Monday, December 7, 2015
Candidate Sword Fern Pests
Provided by Jenny Glass, from the USDA-APHIS Fungal-Host Database
I am not sure that I ever sent you the list of possibilities that I went through during your DEC 2014 submission:
The literature generally suggests the species Polystichum munitum is relatively disease and pest free and an investigation of other Polystichum species revealed more or less the same information. As discussed, the laboratory investigated a similar concern about dying sword fern in the Jefferson County area in 2013. We were also unable to pinpoint the origin of that damage beyond the impression that the sample contained no apparent disease or pest origins of damage.
The USDA-APHIS Fungal-Host Database had these fungi listed as being observed on sword fern but none of the described fungi are likely to be associated as the cause of this patch of dying plants.
Chaetasbolisia falcata: Polystichum munitum: California
Helotium polystichi: (Basidiomycete):
Polystichum munitum (On stems.): California
Herpobasidium abnorme: (reported to cause distortion):
Polystichum munitum: Idaho -
Milesia polystichi - (Milesina winelandi): (rust- obligate parasite unlikely to kill host)
Polystichum munitum: California, Canada, Idaho, Montana, Oregon, Washington
Milesia vogesiaca - (Milesina vogesiaca): (rust- obligate parasite unlikely to kill host)
Polystichum munitum Canada, Oregon
Milesina vogesiaca: (rust- obligate parasite unlikely to kill host):
Polystichum munitum California
Milesina winelandi: (rust- obligate parasite unlikely to kill host):
Polystichum munitum: California, Idaho, Montana, Oregon, Washington
Mycena fragillima: (small saprophytic mushrooms):
Polystichum munitum: California, Oregon, Washington
Phoma adianticola - (Didymella adianticola): Phomopsis sp.:
Polystichum munitum (On fronds.): Oregon
Phyllosticta sp.: Polystichum munitum (On fronds.): Oregon
Phytophthora cinnamomi: (thrives in saturated soils/poor drainage):
Polystichum munitum (Root rot.): California
Pythium sp.: (thrives in saturated soils/poor drainage):
Polystichum munitum California
Rhizoctonia solani: (frond blight is a common symptom):
Polystichum sp.: California
Taphrina faulliana: (leaf blister):
Polystichum munitum: Canada, Idaho, Oregon, Washington
Valdensia heterodoxa: (apparent leaf spot/leaf blight pathogen):
Polystichum munitum: Canada
Xenasma filicinum - (Phlebiella filicina):
Polystichum munitum: Canada
Dr. Marianne Elliott's Report (12/3/2015)
I have attached the sampling procedure and list of samples we collected. We did not find any Phytophthora, but I am not ready to rule it out as the cause of the die-off. It could be a species that is slow growing and difficult to culture, so we missed it. Or it was replaced by something else in dead material. Or this was the wrong time of the year to sample. I think the students who are working on this should keep an eye out for it.
There were a few Pythiums and other similar organisms that we see commonly in soil and roots. We didn't find anything associated with the dying sites vs the healthy sites, or with the dead cedar transplants. I have been asking various people I know and nobody has seen it in their travels, but now they are aware of the situation. I will let you know if anything turns up.
--Marianne
Sample Processing Protocol (Sword fern dieoff samples collected
at Seward Park 11/10/15)
|
Sample #
|
Description
|
Treatment
|
|
1
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5 x 5 plot, healthy, symptomatic fern foliage
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Surface sterilize, plate 5 segments on PARPHV8 (3 plates)
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2
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5 x 5 plot, healthy, crown from healthy fern plant
|
Surface sterilize 10 necrotic root segments per plate (PARPHV8),
dissect crown and look for brown staining symptoms (3 plates). If present,
surface sterilize and plate 5 segments on PARPHV8 (1 plate).
|
|
3
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5 x 5 plot, healthy, soil from base of 3 healthy ferns, upper 5 cm
depth + litter & roots
|
Bait in 1 L bottles. Use rhododendron leaves and healthy sword fern
leaves. Place one intact rhody leaf and one sword fern frond in each of 3
bottles containing 100 g soil and 500 ml water.
|
|
4
|
Ground zero, foliage and fronds from dying ferns
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Surface sterilize, plate 5 segments on PARPHV8 (3 plates)
|
|
5
|
Ground zero, crown and roots from dead ferns
|
Surface sterilize 10 necrotic root segments per plate (PARPHV8),
dissect crown and look for brown staining symptoms (3 plates). If present,
surface sterilize and plate 5 segments on PARPHV8 (1 plate).
|
|
6
|
Ground zero, soil from base of 3 dead ferns, upper 5 cm depth +
litter & roots
|
Bait in 1 L bottles. Use rhododendron leaves and healthy sword fern
leaves. Place one intact rhody leaf and one sword fern frond in each of 3
bottles containing 100 g soil and 500 ml water.
|
|
7
|
Ground zero, soil from base of 3 dead, planted cedars
|
Bait in 1 L bottles. Use rhododendron leaves and healthy sword fern
leaves. Place one intact rhody leaf and one sword fern frond in each of 3
bottles containing 100 g soil and 500 ml water.
|
|
8
|
Symptomatic foliage from other hosts along trail by Ground zero and
road
|
Surface sterilize, plate 5 segments on PARPHV8 (3 plates).
|
Baiting protocol for
soils
Label 1L bottles with sample and rep numbers. Use
rhododendron leaves and healthy sword fern leaves. Place one intact rhody leaf
and one sword fern frond in each of 3 bottles containing 100 g soil and 500 ml
water. Cap tightly and incubate bottles on their sides for 48-72h.
After incubation, remove baits from bottles and rinse with
water, then blot dry. If asymptomatic incubate an additional 3-7 days in
ziplock bags containing moist paper towels. Plate symptomatic areas of foliage
(5 per plate) on PARPHV8. Use two plates for each bait type per bottle.
All samples
Check for Phytophthora colonies on all plates after 2-5 days
and isolate onto small PARP plates for identification.
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