Post on 13-Jan-2016
A spatial model for predicting Swiss needle cast distribution and severity
Jeff Stone and Len CoopDepertment of Botany and Plant Pathology
Oregon State University
Acres of Douglas-fir forest with Swiss Needle Cast Symptoms Detected by Aerial Surveys, Coast Range, Oregon 1996-2006
131,088144,102
172,127
293,649 282,202
212,465
387,040
267,852
176,594
207,090
324,584
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Survey data, two types: area and symptom severity.
Both vary due to annual weather effects
Spatial distribution of disease occurrence and severity are neither random nor uniform
Both temporal and spatial occurrence of disease are affected by short (weather) and long (climate) term meteorological patterns
Average disease severity is related to total area affected
SNC Index = survey area x survey average severity
Annual area and severity of SNC is correlated with seasonally-grouped climate variables that have also been correlated with abundance of P.
gaeumannii
Predicting Swiss Needle Cast Severity
The best predictors of disease severity in permanent study sites are mean daily winter temperature and spring leaf wetness, because of their effects on infection and pathogen growth
Observed Infection Index
0.0 0.1 0.2 0.3 0.4
Pre
dic
ted
In
fectio
n In
de
x
0.0
0.1
0.2
0.3
0.4
one-yr needlestwo-yr needles
R2=0.794
Predicted vs. observed values for amount of infecton in Douglas-fir stands in the Coast Range, based on winter (Dec-Feb) average daily temperature, spring leaf wetness.
Year
0 5 10 15 20
Pseu
doth
ecia
den
sity
(%
)
0
5
10
15
20
Simulation of Phaeocryptopus gaeumannii pseudothecia density over time for one-year-old and two-year-old needles. Mean-daily winter temperature was held constant at 5.13 ºC and the initial infection index was set to 1.0 %.
Mean-daily winter temperature ( oC)
2 4 6 8 10
Pseu
doth
ecia
den
sity
(%
)
-10
0
10
20
30
40
50
Simulated final Phaeocryptopus gaeumannii infection index for one-year-old and two-year-old needles over a range of constant winter temperatures. Vertical lines represent the high (8.90 ºC) and low (3.77 ºC) mean-daily winter temperatures observed from coastal study sites.
2-yr-old
1-yr-old
2-yr-old
1-yr-old
Disease severity prediction for NW Oregon based on DAYMET climate model, 17-year average temperatures
New Zealand Plantations sampled in 2006
Distribution of SNC in New Zealand also is strongly correlated with climate factors affecting abundance of P. gaeumannii
45
Composite Needle Retention
0
5
10
15
20
25
30
35
Karioi
Hanmer
(all)
Gowan
Hills
SS
Golden
Dow
ns P
Gowan
Hills
P
Golden
Dow
ns S
S
Beaum
ont (a
ll)
Skain
garo
a
Kainga
roa
(all)
Waipor
i (all
)
Tauhar
a (all)
Putor
ino
Waira
ngi
Puketitr
i
TeWaka
Nee
de
Ret
enti
on
Sco
reNeedle Retention by Age Class
0
1
2
3
4
5
6
7
8
9
10
Karioi
Hanmer
(all)
Gowan
Hills
SS
Golden
Dow
ns P
Gowan
Hills
P
Golden
Dow
ns S
S
Beaum
ont (
all)
Skaing
aroa
Kainga
roa
(all)
Waip
ori (
all)
Tauha
ra (a
ll)
Putor
ino
Wair
angi
Puket
itri
TeWak
a
Ne
ed
le R
ete
nti
on
Sc
ore
2004 2003 2002 2001
Average needle retention for New
Zealand sites
2004 Infection Index
0.000
2.000
4.000
6.000
8.000
10.000
12.000
14.000
16.000
HS-900
GH-S
S-900
MNK-9
00
GH-P
-900
GD-P
-900
GD-S
S-900
BEAUMT-9
00SK
WAI-9
00TAK
PUKTW
A
KGA-9
00
TAU-900
WRI
PTO
2003 Infection Index
0.000
5.000
10.000
15.000
20.000
25.000
30.000
35.000
40.000
GH-S
S-900
MNK-9
00
HS-900
GH-P
-900
BEAUMT-9
00
WAI-9
00TAK
GD-P
-900
GD-S
S-900
PUKW
RIPTO
TAU-900 SK
TWA
KGA-9
00
Abundance of pseudothecia on one-
and two-year-old foliage
AC 2004 Vs Winter Min Temp
y = 0.3195x - 0.8817R2 = 0.8494
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
0.000 2.000 4.000 6.000 8.000 10.000 12.000 14.000 16.000
Relationship between mean daily minimum winter temperature and P. gaeumannii abundance in New Zealand
Climate/weather factors are the major determinants of P. gaeumannii abundance and SNC severity, regardless
of location
But in western Coast Range, spatial distribution of disease over time is aggregated, does not strictly follow elevational gradients etc.
