Conifer Stem Decays
Caused by several fungi
Host(s) in Alaska: All conifers
Habitat(s): Most decay heartwood, some occupy sapwood & heartwood
A montage of conifer stem decays found in coastal Alaska.
Select stem decay fungi of Alaskan conifers (updated 2024):
Recent observations, key identification characteristics, and damage information is provided for each species. Click images to view albums of stem decay fungi from the Forest Health Protection, Forest Service, USDA, Alaska Region on Flickr. Detection maps show georeferenced observations of fungi, and many include the modeled range of tree hosts. Host tree distributions were developed by the Forest Health Assessment and Applied Sciences Team in 2011 (240m-resolution, presence based on dominant tree species by tree diameter). View our ground survey data dashboard to view maps and ground survey records of stem decays and other damage agents in Alaska.
Common Species in Alaska
Ganoderma applanatum (Pers.) Pat.
Hosts: Mainly hardwoods; but sometimes western and mountain hemlock, and white and Sitka spruce.
General Distribution in Alaska: Statewide where hosts occur.
Identification: Perennial, woody, fan- or shelf-shaped conk. Usually occurs as a saprobe on decaying logs and stumps. Occasionally found as a heart rot on wounds of living trees. Top: dull, dusty brown to grey-brown with concentric ridges. Bottom: white pore surface that immediately browns when touched. Interior: dark brown to cinnamon.
Damage: Spongy mottled white rot of sapwood and heartwood.
Remarks: Known as the artist’s conk because the fresh pore surface bruises dark brown when touched or scratched. Intricate etchings can be preserved for years if properly dried.
2024 Status/Activity: This common white rot of dead and down hardwoods and conifers across Alaska is considered a species complex that cannot be further distinguished in the field. On hardwoods in Southeast Alaska, the conk tends to be thinner and has a paler upper surface without the abundant dusting of brown spores.
2024 Ground Detection Survey Observations: 21 statewide, 17 across Southeast Alaska mostly on western hemlock, and 4 near Anchorage on balsam poplar and black cottonwood.
2024 iNaturalist Observations: 27 total, 15 in Southeast Alaska from Skagway to Ketchikan, 6 in the Interior, and 6 near Anchorage.
|
Image
A Ganoderma applanatum conk on western hemlock near Juneau, Alaska. Photo Credit: USDA Forest Service photo by Robin Mulvey. |
Image
|
Click the conk image to view full Ganoderma applanatum album on Flickr.
Fomitopsis pinicola sensu lato
Fomitopsis mounceae Haight & Nakasone
Fomitopsis ochracea Ryvarden & Stokland
Hosts: Spruce, hemlock and pine; occasionally western redcedar, birch, and aspen.
General Distribution in Alaska: Statewide where hosts occur.
Identification: Perennial, leathery to woody, flat to vaguely hoof-shaped conk. Found as a firm, rounded white mass on wood surface when young. Primarily saprobic and extremely common on dead wood. Also commonly associated with wounds of live trees, especially Sitka spruce. Top: dark brown to grey to black, zoned, often with reddish brown band near rounded margin. Bottom: creamy white with minute round pores. Inside: creamy white with corky texture.
Damage: Incipient (early) decay has a yellow-brown to brown stain. Wood with advanced decay is a crumbly brown cubical rot. Thick white mycelial felts may form in shrinkage cracks. The mycelial felts are similar to that of the quinine conk but do not taste bitter.
Remarks: Sometimes confused with artist’s conk but bottom pore layer does not immediately bruise when touched. In Southeast Alaska, considered an important stem decay of live spruce, but its brown cubical decay may be confused with that of Phaeolus schweinitzii.
2024 Status/Activity: These are important decay organisms in Alaskan forests, recycling nutrients and leaving brown cubicle rot residues that become the next generation’s soil/nurse-logs. While there are many observations, due to its perennial conk, disease presence or severity has not changed remarkably. Fomitopsis specimens from Interior Alaska and the western Kenai Peninsula have been sent to the Forest Service - Center for Forest Mycology Research to support ongoing studies of Fomitopsis diversity.
2024 Ground Detection Survey Observations: 21 sensu lato, 13 F. mounceae, and 35 F. ochraceae, observations were recorded statewide on white spruce, Sitka spruce, the hybrid Lutz spruce, and mountain and western hemlock.
