Root Diseases
Armillaria root disease
Armillaria root disease (Armillaria ostoyae (Romagn.) Herink) can attack all native conifer species in British Columbia. Armillaria can be found throughout the province south of 57 degrees latitude. The symptoms are similar to other root diseases: chlorotic and thinning foliage, reduced leader growth, a distress cone crop, and red foliage at death. Other symptoms are basal resinosis, a bent top and stringy, yellowish advanced decay with black zone lines. The signs of Armillaria root disease are: whitish mycelia fans between the bark and the wood, honey colored fruiting bodies in clumps around the root collar of infected trees in the late summer to fall and black rhizomorphs, 1-2mm diameter near the roots (Finck et al. 1989; Root Disease Guidebook 1995). Armillaria root disease causes significant growth reduction and can cause mortality. On the coast mortality from Armillaria root disease seldom exceeds 2-3 percent of a stand, but in the interior 30 percent of a stand can be killed due to Armillaria (Finck et al. 1989). Armillaria can infect new hosts via root grafting, root contact or rhizomorphs. The average yearly rate of spread in active disease centres is between 0.7 and 1.3 meters (Peet et al. 1996). The disease can remain infectious in old stumps for up to 35 years (Root Disease Guidebook 1995).

Laminated root rot (Phellinus weirii)
Laminated root rot is caused by Phellinus weirii (Murr.) Gilberston, and is widespread throughout southern British Columbia. Phellinus attacks a broad range of conifer species in southern British Columbia but its primary host is Douglas-fir. The tree species impacted are broken down into highly susceptible, intermediately susceptible, tolerant, resistant and immune (Thies and Sturrock 1995). Highly susceptible species are: Douglas-fir, grand fir, and mountain hemlock. Intermediately susceptible species are: Engelman spruce, noble fir, Pacific yew, sitka spruce, subalpine fir, western hemlock and western larch. Tolerant species are lodgepole pine and western white pine. Some species are considered resistant, these are: ponderosa pine and most cedar species. Hardwoods are considered immune (Thies and Sturrock 1995).

The symptoms of Phellinus weirii are chlorotic and thinning foliage, reduced leader growth, and a distress cone crop. Centers of infection will be apparent by a number of trees that have fallen in different directions. The roots of the down trees have typically broken off close to the root collar and have the appearance of a root ball. Closer examination of the root ball may reveal chocolate coloured or light gray mycelia on the outside of the bark on infected roots. Fungal growth on the heart wood first appears as reddish staining and is then followed by the wood being decayed into distinct layers, delaminated at the spring wood boundaries. The sheets have a pitted appearance and are occasionally covered with brown lines caused by setal hyphae.

Losses from laminated root rot can reach 50% of a stand. Damage from this disease is in the form of growth loss and mortality. Laminated root rot can live in dead material for many years and will spread to regenerating trees when their roots come in contact with the inoculum (Fink et al. 1989).

Tomentosus (Inonotus tomentosus)
Tomentosus root disease is caused by Inonotus tomentosus fungi. This fungi causes mortality, stem rot, slowed growth, and increases susceptibility to wind throw. The disease attacks: amabilis and subalpine fir, black, white, and Engelmann spruce, lodgepole, and ponderosa pine, Douglas-fir, western hemlock, and western larch.
Symptoms include: thinning crown, reduced growth, foliage discoulouration, mortality, and distress cone crops. Fruiting bodies can occasionally be seen on the forest floor adjacent to infected material in the late summer these are characterized by a yellow-brown, leathery, velvet textured fruiting bodies. Decay appears as honeycomb pitted wood.

Blackstain (Leptographium wageneri)
Black stain root disease in BC is caused by two fungi each specific to the host species. Lodgepole pine and Douglas-fir are the primary hosts of blackstain root disease. There have been cases of blackstain root disease found of hemlock, spruce, western white pine, and ponderosa pine.

Mortality occurs in 15 – 60 year old Douglas-fir and 45 – 100 year old lodgepole pine stands. Symptoms include: thinning crown, reduced growth, foliage discolouration. These symptoms are usually concurrently accompanied by the purple / black staining of the wood beginning at the roots and often extending up the bole of the tree. This staining is usually in the form of long streaks extending upwards.

Needle Casts
Lophodermella
Primarily infects lodgepole pine. Needles infected turn brown then straw coloured. Fruiting bodies develop on the underside of the needle. The needles are shed during the fall through winter leaving only the current years growth.

Dothistroma (Mycosphaerella pini)
Dothistroma needle blight affects various species of pine in British Columbia: lodgepole, ponderosa, and other pine species. Typically the lower crown of the tree is most severely affected. Red – yellow brown bands appear on the needles. The needle tips then turn brown with the needle bases remaining green. Small black structures form on the dead portion of the needle these are the fruiting bodies.
Where infection occurs significant damage can occur. This disease can spread rapidly and defoliate trees in weeks. With repeated infections tree mortality can occur.

Atropellis canker (Atropellis piniphila)
Attacks lodgepole and ponderosa pine. This disease causes a long depression on the stem. Small black fruiting bodies form in the center of the depression. Below the bark / canker there is characteristic black staining. Multiple cankers may kill a tree and cankers may cause stem breakage.

Comandra blister rust (Cronartium comandrae)
Comandra blister rust affects 2 and 3 needle pines (lodgepole and ponderosa pine). The fungus enters through a needle and enters the stem or branch. Infection is characterized by orange coloured margin and long often diamond shaped cankers. Often aecial blisters form within the margins of the canker eventually the blisters burst exposing orange coloured spores. These cankers grow in size vertically and laterally on the stem. Cankers that completely encircle the stem (girdle) will kill the tree above the canker.

White pine blister rust (Cronartium ribicola)
This fungus affects five needle pines (western white pine, whitebark, sugar, limber, and eastern white pine. White pine blister rust was introduced to North America and as such native pine species are strongly susceptible to infection.

Infection can be identified by red flagged branches, diamond shaped cankers with orange margins, orange blisters on the stem or branch, and resin flow. Cankers grow vertically and laterally on the stem. The growth of the canker around the stem girdles the tree; girdling will kill the tree above the canker.

Infection occurs via spores which infect the tree through the needles. These spores originate on the alternate host for the fungus (Ribes).

Dwarf Mistletoes
Lodgepole pine dwarf mistletoe (Arceuthobium americanum Nutt. Ex Englemann) is a parasitic flowering plant. Its primary host is lodgepole pine, but Ponderosa pine, interior spruce and Douglas-fir can be affected. Lodgepole pine dwarf mistletoe can be found throughout the range of lodgepole pine in the interior of B.C. Dwarf mistletoe grows on the host trees stem and branches and depends on the host for support, water and nutrition. Male and female plants both grow on the same tree but not from the same infection. The life cycle, from the initiation of a new infection to seed production, is at least 3-5 years (Dwarf Mistletoe Guidebook 1995). The mature seeds are explosively ejected, up to 15 m, from the female plant. The seeds must land on a susceptible host to survive. The mistletoe induces swelling of the bark and wood at the infection site and adjacent buds and branches are stimulated to grow excessively, creating “brooms.” The infection results in reduced growth rates and volume and decreased strength and quality of wood. Young infected trees can be killed or may never reach a merchantable size (Finck et al, 1989).