Phytophthora ramorum as a Threat to
Oak Woodlands: Potential and Reality
Manfred Mielke for Steve Oak
USDA Forest Service, Northeastern Area
National FHM Meeting, San Antonio, TX February, 2008
Phytophthora ramorum in Oak Woodlands--
Potential
• Host abundance
– Resources at risk
• Oak importance, value nationally
– Greater elsewhere than in west coast Pr endemic area
• History of resource damage from other
introduced pathogens and insects
• Evolving (unstable?) regulation
“Sudden Oak Death”
Distribution- North America
February 2008
Tree-killing disease in
14 Central Coastal CA
Counties
&
Curry County, OR
(county range unchanged since 2004)
59 host/associated host
genera worldwide
San Francisco
Worldwide Phytophthora ramorum
Host & Associated Genera Common in Eastern Forests
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Abies (fir)
Acer (maple)
Aesculus (buckeye)
Arctostaphylos (kinnikinick)
Calycanthus (sweet bush)
Castanea (chestnut)
Corylus (hazelnut)
Euonymus
Fagus (beech)
Fraxinus (ash)
Gaultheria (teaberry)
Kalmia (mountain laurel)
Hamamelis (witch hazel)
Leucothoe (doghobble)
•
•
•
Lonicera (honeysuckle)
Magnolia
Maianthemum (false Solomon's
•
•
•
•
•
•
•
•
•
Pieris (fetterbush)
Prunus (cherry)
Quercus (oak)
Rhamnus (buckthorn)
Rhododendron
Rubus (salmonberry, blackberry)
Salix (willow)
Toxicodendron (poison oak, ivy)
Vaccinium (huckleberry,
•
seal)
blueberry)
Viburnum (arrowwood)
Prevalence of Oak Forests in the Eastern US
• Oak-Hickory
– 9 forest types
– 50.1 million ha
• Oak Pine
– 8 forest types
– 13.7 million ha
• Lowland Oak
– 3 forest types
– 4.1 million ha
20 forest types – 67.8 million ha
46 percent of timberland area in oak-dominated
forests in 37 states
Source: FIA Eastwide Forest Inventory Database
Eastern
Oak Density
Timberland with
> 25 % oak basal
area
FIA Eastwide Forest
Inventory Database (adapted
from McWilliams, et al.).
al.)
Oak Wildlife Habitat Value
Exceeds Wood Product Value
History
“We are perhaps entitled to speculate
that our chronic and alarming problems
with the gypsy moth and other oak
defoliators in the eastern or
Appalachian portions of the mixed
deciduous forest could be as evil a
consequence of the chestnut blight as
the loss of chestnut itself.”
Smith, David M. 1976. Changes in Eastern Forests Since 1600 and
Possible Effects. IN: Anderson and Kaya, eds. Perspectives
in Forest Entomology. Academic Press, New York, New
York.
Evolving Regulation
•
•
•
•
January 2001- OR emergency order
March 2001- Canada quarantine
February 2002- US interim regulation
23 modifications of the federal
regulation between July 2002 and the
present
Incorporating New Knowledge
Changing Balance Between Protecting Commerce
and Protecting Resources
Phytophthora ramorum in Oak Woodlands--
Reality
• Nursery disease history
• Epidemic progress in endemic areas
– Managed vs. unmanaged
• Stream baiting detections
United States Department of Agriculture
Animal and Plant Health Inspection Service
Plant Protection and Quarantine
History of P. ramorum in US Nurseries
The first detection of P.
ramorum in a U.S. nursery
was in 2001 when a
nursery in Santa Cruz, a
quarantined county, was
found with infected
Rhododendron plants.
Year
# Positive
# Growers
2000
0
0
2001
1
1
2002
0
0
2003
20
4
2004
176
17
2005
99
41
2006
61
25
2007
22
9
United States Department of Agriculture
Animal and Plant Health Inspection Service
Plant Protection and Quarantine
Positive Nursery Detections – 2004
25
24
53
1
1
AK
1
3
2
1
3
11
HI
16
4
1
2
3
9
No Nursery-Associated
Positive
Nursery-Associated
Positive
5
6
176 Positive Sites
3
2
United States Department of Agriculture
Animal and Plant Health Inspection Service
Plant Protection and Quarantine
Positive Nursery Detections 2006
11
1
13
1
1
1
28
No Nursery-Associated
Positive
AK
1
HI
1
1
2
61 Positive Sites
Nursery-Associated
Positive
P. ramorum Persistence/Recurrence in Nurseries
Water baiting positive downstream from confirmed
positive WA nursery
Filtering/soil baiting positive from confirmed
positive GA, FL nurseries
Sudden Oak Death
Infested Sites and
Quarantine Area
Year = 2001
Quarantine = 9 mi2
Sudden Oak Death
Infested Sites and
Quarantine Area
Year = 2005
Quarantine = 22 mi2
160
Infected
Tanoak
Infested Acres
140
120
100
80
60
40
20
0
2001
2002
2003
2004
2005
2006
2007
Sudden Oak Death
Infested Sites and
Quarantine Area
Year = 2007
Quarantine = 26 mi2
160
Infected
Tanoak
Infested Acres
140
120
100
80
60
40
20
0
2001
2002
2003
2004
2005
2006
2007
Landscape-level spread by wind-driven rain
Spores carried from infected
tanoaks in the overstory to other
healthy overstory tanoaks during
wind-rain events
Proposed
expansion
• Expand area 3-mi in
all directions (166
sq mi)
• Businesses affected
– 12 nurseries
– Two sawmills
– One floral products
company
• Must meet federal
rules
– Monthly inspections
– Compliance
agreements/permits
P. ramorum in Northern
California and Oregon
Acres
5000
4,500
4500
Oregon Infested Acres*
4000
Humboldt Cty. Infested Acres
Brookings
OR
CA
3,853
3500
3000
2500
2,268
2000
1500
1000
500
2
40
5
48
60
123
70
88
128
168
Redway
0
2001
2002
2003
2004
2005
2006
2007
Wild-land Distribution
of P. ramorum
Brookings, OR site
McKinleyville, CA site
Redway, CA site
McKinleyville, CA
European A1 mating type
Proximal to confirmed nursery
Trace back inconclusive
National Stream Site 2007
P. ramorum EstablishmentWhere, When, How?
Lag time between introduction and establishment…
< 10 years? (west coast P. ramorum)
20 years? (Cryphonectria parasitica)
30 years? (Entomophaga miamiaga)
Lag time between establishment and detection…
Preliminary Diagnostic Results
2007 National P. ramorum Early Detection Survey
!P. ramorum positive streams only!
State
CA
OR
WA
MS
All
Pr Positive
Streams
9
2
1
1
13
Attempts
57
26
9
5
97
Isolation
Molecular
Positive Percent Attempts Positive Percent
9
15.8%
111
33
29.7%
12
46.2%
26
19
73.1%
1
11.1%
9
0
0%
0
0.0%
10
1
10%
22
22.7%
156
53
34.0%
2007
Lakeland Nursery, MS
Ditch (Hog Creek)
Lakeland Nursery Watchdog
2006
Rosedale “Creek”, WA
2007
Sammamish Slough, WA