2024 iNaturalist Observations: 22 sensu lato, 49 F. mounceae, and 114 F. ochraceae observations were recorded statewide, the majority from coastal Southeast Alaska.
|
Image
A large Fomitopsis ochracea (Fomitopsis pinicola sensu lato) conk. Photo Credit: USDA Forest Service photo by Robin Mulvey. |
Image
|
Fomitopsis pinicola sensu lato is a species complex that has recently been redescribed. Many spruce beetle-killed trees in Southcentral are ultimately toppled by this decay fungus, evidenced by brown-crumbly-rot and mycelial expansion through wood. Three species from this complex are present in North America and two in Alaska: F. mounceae has a red-orange band that inspired the common name “red belt conk”, while the upper surface of F. ochracea is dark grey to brown (Haight et al. 2019, Loyd et al. 2018). Fomitopsis ochracea is generally the most common species recorded statewide compared to F. mounceae. iNaturalist is improving our ability to capture georeferenced and photo-documented observations of this very common species complex.
Click the image to view full Fomitopsis pinicola sensu lato album on Flickr.
Phaeolus schweinitzii (Fr.) Pat.
Hosts: Sitka spruce, white spruce, and hemlock; rare on shore pine in Alaska.
General Distribution in Alaska: Common in coastal forests, especially in Southeast Alaska. Occasionally found in boreal forests of the Interior.
Identification: Large, annual, layered fruiting body; shelf-like on lower bole; circular and stalked with sunken center on ground. Develops on both live and dead trees/logs. Turns dark red brown and brittle when dead (resembles cow pie). Top: velvety, yellow to orange when young, turning brown with an olive brown to yellowish margin. Bottom: large, irregularly shaped pores, bright yellow to orange when young becoming greenish yellow, olive, or brown; quickly bruises dark brown.
Damage: Brown cubical butt rot, often extensive. Rapid loss of tensile strength, even at fairly early stages of decay, may lead to breakage on lower bole.
Remarks: Also known as the cow pie fungus, velvet top fungus or dyer’s polypore. Can be used to create yellow, brown, and green dyes. Sometimes confused with Onnia tomentosa.
2024 Status/Activity: Bole snap caused by this pathogen remains common in some primary Sitka spruce forests near Juneau that are transitioning toward old-growth condition. The disease may be key to successional dynamics in young coastal forests dominated by Sitka spruce.
2024 Ground Detection Survey Observations: 14 total, 10 near Juneau, Sitka, and Ketchikan on Sitka spruce in Southeast Alaska, 3 along Turnagain Arm in Southcentral Alaska on white spruce, and 1 on white spruce near Fairbanks in the Interior.
2024 iNaturalist Observations: 20 total, 17 in Southeast Alaska near Skagway, Haines, Juneau, and Sitka, and 3 in Southcentral Alaska from Hope and Moose Pass on the Kenai Peninsula, and Kodiak Island.
Phaeolus schweinitzii is most common in coastal forests of Southeast Alaska on Sitka spruce but has also been recorded on shore pine and white spruce. The fruiting bodies are most noticeable when they emerge from broken tree boles or below-ground roots in late summer and fall. Root and lower bole damage can promote infection, an important management consideration at developed recreation sites. This fungus plays an key role in forest success in even-aged spruce forests, including those originating after glacial recession. Bole breakage of large spruce trees varies forest structure and diversity. The decaying wood of freshly snapped trees can have a strong pleasant licorice fragrance.
Click the image to view full Phaeolus schweinitzii album on Flickr.
Fomitiporia tsugina Murrill (syn. Phellinus hartigii (Allesch. & Schnabl) Pat.)
2024 Status/Activity: In North America, this trunk rot on hemlock has been reclassified as Fomitiporia tsugina (Brazee 2013). This fungus is both a sap rot and heart rot of hemlock. We have observed it killing its host tree within a decade of fruiting body development due to invasion of the sapwood girdling the tree. This fungus can invade through stem wounds, including bole swellings caused by hemlock dwarf mistletoe. A sequenced specimen from Juneau closely matched other species from western North America identified as F. tsugina.
2024 Ground Detection Survey Observations: 6 on western hemlock near Haines, Juneau, Wrangell, and Ketchikan.
2024 iNaturalist Observations: 4 near Sitka and on Mitkof Island.
Hosts: Western and mountain hemlock.
General Distribution in Alaska: Southeast Alaska.
