Sudden Oak Death
Pest Alert:
Sudden oak death update (February 8,2007) Click
here for more details
(Click on an image below to see the captioned full-size version) |
|
|
|
|
|
|
|
|
|
|
|
|
Figure
1 |
|
Figure
2 |
|
Figure
3 |
|
Figure
4 |
|
Figure
5 |
|
Figure
6
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure
7 |
|
Figure
8 |
|
Figure
9 |
|
Figure
10 |
|
|
|
|
Scientific
Name (of causal agent): Phytophthora ramorum
Common Name (of disease):
Sudden Oak Death, ramorum blight, ramorum die-back
Known Hosts:
Bark Canker hosts
(infection in trunks):
On the west coast species that have been infected include
coast live oak (Quercus agrifolia), black oak
(Quercus kelloggii), Shreve oak (Quercus
parvula), tanoak (Lithocarpus densiflorus).
At least two eastern oak species, northern pin oak (Quercus
palustris) and northern red oak (Quercus rubra)
are susceptible to the disease when inoculated with
the pathogen in the laboratory.
Foliar hosts
(infection in leaves and small branches):
Rhododendron (including azalea)-[all
species, hybrids, and cultivars], Viburnum
spp., Camellia spp., Pieris spp.,
huckleberry (Vaccinium ovatum), bay laurel
(Umbellularia californica), madrone (Arbutus
menziesii), California buckeye (Aesculus californica),
tanoak (Lithocarpus densiflorus)
Rhododendron and Kalmia native to the eastern region are very susceptible in lab testing.
For the APHIS List of Plants Regulated
and Associated with Phytophthora ramorum see:
http://www.aphis.usda.gov/plant_health/plant_pest_info/pram/downloads/pdf_files/usdaprlist.pdf
For a review of the natural hosts
of P.ramorum and lab susceptibility tests completed
see:
Hosts of Phytophthora ramorum with notes on geographical distribution and mating types) from the Canadian Food Inspection Agency http://nature.berkeley.edu/comtf/pdf/P.ramorum.hosts.June.2003.pdf
Symptoms on bark canker hosts: |
|
Black or reddish
ooze bleeding from cankers (Figure 1) |
|
Under the bark, black zone
lines surround necrotic tissue (Figure 2) |
|
Crown dieback and tree mortality.
Trees may retain the brown leaves for months. (Figure
3)
|
Symptoms on Rhododendron (foliar host): |
|
Leaf spots with
a diffuse margin. (Sunburned leaves have a sharper
margin.) (Figure 4) |
|
Twigs have a brown to black
cankers. (Figure 5). |
Symptoms on Viburnum (foliar host): |
|
Infection begins
at the bases of the stem. Stem shows discoloration.
(Figure 6) |
|
Wilting of the entire plant.
(Figure 7) |
|
Leaf lesions and shoot dieback.
(Figure 8) |
Symptoms on Pieris and Camellia (foliar
host): |
|
Camellia-
Leaf lesions at leaf tip or margin with diffuse
margins. (Figure 9) |
|
Pieris- Necrotic
leaf spots and shoot dieback (Figure 10) |
Similar disease symptoms or insect damage:
Oaks
Oak wilt, Oak decline, red oak borer damage
USDA Pest Alert describes Eastern Oak disorders
http://www.na.fs.fed.us/spfo/pubs/pest_al/sodeast/sodeast.htm
Rhododendron
Many
Phytophthora spp. cause similar symptoms. Laboratory
analysis is needed to differentiate between Phytophthora
species.
Foliar damage caused by P.ramorum looks similar
to damage caused by abiotic factors such as cold, drought,
sun scald, and chemical injury. The margins of lesions
caused by Phytophthora are fuzzy while the
margins of the lesions on sunburned leaves are distinct.
Fact sheets and references:
USDA/APHIS Sudden Oak Death Website
contains regulatory information, hosts lists, and current
updates on the SOD situation in the U.S.
http://www.aphis.usda.gov/plant_health/plant_pest_info/pram/index.shtml
USDA Forest Service Sudden Oak
Death Website
Forest Service Fact Sheets and links to other sources
http://www.na.fs.fed.us/SOD/
CAPS/NAPIS Sudden Oak Death website
Maps of SOD from CAPS survey
http://www.ceris.purdue.edu/napis/pests/sod/
California Oak Mortality Task Force
Many excellent resources on SOD including full color
nursery diagnostic guides
http://www.suddenoakdeath.org/
USDA, APHIS publication showing symptoms on foliar hosts
http://www.aphis.usda.gov/plant_health/plant_pest_info/pram/downloads/surveyplan/appendixd.pdf
Phytophthora ramorum-
A Guide for Oregons Nurseries.
http://oregonstate.edu/Dept/nurserystartup/feature/OSUP.ramorum.pdf
Phytophthora ramorum-
The Situation in the UK and EU by Dr David Slawson,
Principal Plant Health & Seeds Inspector, York,
United Kingdom
http://www.defra.gov.uk/planth/phnews/ukandeu.pdf
Phytophthora ramorum a
threat to our trees, woodland and heathland from DEFRA
(Department for Environment, Food and Rural Affairs)
http://www.defra.gov.uk/planth/pestnote/newram.pdf
Fact sheet from the North Central
IPM center
http://www.ncpmc.org/alerts/suddenoakdeath/suddenoakdeath.pdf
last reviewed February 25, 2008 |