How to Manage Pests

Pests in Gardens and Landscapes

Wood Decay Fungi in Landscape Trees

Revised 8/19

In this Guideline:

  • Damage
  • Identification and biology
  • Management
  • About Pest Notes
  • Publication
  • Glossary

White rot of oak.

Heart brown rot in a conifer trunk.

Fruiting bodies of turkey tail fungus.

Wounds where large avocado limbs were pruned have been colonized by a heart rot decay fungus.

Several fungal diseases, sometimes called heart rots, sap rots, or canker rots, decay wood in tree trunks and limbs. Under conditions favoring growth of specific rot fungi, extensive portions of the wood of living trees can decay in a relatively short time (i.e., months to years). Decay fungi reduce wood strength and may kill storage and conductive tissues in the sapwood. While most species of woody plants are subject to trunk and limb decay, older and weaker trees are most susceptible.


Decay fungi destroy cell wall components; including cellulose, hemicellulose, and lignin, that make up the woody portion of a tree. Depending on the organism, decay fungi can destroy the living (sapwood) or the central core (heartwood) part of the tree. Decay isn’t always visible on the outside of the tree, except where the bark has been cut or injured, when a cavity is present, or when rot fungi produce reproductive structures.

Wood decay can make trees hazardous, as infected trunks and limbs become unable to support their own weight and fall, especially when stressed by wind, heavy rain, or other conditions. Decay can also be hidden, affecting wood strength without any outward sign of its presence. Decay fungi typically reduce the weight of wood by growing through the vascular tissues and degrading some or all major cell wall components and absorbing breakdown products of cellulose or hemicellulose. A 10% loss of wood weight can result in 70 to 90% loss in wood strength. Many branches that fall from trees appear sound, but upon analysis, they were colonized by wood decay organisms.

Table 1 lists several wood decay fungi found on California trees and symptoms and signs commonly associated with each organism.

How to remove a branch or limb

Remove a branch by making the pruning cut just outside the branch bark ridge and branch collar, as indicated by number 3. When removing a limb larger than about 2 inches in diameter, make three cuts in the order indicated. Make the first cut from below, about one-third of the way through the limb and 1 or 2 feet from the trunk. Make the second cut about 2 inches beyond the first cut, cutting from above until the limb drops. Make the final cut at number 3.


Many wood decay fungi can be identified by the distinctive shape, color, and texture of the fruiting bodies they form on trees. These fruiting bodies take several forms, depending upon the fungus that produces them, but most of them fit into categories commonly referred to as mushrooms, brackets or conks. They often grow near wounds in bark, including old pruning wounds, at branch scars, in proximity to the root crown, or near surface anchor roots. Some decay fungi, such as Armillaria mellea, produce fleshy mushrooms at the base of infected trees or along their roots, often after rain in fall or winter. All mushrooms and some bracket fungi are annual (i.e., appearing and disappearing seasonally), but many conks are perennial and grow by adding a new spore-bearing layer (hymenium) each year.

Decay fungi are divided into those that attack heartwood (causing heart rots) and those that attack sapwood (causing sap rots and canker rots). Further subdivision is based on the appearance of the decayed wood (i.e., white rots, brown rots, and soft rots) or location in the tree (the decay is called a butt rot if it is at the base of the trunk). Canker rots usually appear on branches or the trunk. When a fruiting body is visible on a tree, it is usually associated with advanced decay; the extent of decay may be far above or below the location of the fruiting body. Trees with extensive sap rot may show symptoms of decline, including increased deadwood and a thinning canopy with reduced density of foliage.

White rots

White rots break down lignin and cellulose, and commonly cause rotted wood to feel moist, soft, spongy, or stringy and appear white or yellow. Mycelia colonize much of the woody tissues. White rots usually form in flowering trees (angiosperms) and less often in conifers (gymnosperms). Fungi that cause white rots also cause the production of zone lines in wood, sometimes called spalted wood. This partially rotted wood is sometimes desirable for woodworking.

Brown Rots

Brown rots primarily decay the cellulose and hemicellulose (carbohydrates) in wood, leaving behind the brownish lignin. Wood affected by brown rot usually is dry, fragile, and readily crumbles into cubes because of longitudinal and transverse cracks occurring which follow cellular lines, or across cells, respectively. The decay commonly forms columns of rot in wood. Brown rots generally occur in conifers as heart rots. Hardwood trees are more resistant to decay by brown rot than to white rot fungi.

Soft Rots

Soft rots are caused by both bacteria and fungi. These organisms break down cellulose, hemicellulose, and lignin, but only in areas directly adjacent to their growth. Soft rot organisms grow slower than brown or white rot organisms, and therefore damage occurs to the host tree more gradually. Given enough time, however, any rot can cause extensive structural damage.


Most wood decay in limbs and trunks is the result of infection by airborne fungal spores and by spores and mycelial fragments carried by insects to wood exposed by injury. Injuries include natural branch thinning and loss due to shading, pruning wounds, vandalism, and damage from machinery or construction. Other causes of wounds include sunburn, fire, ice, lightning, snow, or insects that bore into the trunk or branches. Some decay organisms can enter through natural openings in the stem such as lenticels or at branch unions. Armillaria mellea and Ganoderma spp. commonly infect woody roots and can spread to nearby trees through root grafting.


Wood decay is usually a disease of old trees. While difficult to manage, several factors can reduce its impact. Protect trees from injuries and provide proper cultural care to keep them vigorous. Prune young trees properly to promote sound structure and minimize the need to remove large limbs from older trees, which creates large wounds. Large wounds provide greater surface area and exposure to heartwood for potential colonization by decay organisms.

