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Analysis of Weather, Microclimate and Canopy Density on Sclerotinia Stem Rot Disease in Canola Reanne Pernerowski 1 , Paul Bullock 2 , Dilantha Fernando 3 Sclerotinia stem rot disease (SSR) in an increasingly important disease in the Canadian prairies creating unpredictable yield losses ranging between 5 and 100 percent in Manitoba. Management is extremely important due to the little commercially available resistant canola varieties. Caused by the fungus Sclerotinia sclerotiorum, sclerotinia begins its life cycle as sclerotia in the soil. Under specific environmental conditions sclerotia germinates and eventually releases ascospores into the surrounding atmosphere. Ascospores land on senescing flower tissue of the canola plant and subsequently land on the leaves and stems and begin to kill the entire plant. Canopy density and weather are important factors known to influence disease incidence of SSR as they are capable of modifying the microclimate and creating various environments that affect all levels of the disease cycle. Several researchers have proven that moderate temperatures and moisture is required for sclerotia germination, increasing temperatures and decreasing relative humidity is required for day time release of ascospores and moisture and humidity is required within the canopy for spore germination on petals and for further infection. This study attempts to validate these findings and more accurately depict the specific environmental conditions, and canopy densities most favourable to disease development and incidence. By understanding the environmental requirement for SSR, cost effective management strategies can be implemented based on the findings obtained within this study. More importantly, weather can be used as an indicator of risk in canola crops in Manitoba which can be used to determine appropriate fungicide application rates and timing.
Transcript of Analysis of Weather, Microclimate and Canopy Density … pdf/Day_1_R… · Analysis of Weather,...
Analysis of Weather, Microclimate and Canopy Density on Sclerotinia Stem Rot Disease in Canola
Reanne Pernerowski 1, Paul Bullock 2, Dilantha Fernando 3
Sclerotinia stem rot disease (SSR) in an increasingly important disease in the Canadian prairies creating unpredictable yield losses ranging between 5 and 100 percent in Manitoba. Management is extremely important due to the little commercially available resistant canola varieties. Caused by the fungus Sclerotinia sclerotiorum, sclerotinia begins its life cycle as sclerotia in the soil. Under specific environmental conditions sclerotia germinates and eventually releases ascospores into the surrounding atmosphere. Ascospores land on senescing flower tissue of the canola plant and subsequently land on the leaves and stems and begin to kill the entire plant.
Canopy density and weather are important factors known to influence disease incidence of SSR as they are capable of modifying the microclimate and creating various environments that affect all levels of the disease cycle. Several researchers have proven that moderate temperatures and moisture is required for sclerotia germination, increasing temperatures and decreasing relative humidity is required for day time release of ascospores and moisture and humidity is required within the canopy for spore germination on petals and for further infection. This study attempts to validate these findings and more accurately depict the specific environmental conditions, and canopy densities most favourable to disease development and incidence. By understanding the environmental requirement for SSR, cost effective management strategies can be implemented based on the findings obtained within this study. More importantly, weather can be used as an indicator of risk in canola crops in Manitoba which can be used to determine appropriate fungicide application rates and timing.
Reanne Pernerowski Dr. Paul Bullock, Dr. W.G Dilantha Fernando University of Manitoba
Analysis of Weather, Microclimate and Canopy Density on Sclerotinia Stem Rot
Disease in Canola
Sclerotinia Stem Rot (SSR) Canadian Prairies
• Fungus Sclerotinia sclerotiorum
• Economically important disease of canola
• Reduce yields by 0.4 to 0.5 times the percentage of
infection (Manitoba Agriculture)