Distribution and severity of Swiss needle cast 1996-2006, Tillamook area
Cumulative disease distribution appears to be strongly influenced by aspects of topography, wind direction and other meteorological variables in addition to temperature—need to allow for maritime influence in models.
Summer maritime influences cause wind convergence zones (outlined in red)
Convergence zones occur in the near-surface wind field below the marine inversion during onshore flow in marine stratus regimes. These convergence zones typically have the highest occurrence of drizzle and cloud.
Areas of highest disease severity appear to coincide with zones having an optimal mixture of marine drizzle and leafwetness with the warmer temperatures.
Effects of convergence/divergence
Elements are in place to develop a useful, predictive spatial model for Swiss needle cast:
Infection biology, epidemiology, mechanism of pathogenicity of the pathogen are well understood
Environmental variables affecting distribution and abundance of the pathogen are well understood, mechanistic, and strongly correlated with disease distribution.
Sufficiently detailed, high resolution GIS-based climate datasets are available, readily adaptable for SNC modeling.
Considerable data are available on disease distribution and P. gaeumannii abundance over the past ten years, both site specific and aerial survey.
The OSU Integrated Plant Protection Center is a nationally recognized center for plant disease modeling and forecasting.
The PIs combined expertise in GIS-modeling, climate modeling, disease forecasting, and epidemiology of SNC.
Using CALMET and MtnRTCon together to specify marine stratus precipitation in summer for Swiss
Needle Cast Alan Fox
Fox Weather, LLC9/21/06
Sample Products from CALMET
• Map of Temperature• Map of Wind Speed• Map of Mixing Height (base of marine
inversion)
Sample Products from CALMET
Wind Direction/Speed (mph) Mixing Height (meters)
24hr forecast valid 08/29/2006 10am PSTFIGURE 1.
Sample Products from CALMET
24hr Forecast Valid 10am 8/24/2006
Summary of CALMET Forecasts in Figures 1 and 2
• Mixing height = depth of the marine layer (existing below the inversion). The top of the mixing layer would normally correspond to the cloud top in marine stratus patterns.
• Wind direction/speed: shows areas of convergence and divergence around terrain barriers, which, in the marine layer, correspond to zones of relatively deeper or thinner clouds. Deeper clouds correspond to areas of drizzle.
• Temperature (K): the ‘free-air’ temperature at the height that follows the terrain. This is not the same as true surface temperature which has surface radiational heating included.
Background• Current Premise: Moisture and Temperature in winter
has the primary effect on SNC occurrence later in the following late spring.
• Current Premise: Moisture in preceding summer from marine stratus has secondary effect on SNC distribution.
• However: SNC distribution appears to follow the marine stratus regions of occurrence.
• Our Hypothesis: – Marine stratus distribution (drizzle and fog-related leafwetness
during the warm season (late June-early August) sets up the antecedent favorable conditions for SNC growth
– Winter rain distribution is secondary to summertime stratus distribution in specifying the area affected by SNC
Models for SNC Study• Mtnrtcon:
– Horizontal resolution to 2.5 km, but can decrease resolution to 0.2 km (untested).
– Temperature, Dew Point, RH– Wind Speed
• Slopes and peaks• Valleys (direction of wind vs. valley orientation.
– Inversion Base Height• CALMET:
– Resolution to 2 km– Temperature– Wind Speed to 2 km using boundary layer model (Note: cannot
change horizontal or vertical resolution)– Moisture and VV values are calculated but output not currently
available.– Mixing height (corresponds to inversion base height)
Strategy for Analysis
of 2005 Data
• Use Mtnrtcon to analyze specific cases from late June – early August 2005.
– Calculate rain (drizzle) from marine stratus.
– Calculate Tmin and Tmax for the sample days.
What CALMET and Mtnrtcon show about conditions relevant to growth of SNC
• Use CALMET and Mtnrtcon on the 10am LST forecast valid time.
• Marine stratus flag:– Where mixing height<= 1200 m– Where 10am temps are relatively cool, e.g. 283-293K
• Marine drizzle flag:– Where marine stratus flag=yes– Where Wspd<=7 mph– Where mtnrtcon shows 3hr rain>.005.
• 10am Temperature from either CALMET or Mtnrtcon during periods of mtnrtcon rain>.005