Remove dead or diseased limbs. Make pruning cuts properly. Prune just outside the branch bark ridge, leaving a uniform collar of cambial tissue around cuts on the trunk to facilitate wound closure. Avoid leaving stubs (branch protrusions that will eventually die) that provide an infection opportunity due to wound closure failure. Proper pruning cuts are circular, not oval, and not flush to the main stem (which damages the branch bark collar or ridge). Wound dressings are not recommended as they do not hasten wound closure or prevent decay and, in some cases, may hasten the development of decay behind the dressing.

Tree failures can cause personal injury, property damage, or both. Trees near structures or other high-value potential targets should be regularly inspected by a qualified expert for signs of wood decay and other structural weakness. Hazardous trees should be assessed by a qualified arborist who can recommend mitigation, including appropriate pruning or cultural practices. Depending on the extent of decay and the structural weakness, tree removal may be necessary.

Table 1. Wood Decay Fungi on California Landscape Trees.

Fungus Common hosts Symptoms
Armillaria mellea
oak root fungus
Many coniferous and broadleaved woody species; peach, fig (F. carica) and Peruvian pepper are highly susceptible hosts.

One of the most widespread plant pathogens in California. Causes a white butt and root rot. When bark is removed, white or cream-colored mycelial plaques—the vegetative part of fungi—are present between the bark and wood of roots and trunk near or slightly above the soil line. Mushrooms can form at the base of affected trees following fall and winter rains. Fungi enter susceptible plants by means of dark, rootlike structures called rhizomorphs found on the surface of affected roots. Fungal growth is most rapid under warm and wet conditions; decay has been slowed or stopped in some instances by removing soil from around the base of the tree and allowing areas to dry.

Ganoderma applanatum
artist’s conk

Wide variety of landscape and forest trees including acacia, alder, ash, birch, carob, citrus, elm, eucalyptus, fir, magnolia, maple, mulberry, oak, Peruvian pepper tree, pine, poplar, sweet gum, sycamore, tulip tree, and willow.

The fungus invades trees through wounds, kills the sapwood of some species, and causes white rot of the sapwood and heartwood in roots and trunks. Forms semicircular conks that are 2–30 inches wide and 1–8 inches thick. Upper surface of conk is brown, and the lower surface is white, but turns dark when scratched, hence the common name “artist’s conk.” Stalks are absent. Fungus can spread through natural root grafting. Conks usually are found near ground level. Columns of decaying wood can extend as far as 15 feet above and below the conk.

Ganoderma polychromum (formerly G. lucidum)
varnish fungus
Acacia, apple, ash, birch, boxwood, cherry, citrus, elm, hackberry, sweet gum, black locust, honey locust, magnolia, maple, oak, olive, peach, Peruvian pepper tree, pine, poplar, redbud, spruce, and willow. The fungus causes a white rot and can attack living trees, causing extensive decay of roots and the trunk. Can kill the host during a period of 3–5 years. On some trees, such as oaks and maples, the rate of decay is rapid. The red-brown, annual conks are up to 14 inches wide and coated on top with a distinctive reddish varnish-like crust; they generally appear at base of the trunk during summer. Causes decline in hardwood trees. Environmental stress, such as drought and wounding, can predispose trees to infection from this fungus.
Laetiporus gilbertsonii
L. conifericola
sulfur fungus
Acacia, ash, beech, birch, cherry, chestnut, elm, eucalyptus, fir, hackberry, black locust, honey locust, maple, oak, pepper tree, pine, poplar, spruce, tulip tree, walnut, and yew.

The fungus causes a brown heart rot of living trees but also will decay dead trees. It is one of the few brown rot fungi of hardwood trees. It can enter trees through bark wounds and dead branch stubs. This fungus is one of the most serious causes of decay in oaks and eucalyptus, and one of the few fungi that cause decay in yew. The soft, fleshy, moist conks range from 2 inches to over 20 inches wide and are bright orange yellow above and red yellow below. Conks are produced annually and appear singly or in clusters, usually in fall; they become hard, brittle, and white with age. Conks do not appear until many years after the onset of decay and indicate extensive internal damage.

Pleurotus ostreatus
oyster mushroom
Acacia, alder, ash, beech, birch, chestnut, elm, eucalyptus, fir, hackberry, holly, horse chestnut, linden, magnolia, maple, oak, olive, pecan, persimmon, poplar, spruce, tulip tree, walnut, and willow.

This fungus decays heartwood and sapwood, causing a white, flaky rot. Infections occur through open wounds, and decay is most extreme when wounds are large. A cluster of shelf-like mushrooms, each 2–8 inches wide, is produced annually and can indicate localized decay or heart rot that extends 10 feet in either direction. The mushrooms are smooth on the upper surface with gills that characteristically extend down along the stalk on the lower surface.

Schizophyllum commune
common split gill fungus
More than 75 species of landscape trees including acacia, ash, birch, camphor, elm, eucalyptus, fir, juniper, laurel, locust, magnolia, oak, oleander, pepper tree, pine, plane tree, poplar, sequoia, spruce, sweet gum, tulip tree, walnut, and willow. This fungus causes a white rot of sapwood and produces annual fruiting bodies that are hairy and white to pale brown when young but darken with age. The stalkless brackets are tough, leathery, about 1–4 inches wide, and usually found in clusters. The pale gills on the underside have the appearance of being longitudinally split, hence the common name. The fungus colonizes trees stressed by heat, sunburn, drought, or major wounds. It generally fruits on cut and fallen wood and dead parts of living trees.
Stereum species
parchment fungus
Acacia, alder, birch, catalpa, cherry, chestnut, elm, eucalyptus, fir, juniper, magnolia, maple, oak, pine, sequoia, spruce, sweet gum, tulip tree, and willow. This group of fungi are commonly found on dead trees, branches, and stumps but rarely cause serious decay in living trees. They can cause heart rot on trees wounded by pruning or bark injury. The annual fruiting bodies are thin, leathery, and bracket-like, lack stalks, and are 1 inch or more across. The upper surface is gray brown, and the lower side is buff to brown and smooth, lacking tubes or pores.
Trametes hirsuta
hairy turkey tail fungus
Alder, ash, birch, catalpa, cherry, chestnut, citrus, elm, eucalyptus, fir, ginkgo, holly, juniper, locust, magnolia, maple, oak, pine, poplar, redbud, spruce, sweet gum, sycamore, tulip tree, walnut, and willow. This fungus, which causes white rot, can enter a tree through dead wood exposed by fire scarring; decay begins as a sap rot and can continue as a heart rot on some woody species. It often produces fruiting bodies on the dead portions of live hardwoods; fruiting bodies are tough, leathery, usually stalkless, shelf-like, and 1–10 inches wide. The outer surface is dry, velvety, and has concentric zones. The under surface is poroid.
Trametes versicolor
turkey tail fungus
Alder, apple, ash, beech, birch, catalpa, cherry, chestnut, crape myrtle, elm, eucalyptus, fir, gingko, hackberry, holly, juniper, laurel, lilac, linden, locust, London plane tree, maple, nectarine, oak, pepper tree, poplar, redbud, sweet gum, tulip tree, walnut, and willow.

