a
Effect of sequential growth of resistant and susceptible canola cultivars on
0
10
20
30
R S RR SS
Index
of di
seas
e (%)
Cropping cycles
bb
aa
Effect of sequential growth of resistant and susceptible canola cultivars on index of disease
RRR SSS RRRS SSSS FFFS
cycles of canola cultivars
bb
b
• Plant height: FFFS>RRRS>SSSS• Greater root mass in the resulted from gall formation.
Results - Effects of growing resistant cultivars on clubroot severity in subsequent crops and resting
spore population
resulted from gall formation.• At the end of fourth cropping cycleseverity on a susceptible canola cultivar grown in the potting mixture was 10compared to the SSSS cropping sequence.•The clubroot severity in FFFS sequence very low compared to the
FFFS>RRRS>SSSSin the susceptible cultivar
resulted from gall formation.
Effects of growing resistant cultivars on clubroot severity in subsequent crops and resting
spore population
resulted from gall formation.end of fourth cropping cycle, the disease on a susceptible canola cultivar grown in
10-fold lower in the RRRS cropping sequence.
FFFS sequence was also compared to the SSSS sequence.
15
20
25
Resti
ng sp
ores x
105 /
g soil
-less
mix
aa
0
5
10
R S F RR SS FF
Resti
ng sp
ores x
10
Cropping cycles of canola cultivars
bb
b
b
a a
RRR SSS FFF RRRS SSSS FFFS
Cropping cycles of canola cultivars
bb
b
b
•The number of resting spores sequence was 5 and 15-the FFFS and RRRS sequences, respectively.
Results - Effects of resistant cultivars on resting spore population
the FFFS and RRRS sequences, respectively.• After each cycle of cropping of susceptible canola (S, SS, SSS and SSSS) the inoculum density gradually increased. • The resting spore density sequence was greater relative to the Resistant or Fallow sequences.
number of resting spores following the SSSS-fold higher than in
sequences, respectively.
Effects of resistant cultivars on resting spore population
sequences, respectively.After each cycle of cropping of susceptible canola
inoculum density
resting spore density in the Susceptible sequence was greater relative to the Resistant or
• 45H29 (R) and 45H26 (S) canola cultivars were grown at 2 sites in heavily infested field soil.
B. Resting spore populations after cropping resistant and susceptible canola
soil.•On August 16, 20 plants per replicate of a cultivar were uprooted and washed•Gall mass and spores per gram of gall tissue were recorded.
45H29 (R) and 45H26 (S) canola cultivars were grown at 2 sites in heavily infested field
B. Resting spore populations after cropping resistant and susceptible canola
, 20 plants per replicate of a cultivar were uprooted and washed
spores per gram of gall tissue
Spore production in resistant and susceptible canola cultivars
2
2.5
3
3.5
Gal
l mas
s (g
)
0
0.5
1
1.5
Resistant Susceptible
Gall mass
Gal
l mas
s (g
)Spore production in resistant and susceptible canola
cultivars
0.6
0.8
1
1.2
Spo
res/
g X
10
10
0
0.2
0.4
0.6
Resistant Susceptible
Spores/g
Spo
res/
g X
10
• The gall mass produced by the susceptible canola cultivar was 14-fold greater resistant canola cultivar.• 14% of 45H29 were infected with clubroot;
Results - Resting spore contribution due to cropping resistant and susceptible canola
• 14% of 45H29 were infected with clubroot; of 45H26 plants were infected.• Galls from the susceptible canola produced spores /g gall while those from the resistant canola produced 0.6 x1010
produced by the susceptible canola fold greater compared to the
were infected with clubroot; 100%
Resting spore contribution due to cropping resistant and susceptible canola
were infected with clubroot; 100% plants were infected.
susceptible canola produced 1010
while those from the resistant 10 spores /g gall.
• Growing susceptible canola resting spores into the soil population than growing the resistant cultivar.•Repeated growing of resistant canola fallowing both reduced resting spore populations in the soil.
Conclusions
in the soil.•However, repeated cultivation of a resistant cultivar may result in selection for pathogen phenotypes that can overcome this source of resistance.• Resistance Stewardship is needed
susceptible canola contributed moreinto the soil population than
growing the resistant cultivar.Repeated growing of resistant canola and
resting spore populations
Conclusions
However, repeated cultivation of a resistant selection for pathogen
that can overcome this source of
Resistance Stewardship is needed.
Acknowledgments
�Graduate students, Research personnel and Collaborators�Canola Council through AAFC Clubroot
Risk Mitigation Initiative�Canola Council through AAFC Clubroot
Risk Mitigation Initiative�Alberta Crop Industry Development Fund�Agriculture & Food Council�ACPC, SaskCanola, MCGA and other
industry partners
Acknowledgments
Graduate students, Research personnel
Canola Council through AAFC Clubroot Risk Mitigation InitiativeCanola Council through AAFC Clubroot Risk Mitigation InitiativeAlberta Crop Industry Development FundAgriculture & Food CouncilACPC, SaskCanola, MCGA and other
Alberta Agriculture Teamwork Recognition Award 2011
Thanks for your attention!
Alberta Agriculture Teamwork Recognition Award 2011
Thanks for your attention!