• Losses ranging from 5-100%
3
Disease cycle of Sclerotinia
Apothecia germination Windborne ascospores
Lesions spread on stem Sclerotia form in stem Leaf infection
Petal infection
Infection stage
Management of SSR • Crop rotations (4 years) with non host crops
– Limitations • Genetic Resistance
– Cultivar availability
• Fungicide applications – Costly, timing
• Biological control agents • Tillage • Seeding rates and row spacing • Disease forecasting
Presenter
Presentation Notes
Not many non host crops, long rotation periods
Objectives 1. Impact of microclimatic conditions in varying
canopy densities on S. sclerotiorum 2. Assess risk of SSR disease on canola based on
standard weather conditions 3. Impact of a disease infected field containing a non-
host wheat crop on sclerotinia disease development and spread by spore dispersal
Study Sites and Layout
• Carman – 2011 – 2012
• Winnipeg – 2011 – 2012
• 3 treatments of high, medium and low seeding rates and fertilizers treatments
Field Setup • Even Inoculation
– Canola, Wheat
• Weather station – Wind, RH, temperature, solar
radiation, rainfall
• Microclimate stations – RH, temperature, soil moisture
and temperature, leaf wetness
• Misting • Rotorods
Carman 2012 Carman Flowering 2011
Effects of Canopy Density and Misting on Microclimate and
Disease
Seeding Rate – Crop Density
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
June 30, 2011 July 5, 2011 July 12, 2011 July 21, 2011
WINNIPEG CARMAN 2011
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
July 8, 2011 July 11, 2011 July 19, 2011 July 27, 2011 August 3, 2011
2011
LOW MEDIUM HIGH
Presenter
Presentation Notes
Blue: high Green: medium Red: low Significance bw high and low seeding rates for both fields in 2011
Hourly Relative Humidity among Canopy Densities
30
40
50
60
70
80
90
100
110
2011/07/02 12:00 2011/07/04 0:00 2011/07/05 12:00 2011/07/07 0:00
Rela
tive
Hum
idity
(%)
0% to 30% flowering
High Medium
Low
• Winnipeg 2011
FLOWERING PERIOD Average RH: significant differences among all plot densities
Presenter
Presentation Notes
A high, medium and low density plots indicated by the arrows Significant impacts are shown by the density differences on relative humidities with higher RH at higher density plots Similar trend throughout flowering period Makes sense due to large differences in LAI density differences
Hourly Temperature among Canopy Densities
• Winnipeg 2011
5
10
15
20
25
30
35
2011/07/02 0:00 2011/07/04 0:00 2011/07/06 0:00 2011/07/08 0:00
Tem
pera
ture
(Deg
rees
Ce
lsiu
s)
0% to 30% flowering
FLOWERING PERIOD Average Temperature: significant differences among all plots densities
High
Medium
Low
Total Daily Mean Ascospore Concentrations (ascospores/m3)
WINNIPEG 2011 WINNIPEG 2012
CARMAN 2011 CARMAN 2012
R² = 0.0033
R² = 0.0005
R² = 0.257
R² = 0.1507
400
600
800
1000
1200
1400
1600
1800
2000
1.00 2.00 3.00 4.00 5.00
Asco
spor
e Co
ncen
trat
ion
(asc
ospo
res/
m3 )
LAI
R² = 0.0217 R² = 0.0087
R² = 0.2206
R² = 0.0001
200
400
600
800
1000
1200
1400
1600
1800
2000
0 50 100 150 200 250
Asco
spor
e Co
ncen
trat
ion
(asc
ospo
res/
m3 )
plants/m3
Percentage of Infection
R² = 0.2856
R² = 0.0679 0
5
10
15
20
25
30
35
0.00 1.00 2.00 3.00 4.00 5.00
Perc
enta
ge o
f Inf
ectio
n (%
)
LAI
R² = 0.0686
R² = 0.3383
0
5
10
15
20
25
30
35
0 100 200 300
Perc
enta
ge o
f Inf
ectio
n (%
)
Plants/m3
WINNIPEG 2011 WINNIPEG 2012
CARMAN 2011 CARMAN 2012
Misting (2011)
Winnipeg 2011 Misted Non-Misted
Leaf Area Index 3.2 3.0
Plant Counts (plants/m3) 133.1 148.3
Relative Humidity (%)* 78.2 76.6
Leaf Wetness* 32.9 24.4
Air Temperature (°C)* 20.6 20.8
Soil Temperature (°C)* 20.4 20.4
Ascospore Concentration (ascospores/m3) 628 705
Percentage of Infection (%) 6 14
Potential Relationships between Weather Variables and Ascospore Dispersal
Mean Daily Ascospore Concentrations Carman and Winnipeg Overlay (2011)
0
500
1000
1500
2000
2500
300011
-Jul
12-J
ul
13-J
ul
14-J
ul
15-J
ul
16-J
ul
17-J
ul
18-J
ul
19-J
ul
20-J
ul
21-J
ul
22-J
ul
23-J
ul
24-J
ul
25-J
ul
26-J
ul
27-J
ul
28-J
ul
29-J
ul
Mea
n Da
ily A
scos
pore
Con
cent
ratio
ns
(Asc
ospo
re/m
3)
Date
CarmanWinnipeg
Precipitation on Ascospore Concentrations
0
2
4
6
8
10
12
14
0
500
1000
1500
2000
2500
300005
-Jul
07-Ju
l
09-Ju
l
11-Ju
l
13-Ju
l
15-Ju
l
17-Ju
l
19-Ju
l
21-Ju
l
23-Ju
l
25-Ju
l
27-Ju
l
29-Ju
l
31-Ju
l
02-A
ug
04-A
ug
06-A
ug
08-A
ug
10-A