This fungus commonly is found on cut and fallen wood and on wounded areas of living trees; it also is capable of colonizing sapwood of trees and shrubs stressed by water shortage, sunburn, freeze damage, or wounding. The fungus, which causes a white, spongy rot of wood, can actively invade and rapidly kill the cambium (the tissue between the bark and wood), causing cankers with papery bark and dieback. The annual conks are thin, leathery, stalkless, bracketlike, 1–4 inches across, and often found in groups. The upper surface is velvety with concentric zones of various colors, and the lower surface is cream colored and minutely poroid.

Phellinus igniarius and other Phellinus spp.

American sweetgum, apple, bay tree, birch, elm, cottonwood, locust, lilac, poplar, pear, walnut, oak, sycamore, willow.

Phellinus produce perennial conks with a “hoof” like appearance—dark and cracked above and tan or ochre below, with small pores. A new hymenium or spore bearing layer is added each year. These are white rotting fungi that are common on various species of hardwoods and softwoods. These cause heart rots on intact trunks.

Biscogniauxia mediterranea, B. atropunctata Sycamore, oaks, maple, pecan, golden raintree, ash, walnut.

Biscogniauxia is an Ascomycete fungus that resides in trees as a latent infection not causing symptoms. When trees are stressed by drought, the fungus invades the sapwood, decaying it extensively and cutting water supplies to the canopy. Fruiting bodies are long sheets of charcoal-like stroma that emerge through and from under the bark of affected hardwoods. Conidia proceed the dark charcoal sexual fruiting bodies.

Annulohypoxylon spp. Coast live oak, maple, alder, birch, apple, cottonwood, willow, elm, persimmon, mountain lilac.

Annulohypoxylon spp. are in the same group as Biscogniauxia but fruiting bodies form on the surface of bark in a concentric- or globe-shaped stroma. They only form on dead wood and indicate that the sap rot fungus has killed that portion of the standing tree. The young fruiting bodies are cream-colored and covered in asexual spores called conidia in early summer or late spring. These later darken into structures that contain the sexual ascospores.

Oxyporus latemarginatus Victorian box, coast live oak, maples, albizia, citrus, ash, locust, walnut, American sweetgum, magnolia, apple, cottonwood, peach, plum, apricot, willow, and elm. This fungus produces its white poroid fruiting body covering the lower portions of trees sometimes spreading over soil around the root collar. It is annual and disappears a few weeks after its occurrence. It is a potent sap rot fungus that leads to extensive white rot, sometimes colonizing the entire trunk.


Dreistadt SH, Clark JK, Martin TL, Flint ML. 2016. Pests of Landscape Trees and Shrubs 3rd Edition. UCANR Publication 3359. Oakland, CA.

Farr DF, Bills GF, Chamuris GP, Rossman AY. 1995. Fungi on plants and plant products in the United States. St. Paul: APS Press.

Loyd AL, Barnes CW, Held BW, Schink MJ, Smith ME, Smith JA, Blanchette RA. 2018. Elucidating “lucidum”: Distinguishing the diverse laccate Ganoderma species of the United States. PLoS ONE 13(7) (accessed June 24, 2019).

Schwarze FWMR. 2007. Wood decay under the microscope. Fungal Biology Reviews. (accessed June 24, 2019).

Vasaitis R. 2013. Heart rots, sap rots and soft rots. P Gontheir and R Nicoletti (eds.). Infectious Forest Diseases. CAB International.


Pest Notes: Wood Decay Fungi in Landscape Trees

UC ANR Publication 74109

AUTHORS: A. James Downer, UC Cooperative Extension, Ventura County, and Edward J. Perry, UC Cooperative Extension (retired), Stanislaus County.
EDITOR: B Messenger-Sikes

Produced by University of California Statewide IPM Program

PDF: To display a PDF document, you may need to use a PDF reader.

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Tree Diseases: Artist’s Conk (Ganoderma applanatum)


Artist’s conk (Ganoderma applanatum), also referred to as artist’s bracket, red mother fungus, Ancient Ling Zhi, and bear bread fungus, is a bracket fungus that infects a bevy of trees. In Japan, the fungus is known as kofuki-saru-no-koshikake, which translates to “powder covered monkey’s bench.” It is called shu-she-ling-zhi in China. Artist’s conk is a polypore: it achieves sporulation through pores instead of gills. The fungus has an ascending, shelf-like appearance that distinguishes it from other polypores. Artist’s conk is initially parasitic. Once the host expires, the fungus becomes a saprotroph, decaying the remaining organic tissue.

Distribution & Habitat

Artist’s conk occurs globally, wherever susceptible trees are present.


