Ravjit Khangura

Unravelling factors affecting
Sclerotinia stem rot in canola
particularly in the light of
fungicide spray decisions
Ravjit Khangura
25 Feb 2015
Outline
1.
2.
3.
4.
5.
Sclerotinia levels
Epidemiology
2014 Petal testing
Case studies
Key messages
Photo: Kith Jayasena, DAFWA
Sclerotinia Stem rot incidence in WA in 2014
•
•
•
•
•
Widespread but not severe
Few crops still suffered economic losses
Early development of apothecia
Less favourable conditions post flowering
Sclerotinia caused an estimated loss of $23M
in 2014
Sclerotinia Life Cycle
• Insert Text here
Epidemiology of SSR: Pre-infection
• Spore trapping
• Apothecia monitoring
• Petal testing
Petal Testing
• 2010-2014
• 6 sites
• Daily temperature, rainfall and relative
humidity recorded
Petal testing – Key findings
• Timing and frequency of petal infection
depended on
– Rainfall*
– Relative humidity*
• Air and soil temperature not significant
Conditions prior to max petal infection
Rainfall (mm), mean air
and soil T (⁰C), RH (%)
100
80
Rain
60
mean T
40
mean soil T
20
mean RH
0
29-Jun
Rainfall (mm), air and soil
T (C), RH (%)
Conducive year
6-Jul
100
80
Rain
60
mean T
40
mean soil T
20
mean RH
0
22-Jun
29-Jun
6-Jul
Non conducive year
Conditions after max petal infection
Rainfall (mm), mean air
and soil T (°C), RH (%)
100
80
rainfall
60
mean T
40
Soil meanT
20
mean RH
Conducive year
0
(Rainfall (mm), mean air
and soil T (°C), RH (%)
27/07
3/08
100
80
rainfall
60
mean T
40
Soil meanT
20
mean RH
0
27/08
3/09
Non conducive year
Mean air temperature (Chapman)
Temperature (⁰C)
25
20
Mean T 2010
15
Mean T 2011
Mean T 2012
10
Mean T 2013
Mean T 2014
5
0
11-Jun
1-Jul
21-Jul
10-Aug
30-Aug
19-Sep
9-Oct
Large scale petal testing in 2014
• Southern/South Coastal region
– 10 shires
• >200 samples
– 10 varieties
• sclero selective medium
Mean PPI
Mean Petal infection in different shires
70
60
50
40
30
20
10
0
d
cd
bcd
ab
a
ab
abc
abc
abc
abc
% petal infection
Percent petal infection-TOS
100
90
80
70
60
50
40
30
20
10
0
16/04/2014
1/05/2014
16/05/2014
Tme of Sowing
31/05/2014
Petal infection vs Stem infection 2014
70
Stem infection
60
50
40
30
20
10
0
0
20
40
60
80
Petal infection (%)
From 20 of 200 paddock validated for stem infection
100
Case study 1: Moora
2100
40
2000
30
1900
20
Yield (Kg/ha)
Disease incidence
1800
10
1700
0
Product A @
1.5L/ha
Product A @ 1
L/ha
Prosaro @
450ml/ha
Nil
Rain (mm), mean RH (%),
PI (%)
100
80
Rain
60
mean RH
40
PI
20
0
14/07/14
21/07/14
28/07/14
4/08/14
11/08/14
18/08/14
Case study 2: Wagin
14
2200
12
2100
10
2000
8
1900
6
Yield (Kg/ha)
Disease incidence
4
1800
2
0
1700
Product A @ Product A @ 1
1.5L/ha
L/ha
Prosaro @
450ml/ha
Sumisclex @
1L/ha
Nil
Row spacing, Prosaro and Density
Treatment
Prosaro @ 450ml/ha
Nil
Treated @ 30% bloom
Disease
incidence
lsd
Yield/h
a
S.E.
24
13*
12
2359
2568*
75
100
90
80
Variety
Cobra
Hyola 404
70
16*
21
4
2247
2725*
43
60
Rainfall
50
mean air T
40
Row spacing
22cm
44cm
mean RH
30
18
19.5
4
2452
2520
51
20
10
0
Plant density
15 plants /m2
30 plants /m2
3/07
17.7
19.7
4
2418
2554*
41
Estimated ROI from using Prosaro $50/ha
18/07
2/08
17/08
Decision to spray
>40mm rain, >75% RH
Where to from here?
WA Sclerocast
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Regional risk forecast
Validation
Yield loss model
Sclerotinia e-guide
Key Messages
– Breakthrough in understanding the triggers
– >40mm rain and >75% RH in the 3 week
period before and after early bloom
– Temperature doesn’t seem to be a limiting
factor
– WA’s first Sclerocast is on the way
Acknowledgements
• Grains Research and Development Corporation
• A. Van Burgel, M. Aberra, JP Collins, M. Salam, J.
Lemon, WJ MacLeod, C. Beard, A. Smith, J. Galloway
and R. Loughman
• Geraldton RSU, GSARI
• Ashton Gray (ConsultAg), D. Cameron (Farmanco),
Tim Scott (Agvivo)
• Several WA Canola Growers
Thank You
Questions?
Ravjit Khangura
089368 3374
ravjit.khangura@agric.wa.gov.au