Identification: Uncommon. Light brown perennial conk, often occurs on undersides of limbs or branch stubs, also on tree bole; may be velvety and flattened against tree bole. Top: dark brown to black, cracked. Bottom: tan to rusty-brown with very small, uniform pores. The pore layer of the conk may cover a much greater area than the upper surface. Appears velvety when fresh. Inside: yellow- to rusty-brown with streaks of white mycelium.
Damage: White rot of the sapwood and heartwood of living trees. Incipient (early) decay appears as irregular patches of brown to purple discoloration. Advanced decay appears bleached and laminated on radial sections with brown zone lines. Decay is usually limited to the area just above and below the conk. Bark may appear sunken around conks when the sapwood is killed.
Remarks: Conks are difficult to remove from trees. Hartig’s conk is named after Robert Hartig, a 19th century German forest scientist regarded by many as the father of forest pathology.
Click the conk image to view full Fomitipora tsugina/Phellinus hartigii album on Flickr.
Echinodontium tinctorium (Ellis & Everh.) Ellis & Everh.
2024 Status/Activity: Surveys were conducted on Mitkof Island near the 2012 detection location, prior to which it was unknown to occur in Alaska south of Haines.
2024 Ground Detection Survey Observations: 3 on Mitkof Island and 1 near Girdwood.
2024 iNaturalist Observations: 1 near Girdwood.
In 2015, the paint fungus (Echinodontium tinctorium), thought to be absent in Southeast Alaska south of Skagway, was found to be locally abundant on western and mountain hemlock in one stand on Mitkof Island south of Petersburg following its initial detection in 2012. Continued survey work may allow us to detect this fungus in other locations.
Hosts: Western and mountain hemlock; occasionally spruce.
General Distribution in Alaska: Southeast and Southcentral Alaska.
Identification: Perennial, woody, hoof-shaped conk anywhere on bole. Forms as a parasite on living trees, usually on or under branch stubs or dead branches. Top: rough and cracked, dull black to dark grey. Bottom: grey-brown to black; thick, blunt spines or teeth. Inside: brick red to rust red or orange. The pigment extends into the adjacent wood.
Damage: Laminated stringy white rot, usually mid-trunk. Trunk may become completely hollow.
Remarks: Presence of conk indicates substantial heart rot. In Alaska, occurs in the northern Panhandle near Haines and Skagway and in south-central Alaska within the distribution of mountain hemlock. Identified at one location on Mitkof Island, so may be present elsewhere on the Panhandle. Traditionally used to prepare red paint pigments.
Click the image to view full Echinodontium tinctorium album on Flickr.
Laricifomes officinalis (Vill.) Kotl. & Pouzar (=Fomitopsis officinalis)
2024 Status/Activity: This fungus is infrequently encountered, generally on very large Sitka spruce trees. One conk specimen was collected last year, and notable regrowth had occurred one year later. This fungus can have the typical stacked growth form, or be more hoof shaped.
2024 Ground Detection Survey Observations: 3 near Ketchikan on Sitka spruce.
2024 iNaturalist Observations: 1 research grade observation near Sitka.
Hosts: Spruce (especially Sitka spruce), hemlock, larch, and shore pine.
General Distribution in Alaska: Southeast Alaska.
Identification: Rare. Perennial, woody, vaguely hoof-shaped to elongated-columnar conk. Usually occurs high on bole of living old-growth trees, but also persists for many years as a saprobe on dead trees. Top: zoned, white or yellow-white turning to grey or light brown with age, chalky coating, sometimes greenish with algae. Bottom: Convex, white when fresh with tiny round uniform pores, drying to light brown. Inside: white to grey, cheesy to chalky with age, distinctly bitter taste.
Damage: Early decay light yellow to red-brown. Advanced decay is a crumbly brown cubical rot. Thick, white, bitter-tasting mycelial felts may form in shrinkage cracks.
Remarks: A single fruiting body indicates extensive heart rot and hazard of tree failure. Conks have long been used in traditional medicine and show promise in modern research. Many cultures, including the Tlingit, have carved conks into shaman grave guardians.
|
Image
Quinine conk (Laricifomes officinalis, previously Fomitopsis officinalis) on Sitka spruce along the Stikine River. Photo Credit: USDA Forest Service photo by Karen Dillman |
Porodaedalea pini (Brot.) Murrill (=Phellinus pini)
2024 Status/Activity: Several hemlock failures were associated with P. pini near Girdwood this year. The snapped trees were also colonized by Armillaria root rot, common on stressed and recently killed trees.