Artist’s conk infects most hardwoods, and many conifers. It is most common on alder, ash, beech, Douglas-fir, elm, poplar, buckeye chestnut, horse chestnut, maple, walnut, willow, western hemlock, olive tree, and spruce. Older trees and trees suffering from environmental stressors are more susceptible to infection.

Disease Cycle

The fungal spores infiltrate trees through bark injuries, branch stubs, and other wounds. Fruiting bodies form on the trunks of infected trees. When they first appear, the fruiting bodies are white. As they mature, the fruiting bodies turn a dark reddish-brown. The fruiting bodies are fan to hoof shaped, with a hard exterior. They are perennial, and may persist for years, increasing in size, and forming new layers as they develop.

Artist’s conk causes a white to yellow rot of the sapwood and heartwood. Over time, the decay will become extensive, rendering the tree prone to failure. Sporulation typically occurs in spring and fall, when conditions are sufficiently moist. The spores are dispersed by air currents, splashes of rain, or insect vectors to nearby trees, which they readily infect. If conditions are favorable, infections can be induced all year.

Symptoms of Infection

The fruiting bodies are conspicuous on infected trees. They can measures 12 to 40 inches in diameter, and may be observed on infected tree trunks and stumps. When plucked from infected trees, the fruiting bodies will reveal layers of pores that resemble rings.


The fruiting bodies are inedible in their raw form. However, when cooked, they have a rich mushroom flavor that blends well with various recipes. Slices of the fruiting bodies have been used in fermented foods to enhance their flavor. When dried and ground, the fruiting bodies can be made into a tea or tincture. Artist’s conk can be used for dyeing wool, certain fabrics, and paper. In Asia, the fruiting bodies are blended or cold pressed with water to create ganoderma drinks.

Artist’s conk contains antibacterial compounds. As such, it is often used in traditional medicines. If rubbed or scratched with a pointed utensil, artist’s conk bruises. The bruises become permanent once the fungus has dried. This makes the fungus an ideal platform for artists to paint or sketch intricate designs on. The midge Agathomyia wankowiczii lays its eggs on the fruiting bodies. The forked fungus beetle, Bolitotherus cornutus, dwells within the fruiting bodies for its entire life cycle.


  • Maintain trees through sound cultural practices. Ensures that trees are sufficiently watered. Each year, apply fresh organic mulch around the base of trees. Proper mulching will help to improve the soil quality, moderate the soil temperature, and retain soil moisture.
  • Avoid mechanical injuries to potential hosts.
  • Prune broken or damaged branches. Provide maintenance to trees that are overgrown. Periodically thin out tree canopies to increase air circulation, and promote a rapid drying of the foliage.
  • Culling infected trees may prevent the fungus from spreading, and achieve some control.

If you have any questions about artist’s conk, or you are interested in one of our tree services, contact us at 978-468-6688, or [email protected] We are available 24/7, and can accommodate any schedule. All estimates are free of charge. We look forward to hearing from you.

Shelf Fungi

Woody Shelves

Woody shelves may be several years old. They add a new layer of spore tissue every growing season. The old layer is covered by the new one. These layers look like growth rings in a tree. One author reported counting 37 rings. Ten layers may mean the shelf is 10 years-old if there is only one growing season (spring). If there are two growing seasons per year (spring and fall), it may only be 5 years-old.
One of the largest shelves weighs 300 pounds. Unfortunately, it isn’t known how many growth layers it contains. Woody shelves are a micro (small) habitat. They provide a unique place for animals to live. Spiders, mites, and insects live in large shelves. A few of the insects are specialized and only found in shelf fungi. Some beetles are very slim so they can fit inside a pore. They hide in a pore and eat spores. There are enough insects and other animals that a food web is created. The spiders and some insects are predators that feed on other insects. Their prey include fly larvae and small insects.
Woody shelves are impossible to break with your hands and difficult to cut. This toughness results from the kinds of hyphae (filaments) that are used to construct the shelf. Easily crushed mushrooms are made of thin-walled hyphae. Some of the hyphae in woody shelves are thick-walled and the hyphae are interwoven making them tougher. They resist tearing or splitting because there are no planes to split along in the tissue.

Although some of them can be quite beautiful, the appearance of shelf fungi coming through the bark of a tree is a bad sign indeed. These “mushrooms” are actually the fruiting body of a fungus. When they are present, they mean that a rotting fungus is growing on the inside of the tree. The shelf fungi stick their heads out into the open so that they can cast spores into the air to go and infect other trees.

When the shelf fungi are located near ground level, it often means that an extensive amount of root rot is active. This is bad news since it means at least two things. One is that the tree is losing vigor since it is surviving on a root system of decreased size. There are probably stems and branches that have either died or will die due to the lack of roots to provided needed water.

The other warning indicated by shelf fungi is that the tree is now less stable than it would be if it were totally healthy. Root rots may either cause the death of roots or, more likely, they are just helping to decompose roots that have already died for some other reason such as soil compaction, nearby construction or just the advanced age of the tree. Either way, one of the roles of roots is to provide an anchor for the plant. When they are gone, the tree is more likely to fall over in an ice storm or on a windy day.

What can you do about shelf fungi? The practical answer is…nothing. They are a sign that the tree is in serious trouble and probably has been for a long time. By the time they show up, there is little chance of rejuvenating the root system to change the course of events.

Usually, all you can do is try to evaluate what damage the tree might do if it falls over in a storm…actually, I have seen ones that fell over on a nice, calm summer day too. Will it fall onto your house or some other valued part of the property such as a shed or backyard pond. Will it possibly be dangerous to people who might be in the area?

Nobody can predict exactly when a tree will come down. All you can say is that the presence of the shelf fungi increases the probability that it will come down sooner than would a similar, healthy tree.