ug
12-A
ug
14-A
ug
16-A
ug
Tota
l Dai
ly R
ainf
all (
mm
)
Mea
n D
aily
Asc
ospo
re C
once
ntra
tion
(Asc
ospo
res/
m3 )
CARMAN – 2011
• Qandah and Mendoza (2011): ascospore release during elevated periods of RH followed by rapidly decreasing RH
Analysis of Spore Release Dispersal from a Non-Host Wheat Crop
684 604 727
682
723 673
659 662
707
748 603 640
Wind on Mean Ascospore Concentrations (ascospores/m3)
DOMINANT WIND DIRECTION
CA
NO
LA
WH
EAT
N
E S
W CARMAN 2011 57
7 a/
m3
- 19
%
622
a/m
3 - 3
0 %
655
a/m
3 - 1
6 %
Presenter
Presentation Notes
Wheat not biggest contributing factor to ascospore concentrations and disease incidence in neighbouring canola field Higher concentrations in bar soil closer to canola compared to wheat in both carman fields (2011 and 2012)
Interpretation –Canopy density and misting –Crop rotations –Weather forecasting and fungicide use
Brenleigh Ramm Samantha Erichsen Ives Nikiema
Presenter
Presentation Notes
Additional data analysis required to determine exactly what is influencing the pathogen, we know so far that canopy density plot treatments alone do not influence the spread of ascospores or the onset of disease it may however have an influence on the germination of sclerotia at the beginning of the life cycle of the disease, however this is not studied here spore dispersal needs to be observed over time and compared with other microclimate and weather factors also a more in depth analysis of individual plots needs to be completed, due to possibility of weeds/ other factors affecting these results analysis of spore dispersal in neighbouring wheet field to see if we can quantify the distance travelled by these spores and the effects of non host crops The insignificant results can be interpreted in many ways ascospore release and dispersal may be more sporadic than we think ascospores can also be spread further than the plot limitations disease incidences not coordinating with plot densities may be linked to the nature of spore dispersal within the plots it may be possible that spore dispersal and disease is not influenced by factors affected by canopy desnity such as RH and Temperature, there may be more significant underlying factors affecting disease development
Acknowledgements
• Canola Council of Canada • Advisors, Drs. Paul Bullock and W.G. Dilantha
Fernando • Technicians Paula Parks, Tim Stem, Bo Pan and
Besrat Demoz • Summer students (Michael Chiasson, Jennifer
Ellis, Brenleigh Ramm, Michelle Lacroix, Samantha Erichsen, Ives Nikiema and Todd Pernerowski)
Fungicides Used
• Lance • Vertisan • Astound • Iprodione • Proline • Quadris • Serenade • Biological control agent: Contans
Petal Sampling 2011 • Rose Bengal Agar • Sampled twice
– 30% bloom – 70% bloom
2012
• Semi- selective media • Sampled 3 times
– 20% bloom – 30% bloom – 70% bloom
Presenter
Presentation Notes
2011 Identification: sclerotia bodies forming, white mycelium, agar turns clear -results: no patterns, sclerotinia identified in a couple plots only on certain petals in both years 2012 identification: blue to greenish yellow, sclerotia bodies and white mycelia
Wind Speed on Ascospore Concentration
CARMAN 2011
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0
500
1000
1500
2000
2500
3000
Aver
age
Win
d Sp
eed
(m/s
)
Mea
n Da
ily A
scos
pore
Co
ncen
trat
ion
(asc
ospo
res/
m3 )
WINNIPEG 2011
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0
500
1000
1500
2000
2500
30-Jun 04-Jul 08-Jul 12-Jul 16-Jul 20-Jul 24-Jul 28-Jul
Ave
rage
Win
d Sp
eed
(m/s
)
Mea
n D
aily
Asc
ospo
re
Conc
entr
atio
n (a
scos
pore
s/m
3 )
Wind Speed on Ascospore Concentration CARMAN 2012
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0
1000
2000
3000
4000
5000
6000
23-Jun 25-Jun 27-Jun 29-Jun 01-Jul 03-Jul 05-Jul 07-Jul 09-Jul 11-Jul 13-Jul 15-Jul 17-Jul 19-Jul 21-Jul 23-Jul 25-Jul
Aver
age
Win
d Sp
eed
(m/s
)
Mea
n D
aily
Asc
ospo
re
Conc
entr
atio
n (a
scos
pore
s/m
3 )
0
2
4
6
8
10
12
14
0
1000
2000
3000
4000
5000
6000
23-Ju
n
24-Ju
n
25-Ju
n
26-Ju
n
27-Ju
n
28-Ju
n
29-Ju
n
30-Ju
n
01-Ju
l
02-Ju
l
03-Ju
l
04-Ju
l
05-Ju
l
06-Ju
l
07-Ju
l
08-Ju
l
09-Ju
l
10-Ju
l
11-Ju
l
12-Ju
l
13-Ju
l
14-Ju
l
15-Ju
l
16-Ju
l
17-Ju
l
18-Ju
l
19-Ju
l
20-Ju
l
21-Ju
l
22-Ju
l
23-Ju
l
24-Ju
l
25-Ju
l
Hour
s with
Win
d Sp
eed
grea
ter t
han
4 m
/s
Mea
n Da
ily A
scos
pore
Co
ncen
trat
ion
(asc
ospo
res/
m3 )