2024 Ground Detection Survey Observations: 44 total, 11 from Anchorage, the Kenai Peninsula, and Cordova in Southcentral Alaska, and 33 from Haines to Ketchikan throughout Southeast Alaska. Host tree species included western hemlock (20), mountain hemlock (12), mountain hemlock (7), white spruce (2), Lutz spruce (1), black spruce (1), and shore pine (1).
2024 iNaturalist Observations: 15 total, 10 from Skagway, Haines, Juneau, and Sitka in Southeast, 4 from the Kenai Peninsula, and 1 from Denali State Park.
Although primarily considered a heart rot, P. pini can progress into sapwood and kill trees. Although more common in coastal forests, the range of P. pini extends into Interior Alaska. Multiple fruiting bodies along the length of the tree bole indicate extensive internal decay.
Hosts: Hemlock, spruce and shore pine; occasionally western redcedar.
General Distribution in Alaska: Most common on hemlocks in coastal forests but present throughout forested Alaska where hosts occur.
Identification: Perennial, woody, fan-, shelf-, to hoof-shaped conk. Occurs anywhere on bole of live or recently dead trees. Often associated with branch stubs. Top: reddish brown to dark brown with a narrow, velvety golden margin; usually zoned in concentric rings; becoming furrowed and rough. Bottom: yellowish brown to rusty brown, pores angular to nearly slot-like. Interior: bright rusty brown; corky to woody.
Damage: White pocket rot. Incipient (early) decay is a red stain in the heartwood that appears as a well-defined ring in cross-section. In advanced decay, small flecks of fungal mycelium are evident and once-separate areas of decay merge.
Remarks: Decay can progress from the heartwood to the sapwood and cause tree death.
|
Image
Porodaedalea pini on shore pine. Photo Credit: USDA Forest Service photo by Robin Mulvey |
Image
|
Click the image to view full Porodaedalea pini album on Flickr.
Laetiporus conifericola Burds. & Banik
2024 Status/Activity: Prolific fruiting was observed in many parts of coastal Alaska in 2023 (from Ketchikan to Kodiak Island and Katmai National Park) but returned to normal levels this year. The actual incidence of this fungus is similar from year to year, but conditions in some years support abundant fruiting. The iNaturalist application can be particularly helpful in cataloging the occurrence of popular, easily identified fungi, like the sulfur fungus, with ephemeral fruiting structures.
2024 Ground Detection Survey Observations: 11 total, 9 scattered throughout Southeast Alaska from Haines to Ketchikan, and 2 near Cordova. Of these, 8 records came from western hemlock, 2 from Sitka spruce, and 1 from an unknown conifer.
2024 iNaturalist Observations: 50 total, 37 from the Kenai Peninsula, Kodiak Island, and Katmai National Park, and 13 from Juneau, Sitka, Petersburg, and Prince of Whales Island in Southeast Alaska.
Hosts: Spruce and hemlock; occasionally shore pine.
General Distribution in Alaska: Coastal forests of Southeast and Southcentral Alaska.
Identification: Annual, shelving, in clusters, fleshy; usually on lower bole of conifers. Primarily saprobic on dead trees and stumps, but occasionally causes heart rot on living trees. Top: bright orange to yellow when fresh; crumbly white after it dies. Bottom: sulfur-yellow with small pores often in clusters. Inside: Yellow, watery, and soft when fresh; white and chalky or soggy after it dies.
Damage: Brown cubical rot, may have white mycelial felts.
Remarks: Edible when young, some think the conk tastes like chicken. Also called Sulfur Shelf fungus. The mycelial felts in decayed wood is somewhat similar to that of the quinine conk but do not taste bitter. Use caution when harvesting fungi for consumption.
Click the image to view full Laetiporus conifericola album on Flickr.
Ganoderma tsugae Murrill
Ganoderma oregonense Murrill
2024 Status/Activity: Based on spore size measurements, all specimens collected in Southeast Alaska have been identified as Ganoderma oregonense, rather than G. tsugae, which is now thought to be restricted to hemlock hosts in eastern North America (Loyd et al. 2018, PLoS ONE 13(7): e0199738. https://doi.org/10.1371/journal.pone.0199738). Anecdotally, this fungus is more abundant in the southern half of Southeast Alaska. This year, the fungus fruited prolifically, especially near Ketchikan.
2024 Ground Detection Survey Observations: 9 from Southeast Alaska near Juneau, on Mitkof Island, and near Ketchikan on Revillagigedo Island.