There are people called Certified Arborists in most communities who, for a fee, will come and evaluate your tree. In the end, the best advise is probably to play it conservatively, have the tree cut down and avoid potential disasters. Why take the risk?


Tree decay fungi – Identification and Significance

The Kingdom of fungi is vast, fungi play vital roles in many ecosystems and are crucial to the lifecycles of many plant species on this planet. Connections between fungi and trees are often critical in determining tree vitality and stability.
Fungi can be put into three groups distinguished by how they feed:
Symbiotic or Mycorrhizal fungi live in association with many vascular plants’ root systems, and a beneficial exchange takes place between the two. The fungi will have almost constant access to the trees carbohydrate stores, in return benefiting the trees ability to absorb water and minerals with its structure of highly absorbent mycelium, effectively expanding the root system of the host plant
One of the most notable relationships we have of this kind is that of the Fly Agaric (Amanita muscaria) with the Silver Birch (Betula pendula)
Saprophytic fungi live on dead organic matter. This group of fungi will usually only take advantage of dieback caused by a separate factor, e.g. drought, rather than being the cause of decline themselves. While their role in the woodland ecosystem is every bit as important as that of the symbiotic, they are not so good to see on amenity trees. They may not kill trees but can ultimately cause mechanical failure.
A common and easily distinguishable saprophytic fungus is the Birch Polypore (Piptoporus betulinus)
Parasitic fungi live off or at the expense of their live host plant, often resulting in the demise of this host. In general these fungi will only target already unhealthy or stressed plants. No bad thing in the woodland ecosystem as it makes way for regeneration, but again not good for amenity trees.
While parasitic fungi on the whole blend in with everything else happening around us, from time to time they have had catastrophic consequences. There can be no better memorable example than the near end of elm trees due to Dutch elm disease in the 1970’s. This was thanks to the microscopic Ophiostoma novo-ulmi fungus.
The most prevalent of the parasitic fungi that also happens to be noticeably saprophytic is Honey Fungus (Armillaria mellea)
The fungi in these three groups each have very different implications and in some cases, end results for their hosts. To follow is a list that we will try to add to on a regular basis.
You will find the fungi listed by order of the month they are seen, starting late summer when most fungi will begin to fruit and finishing with the perennial brackets.

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List of Common Tree Decay Fungi

Including Habitat, Common Fruiting Season, Strategy, and Significance

Chicken of the woods (Laetiporus sulphureus)

Description: Notable annual from its early stages as a bright yellow knobble on the trunk growing to a group of uneven shelf like brackets from 10-60cm across. The soft, thick yellow flesh will darken to orange before drying and hardening to white in a period of a few weeks, then persist sometimes until the following year. Spores exuded from pores giving a white spore print.

(Photograph taken in August)

Habitat: Common on willow (as photo), oak, yew, cherry and sweet chestnut anywhere from the base of the trunk up to about 15ft

Season: Summer to autumn

Strategy: Saprophytic, causing a brown cubical rot of the heartwood

Significance: Affected wood at risk of brittle fracture

Notes: Edible when young and fresh

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Fly Agaric (Amanita muscaria)

Description: Notable annual, appearing first as a cracked white sphere before flattening to 8-20cm across by which time the fleshy cap will be bright red covered in distinctive white warts. These will be washed off by rain leaving a smooth fading skin. Fleshy white stem 8-20cm. Spores exuded from gills giving a white spore print

Habitat: Generally with birch and pine trees, occasionally others

Season: Autumn

Strategy: Mycorrhizal

Significance: Beneficial to host species. Can help prevent colonization of parasitic species such as Armillaria

Notes: Common. Poisonous, hallucinogenic. Photograph taken October

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Oak Bracket (Inonotus dryadeus)

Description: Annual bracket ranging from 10-70cm across. Pale when young, usually with droplets of clear to brownish liquid that seep from tubes on top. The flesh is reddish brown, hard and fibrous. The bracket will darken after several weeks, before turning black and cracked but remaining on the tree for a year or more. Spores exuded from pores leaving an off-white spore print

Habitat: The base of trunks of oaks

Season: All year though most often late summer

Strategy: Parasitic and saprophytic to oak trees causing triangular white rot, starting with decay of lignin around roots and base
Significance: Eventual ductile fracture at point of decay

Notes: Locally common. Not edible. Photograph taken September

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Birch Polypore (Piptoporus betulinus)

Description: Annual bracket ranging from 10-10cm across. Roughly spherical and pale when young, expanding to a semi-circular pale brown bracket and persisting for a year or more, by which time usually found blackened. The flesh is white and rubbery. Spores exuded from pores leaving a white spore print

Habitat: Usually dead birch trunks and branches, but occasionally found on living hosts.

Season: All year

Strategy: Parasitic causing brown cubicle rot. Persisting as a saprophyte once the tree has died.
Significance: Brittle fracture at point of decay, and usually the demise of a birch tree.
Notes: Enters wounds in healthy trees or may be present and dormant within vascular system from seed, but usually only becomes active when trees are stressed or in decline Very common. Not edible. Photograph taken February

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Porcelain fungus (Oudemansiella mucida)

Description: Grows in groups. Young greyish bell shaped cap will flatten and whiten to 3-10cm across, slimy on top. Scaly grey stem 3-10cm long, white and lined above the membranous ring. Flesh is white. Spores exuded from white gills leaving a white spore print

Habitat: Generally high up on beech, dead trunk or branches

Season: Late summer to late autumn

Strategy: Saprophytic, white rot localised to dead wood
Significance: Ductile fracture leading to eventual failure of affected parts
Notes: Common. Edible once gluten is removed. Photograph taken October

