Root Diseases

"All root rots are root diseases, but not all root diseases are root rots!"

Root Rots - Basidiomycetes

Phellinus weirii - Laminated Root Rot (Douglas-fir biotype)

 
Hosts: spruces, true firs, hemlocks, Douglas-fir, larch; pines are tolerant (get the disease but are not as severely affected as other species; hardwoods are immune.

Spread is by root contact, spore infection very rare or non-existent. Ectotrophic mycelium assists in spread and colonizes the surface of roots in mineral soil.
Fruit-body is perennial, brown, flat and is found under windthrown trees.
Decay is a white rot, laminated in appearance.
 
Armillaria ostoyae - Shoestring root rot, Honey Mushroom

 
Hosts: Douglas-fir, true firs, spruce highly susceptible; pines, hemlock, cedar moderately susceptible; birch and larch are tolerant; nothing is immune or resistant.

Spread is by root contact and rhizomorphs; stressed trees may be more susceptible, fungus can alternate from pathogenic to saprophytic phase. On the coast, Armillaria tends to attack trees less than 25-years-old. In the interior it is a pathogen of trees of any age.
Fruit-bodies are mushrooms with gills, honey-coloured, sprout from base of infected trees.
Decay is a yellow-stringy white rot.
Often associated with Fir root beetle(Pseudohylesinus granulatus).
 
Inonotus tomentosus - Tomentosus root rot

 
Hosts: spruce, pines are susceptible; Douglas-fir and true firs somewhat susceptible; hardwoods are immune.

Spread is by root contact and most likely by basidiospores. Most important root disease of central and northern interior.
Fruit-body is annual, light brown, velvety on top, short stalk, funnel shaped with pores
Decay is similar in appearance to that of Phellinus pini. Pitted white rot.
Possibly associated with Warren's root collar weevil(Hylobius warreni)
 
Heterobasidion annosum - Annosus root rot

 
Hosts: in B.C. main hosts are hemlock, true fir and spruce on the coast, not reported from interior pine forests although pine in Europe is very susceptible. Hardwoods are immune.

Spread is by root contact and conidiospores on fresh wounds. Different genetic strains exist, the most common are the S- and P- type (named for the dominant host). S- type is found in B.C. and causes a butt rot. P- type is found in Europe and the US and causes cambial necrosis.
Fruiting body is perennial, dark brown top with white hymenium. Found in root crotches of infected trees.
Decay is a stringy white rot.
 
Phaeolus schweinitzii

 
Hosts: spruces and Douglas-fir are the primary hosts.

Spread is primarily by spores that exist in soil until a host root comes in contact with them.
Fruit-body is large, annual, round and cow-patty like, on a short stalk.
Decay: Causes a brown rot of small roots.

Wilt Diseases - Ascomycetes

Ceratocystis wageneri - Black stain root disease

 
Hosts: pines, Douglas-fir are the major hosts.

In B.C. this disease is most common in the southern interior. Spread is by beetle vectors and root contacts or grafts. Disease is caused by plugging of the vascular system by the hyphae, and there is possibly a toxin involved.