2024 iNaturalist Observations: 18 research grade records from Juneau, Hoonah, Sitka, Revilla Island, and Metlakatla.
Hosts: Western hemlock; occasionally other conifers.
General Distribution in Alaska: Southeast Alaska.
Identification: Annual, shelf or fan-shaped conk. Usually saprobic on large, old stumps or logs. Top: surface distinctly varnish-like and shiny reddish brown, at first knobby or elongated becoming somewhat fan-shaped. Bottom: white pore surface, becoming brownish with age. Usually bruises brown. Pores minute. Stalk: lateral (from side), varnished reddish brown, sometimes absent.
Damage: White rot decay appears wet, spongy, soft, straw-colored or white in the butt or stem. May have large black spots scattered throughout.
Remarks: Also called lacquer conk or (a relative of) Reishi, this group of fungi have long been used in traditional medicine; modern research has shown potential medicinal benefits, including wound healing and anti-tumor activity in mice.
Click the image to view full Ganoderma tsugae album on Flickr.
Additional Information
Stem decays occur on conifer hosts throughout the state, but have been studied in greatest depth in Southeast Alaska. Stem decay incidence changes little over time without active management. In mature forests of Southeast Alaska, conifer stem decays cause enormous wood volume loss. Approximately one-third of the old-growth timber volume in Southeast Alaska is defective, largely due to stem decay. There is very little decay in young-growth stands unless there is prevalent wounding. Stem decays are key disturbance agents in the coastal rainforest, because they predispose large old trees to bole breakage and windthrow. Stem decays create canopy gaps, influence stand structure and succession, perform essential nutrient-cycling functions, increase biodiversity, and enhance wildlife habitat. Trees with stem decay can be hazardous in managed recreation areas. Visit our hazard tree management webpage. Brown rots are the most significant source of cull for Sitka spruce, while white rots are most significant for western hemlock and western redcedar. Western redcedar is the most defective species, followed by western hemlock and Sitka spruce. A variety of different fungi cause stem decay in Alaskan conifers.
This table displays the most common conifer stem decays in Alaska, with information about the type of decay they cause, their tree hosts, modes of infection and known distributions in Alaska. For some conifer stem decay fungi, we have enough georeferenced ground observations to provide maps of detection locations.
Stem decays rot or deteriorate wood, primarily in tree trunks, rather than roots and butts. They can be identified based on the presence and characteristics of conks, mushrooms, or other fungal structures on tree boles, when present. The characteristics of decayed wood and species of host tree can also be helpful for identification. Wildlife holes, cavities, and hollows indicate the presence of stem decay on live trees, even when conks and mushrooms are absent. Heart rot develops primarily in the heartwood (inner wood) of living trees, whereas sap rot develops in the sapwood (outer wood beneath bark) and is usually extensive only in dead trees. Bole wounds and cracks provide entry points for many stem decay fungi, although some decays enter through natural openings like branch stubs.
Brown rots are particularly detrimental to tree strength. They degrade cellulose fibers leaving behind brownish lignin, which dries in brittle cubes. White rots decompose all wood components (cellulose and lignin); wood remains fibrous until very late stages of decay. The color and texture of white rots is dependent upon the causal fungi.
By predisposing large old trees to bole breakage and windthrow, stem decays are key disturbance agents. Individual tree mortality, much of it caused by heart rot fungi, creates small-scale canopy gaps and appears to be the leading form of disturbance in the coastal rainforest (Hennon 1995), where fire and other large-scale disturbances are uncommon. All major tree species in Southeast Alaska have been found killed in this manner. Stem decays influence stand structure and succession, perform essential nutrient cycling functions, increase biodiversity, and enhance wildlife habitat. Heart rot has an obvious and essential role in wood decomposition and has been demonstrated to be a site of nitrogen fixation by other microorganisms. Cavities created by stem decay fungi in standing trees provide crucial habitat for many species (bears, voles, squirrels and birds). Stem decays reduce merchantable timber volume from mature harvest units (especially old-growth) and can be hazardous in managed recreation areas. Many stem decay fungi cause heart rot of living trees, others decay the wood of dead trees, and some grow on dead tissue of both live and dead trees. Most of these decays do not actually interfere with the normal growth and physiological processes of live trees since the vascular system is unaffected. However, some decay pathogens, such as Phellinus hartigii and P. pini may attack the sapwood and cambium of live trees after existing as a heart rot fungus. Many of the fungi that are normally found on dead trees (e.g., Fomitopsis pinicola) can grow on large stem wounds, broken tops and dead tissue of live trees. Root and butt rot fungi can also cause stem decay in the lower bole (e.g., Phaeolus schweinitzii).