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Inonotus hispidus

Description: Annual bracket ranging from 6-25cm across. Red to brown and velvet-like on top and usually growing independently. The bracket will blacken with age and finally drop off within the year, remaining on the ground below the tree for a long time. Spores exuded from red to brown pores
Habitat: Commonly between 10-20ft on the trunks of ash, but sometimes seen on walnut, apple and London plane
Season: Summer, but evident on the tree or below it usually all year
Strategy: Parasitic causing simultaneous white rot
Significance: Brittle fracture at point of decay. The likelihood of standing wood being created is fantastic for biodiversity
Notes: Common. Not edible. Photograph taken October

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Shaggy Pholiota (Pholiota squarrosa)

Description: Annual that appears at first as a dense cluster of convex shaggy dark yellow caps before individually flattening out to 5-15cm across and becoming paler in colour. The shaggy appearance is retained due to its covering of red-brown upturned scales. The stem is smooth and pale above the membranous ring but shaggy similar to the cap beneath, becoming darker towards the base. Flesh is tough and pale yellow. Spores are exuded from gills that are yellow at first before turning brown with age. Rust brown spore print
Habitat: The base of many deciduous trees (willow in photo) and occasionally conifers
Season: Autumn to winter
Strategy: Parasitic causing a simultaneous white rot
Significance: Brittle fracture at point of decay, usually the base of the tree
Notes: Locally common. Not edible. Photograph taken November

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Oyster Mushroom (Pleurotus ostreatus)

Description: Annual first appearing as a cluster of grey shell-shaped caps before flattening to 4-20cm across sometimes becoming wavy and splitting at the margin. Top will become more brown and paler with age. Lateral but often absent stem. Lilac spores are exuded from white gills, becoming yellow with age

Habitat: The trunks of many broad-leafed trees, standing or fallen. Common also on stumps. Horse chestnut pictured

Season: All year

Strategy: Saprophytic causing a simultaneous white rot

Significance: Can lead to brittle fracture, especially when associated with already dead wood. Decay may be more localised on a healthy tree

Notes: Common. Edible. Photograph taken January

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Artist’s Fungus (Ganoderma applanatum)

Description: Perennial bracket ranging from 10-60cm across, found singularly and in groups. Rather flat and semicircular in shape. Very hard, concentrically ringed on top with a grey-brown cracked crust. Flesh is cinnamon brown. White pores beneath will bruise brown giving this fungus its common name, historically having been used as a tablet. Spore print brown

Habitat: The trunks of many broad-leafed trees, hornbeam pictured

Season: All year

Strategy: Parasitic causing an intensive white rot. Persisting as saprophytic after trees demise

Significance: Demise of host and/or brittle fracture of main trunk at point of decay

Notes: Locally common. Not edible. Photograph taken January

The yellow flat-footed fly (Agathomyia wankowiczii) lays its eggs inside G. applanatum causing galls on the underside of the bracket. By no means always seen, but you can be sure it is G. applanatum you are looking at if you see these galls as this is the only known case of galls on a bracket in Britain!

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Ganoderma adspersum syn. G. australe

Description: Perennial bracket ranging from 10-60cm across. Often thicker than G. applanatum but otherwise superficially very similar. Very hard, concentrically ringed on top with a red-brown cracked crust. Flesh is dark brown. Cocoa brown spores are exuded from white pores, and though they are on the underside of the bracket, spores usually end up on top of it and above it thanks to electrostaticity

Habitat: The base of trunks of many broad-leafed trees, sycamore pictured

Season: All year

Strategy: Parasitic causing an intensive white rot. Persisting as saprophytic after trees demise

Significance: Demise of host and/or brittle fracture of main trunk at point of decay

Notes: Locally common. Not edible. Photograph taken January. Difficult to distinguish from G. applanatum

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Many-zoned Polypore (Coriolus versicolor)

Description: Annual? Bracket 4-10cm across found in crowded groups, often in the hundreds. Young specimens have a velvety upper surface but this becomes smooth and leather like with age. Concentric rings of varied colours: black, green, grey, blue, brown or red. Flesh is with and tough. Spores exuded from pores leaving a straw-yellow spore print

Habitat: Dead wood, ash pictured

Season: All year

Strategy: Saprophytic

Significance: Eventual structural failure at point of decay

Notes: Very common. Not edible though does contain Polysaccharide-K an immune system boosting agent, thus used in the medical industry. Photograph taken December

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Coriolus hirsutus

Description: Annual? Bracket 4-10cm across found singly or in small groups. The top is concentrically ringed off white to brown and covered in fine grey hairs, surface greying with age. Flesh is white and tough. Spores exuded from pores leaving an off-white spore print

Habitat: Dead wood, ash pictured

Season: All year

Strategy: Saprophytic

Significance: Possible structural failure, but most often found on wood that is already lying on the ground

Notes: Locally common. Not edible. Photograph taken January

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King Alfred’s Cakes (Daldinia concentrica)

Description: Perennial rounded fruit body 2-10cm across. Usually found in groups. Brown when young but soon aging black. If cut open shiny grey to purple concentric rings can be seen. Black spores

Habitat: Most often dead ash as pictured but occasionally beech

Season: All year

Strategy: Saprophytic causing white rot

Significance: Possible structural failure. A sure sign of dead wood on ash

Notes: Common. Not edible but a good fire lighter when dry. Photograph taken January

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Coral Spot Fungus (Nectria cinnabarina)

Description: Annual? Two types: red flask shaped fruit body 1-2mm across and similar pink pustules, sexual and asexual respectively. Found in massed groups. Pink spores

Habitat: Dead wood, horse chestnut pictured

Season: All year

Strategy: Saprophytic

Significance: Eventual structural failure at point of decay

Notes: Common. Not edible. Photograph taken December

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Dutch Elm Disease (Ophiostoma novo-ulmi)

