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