Wounds on live trees caused by logging activities are potential sites of infection for decay fungi to cause appreciable timber losses (Wright and Isaac 1956). Generally, larger, deeper wounds and larger diameter breaks in tops result in a faster rate of decay (Hennon 1990). Without logging injury, heart rot in young forests are typically at very low levels until stand age 100 to 150 years. Eventually, heart rot consumes as much or more wood volume annually than is produced by the live trees. There are methods that could be used to promote earlier development of stem decays for wildlife habitat in young-growth stands with non-timber objectives (Filip et al. 2011, Hennon and Mulvey 2014), such as intentional bole wounding and top breakage during stand entries. In some instances, bole breakage can be encouraged to occur in a specific direction (e.g., across steams for coarse woody debris input) by causing wounds to one side of the bole (e.g., the side that faces the stream).
Our knowledge of stem decay impacts on timber volume loss primarily come from two cull studies in Southeast Alaska (Kimmey 1956 and Far et al. 1976). A study by Hennon and McClellan (2003) evaluated modes of tree mortality (e.g., died standing, broken bole, uprooting) in old-growth forests. Permanent monitoring plots throughout Southcentral and Interior Alaska (evaluated 2013-2016) are helping to build information about the distribution and relative importance of stem decays on various tree hosts in other regions and forest types in Alaska.
An important cull study conducted by James Kimmey in Southeast Alaska in the 1950s found that brown rots were the most significant source of cull for Sitka spruce, while white rots were most significant for western redcedar (especially Obba/Ceriporiopsis rivulosa and Phellinus weirii) and western hemlock. Farr et al. (1976) found similar high rates of decay in old-growth forests as Kimmey (1956). These and other studies have shown that stem decay incidence and volume increase with tree size. The amount of defect also depends on tree species: for any given size or age class, redcedar was the most defective species, followed by western hemlock and Sitka spruce. Although redcedar wood products are known for decay resistance, it seems that a few species of decay fungi are specialized to overcome the decay resistance of live redcedar but do not affect wood in service.
Farr, W. A.; LaBau, V. J.; Larent, T.L. 1976. Estimation of decay in old-growth western hemlock and Sitka spruce in southeast Alaska. Research Paper PNW-204. Portland, OR: U.S. Department of Agriculture, Forest Service. 24 p. Available to download here.
Filip, G.; Chadwick, K.; Zambino, P.; and others. 2011. Seven- to 12-year effects of artificially inoculating living conifers to promote stem decay and subsequent wildlife use in Oregon and Washington forests. Portland, OR: USDA Forest Service, Forest Health Protection. Available here.
Hennon, P. E. 1990. Wounding on residual Sitka spruce and western hemlock remaining after thinning on Prince of Wales Island, Alaska. USDA Forest Service, State and Private Forestry, Juneau, AK. Forest Pest Management Report R10 90 2. 9p. Available here.
Hennon, P. E. 1995. Are heart rot fungi major factors of disturbance in gap-dynamic forests? Northwest Science. 69: 284-293. Available here.
Hennon, P.E.; McClellan, M. H. 2003. Tree mortality and forest structure in temperate rainforests of southeast Alaska. Canadian Journal of Forest Research 33: 1621-1634.
Hennon, P. E.; Mulvey, R. L. 2014. Managing heart rot in live trees for wildlife habitat in young-growth forests of coastal Alaska. Gen. Tech. Rep. PNW-GTR-890. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 23 p. Available here.
Kimmey, J. W. 1956. Cull factors for Sitka spruce, western hemlock, and redcedar in southeast Alaska. USDA Forest Service. Alaska Forest Research Center, Juneau, Alaska. Station Paper No. 6. 31p. Available here.
Kimmey, J. W. 1964. Heart Rots of Western Hemlock. USDA Forest Pest Leaflet 90. Available here.
Wright, E.; Isaac, L. A. 1956. Decay following logging injury to western hemlock, Sitka spruce, and true firs. USDA Tech. Bull. No. 1148. 34p. Available here.
Pocket guide for the identification of common forest diseases and insects in Alaska.
Content prepared by Robin Mulvey, Forest Pathologist, Forest Health Protection, robin.mulvey@usda.gov