Description: Ophiostoma novo-ulmi is a microscopic ascomycete fungus, thus no fruit body is visible to the naked eye. However, tell tail signs of its presence are sudden die back in elm trees and the feeding galleries of the elm bark beetle (Scolytus scolytus) found under the bark (see photo). It is these beetles that carry the fungus’ spores from tree to tree

Habitat: Elm trees

Season: All year

Strategy: Parasitic

Significance: Demise of elm trees

Notes: Common. Not edible. Photograph taken December showing beetle galleries

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Jew’s Ear (Auricularia auricular-judae)

Description: Annual ear-shaped bracket 3-8cm across, often grouped. Jelly like when fresh but drying hard with age. Red-brown outer surface covered in tiny grey hairs often with vein like protrusions. Shiny smooth inner surface, more grey-brown in colour and often wrinkled. White spores

Habitat: Dead branches, most commonly of elder. Sycamore pictured

Season: Usually autumn but found all year

Strategy: Saprophytic

Significance: Eventual structural failure at point of decay

Notes: Very common. Edible. Photograph taken January

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Honey fungus (Armillaria mellea)

Description: Annual appearing at first as a dense cluster of convex yellow to brown caps that will individually flatten to 3-15cm across becoming depressed in the center and wavy at the rim. Dark scales often seen towards the center. 6-15cm stem swollen at the base, white to begin with but becoming brown with age, a thick white membranous ring towards the top. Flesh is white. Very pale brown spores exuded from gills that are white at first but darkening to pinkish-brown with age

Rhizomorphs or bootlaces (see photo) can be found year round under infected bark, on roots and in the soil. These are thick black thread like bundles of hyphae that can give means for the fungi to travel fairly large distances through the soil

Habitat: Roots, trunks and stumps of most tree species. Fruit bodies pictured on birch and rhizomorphs on oak

Season: Summer to early winter

Strategy: Parasitic causing an intensive white rot

Significance: Death of tree and brittle fracture at base. Considered to be one of the most dangerous parasites known to trees

Notes: Common. Edible if cooked. Photographs taken November and January respectively

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Velvet Shank (Flammulina velutipes)

Description: Annual appearing at first as a dense cluster of convex yellow caps that will individually flatten to 2-10cm, dark towards the centre and wavy at the rim. Smooth and slimy. Tough stem, 3-10cm in length yellow at top, darkening to black towards the base and darkening completely with age. Thin yellow flesh. White spores exuded from pale yellow gills

Habitat: Dead wood, trunks and branches. Commonly elm or horse chestnut as pictured.

Season: Winter

Strategy: Saprophytic

Significance: Possible structural failure at point of decay

Notes: Common. Edible. Photograph taken December. Unusually, this fruit body can withstand being frozen and thawing continuing to produce spores

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Lentinellus cochleatus

Description: Annual found in groups. Irregular funnel like cap 2-6cm across reddish-brown and darkening towards center and often split. Central stem 2-5cm similar colour to cap but darkening towards the base. White spores exuded from pale pink decurrent gills

Habitat: Old stumps

Season: Autumn

Strategy: Saprophytic

Significance: Wood decay, habitat creation

Notes: Locally common. Edible. Photograph taken December

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Clustered Bonnet (Mycena inclinata)

Description: Annual growing in dense tufts. Rounded cap expands to a bell shape of 2-3cm across, pale brown on top but darker towards the center and ribbed in appearance. 5-10cm stem that is darker towards the base, where it is covered in a fine white down of mycelium. Thin white flesh. White spores exuded from white adnate gills that darken to pink with age

Habitat: Old stumps, commonly oak

Season: Autumn

Strategy: Saprophytic

Significance: Wood decay, nutrient recycling

Notes: Locally common. Not edible. Photograph taken October

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Candle-snuff Fungus (Xylaria hypoxylon)

Description: Annual usually in groups. Upright fruit body 1-7cm tall. Fairly rounded and hairy at the bottom but flattening and branching out towards the top where it is powdered white

Habitat: Dead wood, birch pictured

Season: All year

Strategy: Saprophytic

Significance: Wood decay, nutrient recycling

Notes: Common. Not edible. Photograph taken January

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Brittle Cinder (Kretzschmaria deusta =Ustulina deusta)

Description: Annual forming a flat but wavy, grey cushion like fruit body that is white at the edges. Aging black and becoming very brittle but remaining on the tree. Black spores.

Habitat: The base or roots of many deciduous trees. Ash pictured

Season: Spring to summer

Strategy: Parasitic causing simultaneous white rot

Significance: Likely brittle fracture at base or roots

Notes: Common. Not edible. Photograph taken January. “This is a particularly dangerous decay fungus” – David Lonsdale ‘Principles of Tree Hazard Assessment and Management’ 1999. There are usually no warning signs and can be very difficult to detect

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Hoof Fungus (Fomes fomentarius)

Description: Perennial bracket ranging from 5-50cm across. Hoof like in appearance with its horn like crust and concentric grey zones. Hard and woody to touch. The flesh is hard, fibrous and cinnamon brown. Found as either a single fruit body or with several on the same stem. Lemon-yellow spores exuded from grey-brown pores

Habitat: The stems of birch, beech and sycamore. Beech pictured

Season: All year, sporulating early summer

Strategy: Parasitic causing simultaneous white rot

Significance: Possible fracture at point of decay

Notes: Uncommon. Not edible. Can be used for tinder. Photograph taken February

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What’s growing on that tree? This is a question you may have asked yourself once or twice on a walk around your neighborhood, in the park, or out in the wilderness somewhere. If you’ve ever wondered about an odd-looking growth on a trunk, stump, or branch, you’re not alone. Many of us would love to be masters at identifying tree fungus, so that’s why we’ve made this handy guide!

Keep in mind that fungus growing on a tree is usually a good sign that the tree is decaying or dying. Because fungi feed on organic matter, they are often a sure sign that a tree is nearing the end of its life. Tree fungi come in diverse arrays of shapes and sizes. There are a few growth forms of fungus that are easily identifiable. We’ll go over some of the main types of tree fungus and how to identify them.

In order to identify a tree fungus, the main thing to look for is the general shape and texture. The part you see is actually the fruiting body of a fungus, and it’s just the tip of the iceberg. The rest of the organism is the hidden mycelium which the fungus uses to retrieve nutrients, like the roots of a plant. The most important part of a fungus in order to identify it, however, is the visible part. Here are 3 common types of tree fungus and examples to look for:

1. Shelf Fungus

This type of fungus is named after the easily identifiable shape they create. They look like little shelves that protrude from the trunk or branches of a tree. Although they all exhibit the same general shape, they can be all sorts of colors and textures.

Artist’s Conk (Ganoderma applanatum)

Another super abundant shelf fungus is the artist’s conk. You can find it growing on many species of trees, from conifers to broad-leaf trees. It’s a thick shelf fungus, with brown on the top and white on the bottom. If you think you’ve identified one, to be sure, try drawing a picture on the underside with a twig or even your fingernail, and see how the artist’s conk got its name!

Turkey Tail Fungus (Trametes versicolor)

One of the more common species of shelf fungus is the turkey tail fungus. This one can be found all over the world, and the psychedelic colors it displays make it easy to identify.

2. Cap Fungus

When one thinks of a mushroom, the first image to appear in their head is the shape of a classic cap mushroom. Although this type of fungus is more common growing on the ground than on a tree, it’s still possible to see them on a tree trunk.

Oyster Mushroom (Pleurotus ostreatus)

An incredibly common cap fungus is the oyster mushroom. These are eaten worldwide, and are the target of many a mushroom forager. They grow in clusters and are a creamy white color. Oyster mushrooms can be found nearly everywhere in the temperate regions of the world, growing on the trunks of broad-leaf trees.

Fly Amanita (Amanita muscaria)

Fly amanita mushrooms, also simply called amanita mushrooms, can be found anywhere. You may wonder why a mushroom that grows out of the ground is on our list of tree fungus. Well, it’s because it is a tree fungus! This one is associated with the roots of a tree, an incredibly common life strategy many fungi have. Amanita mushrooms are beneficial for their host, by reducing the number of parasitic fungi that would otherwise grow on the tree. Their easily identifiable, too. Look for the bright red cap with white spots.

3. Jelly Fungus

Another fungus name that describes the organism all too well is the jelly fungus. These gelatinous blobs are sometimes called snot fungus due to their gooey, amorphous forms. It’s relatively easy to recognize this type of fungus. Here’s my favorite example of jelly fungi:

Wood Ear (Auricularia auricula-judae)

Wood ear fungus is coppery red and resembles a shelf fungus in its shape. Due to its gelatinous form, it’s actually a type of jelly fungus. You’ll find this one on dead or dying branches of trees, usually in the colder months of the year. It can also be on fallen wood on the forest floor. Like oyster mushrooms, wood ear fungus is a delicacy in some countries, despite the weird texture!

Remember – don’t go around eating random mushrooms! Many are poisonous, hallucinogenic, or deadly, and it’s easy to mistakenly identify different types. Go with a seasoned mushroom forager who knows what they’re doing. If you’re curious about learning more about foraging for mushrooms, check out our guide on identifying edible mushrooms.

An arboreal murder mystery: What is killing beech trees?

By Gabriel Popkin July 28, 2018

Ohio biologist John Pogacnik admits to mixed feelings about having discovered the latest disease imperiling a major American tree.

Pogacnik first noticed American beech trees with striped and shriveled leaves in 2012 during a routine survey of forests owned by his employer, Lake Metroparks. He didn’t think much of it at first: Just a few trees looked sick, and it had been a strange year, with an unusually warm winter and dry spring.

By the next summer, Pogacnik was seeing ailing trees throughout the six-county region in northeast Ohio where his agency manages more than 35 parks. He alerted colleagues at the Ohio Division of Forestry and the U.S. Forest Service.

“I’m glad to have found it, to just put it out there and let people know,” he said. “But it’s still not the greatest feeling in the world.”

Beech leaf disease has now popped up in nine Ohio counties, two other states and Canada, and its spread shows no sign of slowing. The disease has already felled young saplings; mature trees, some hundreds of years old, appear to be on the brink of death. Scientists fear the beech could soon face a plague as serious as those that have devastated chestnut, elm, hemlock and ash trees. “It has all the signs of a significant, emerging pathogen,” said Constance Hausman, a biologist at Cleveland Metroparks.

Scientists are gearing up to fight back, but they face a major challenge: Nobody knows what beech leaf disease is. Searches for a virus, bacteria or fungus — all common tree pathogens — have come up empty. Researchers are facing an arboreal murder mystery.

“At this point I’m not sure anyone is able to rule anything out definitively,” said James Jacobs, a plant pathologist with the Forest Service in Saint Paul, Minn.

The American beech ranges from the Gulf of Mexico to southern Canada, and from the Atlantic Ocean to eastern Texas and Wisconsin. Nature lovers have long admired the tree’s massive trunks and lush, light-green foliage, which turns electric-yellow in the fall. Beech’s smooth gray bark makes an irresistible canvas for carving initials into hearts, many of which long outlast the romances they memorialize.

Though largely shunned by the timber industry, beech is among the most ecologically important trees in the eastern United States. In the north, where oaks are rare, bears, deer and other animals depend on beech nuts for survival. Beech’s almost unmatched ability to grow in deep shade — and the fact that deer don’t prefer its leaves — has made it among the most common trees in the older forests of many eastern states and the District, where it dominates the understory of Rock Creek Park. A beech dieback “would be a huge loss,” Hausman said.

Despite its abundance, the beech has its challenges. For almost a century, a fungal infection carried by an insect has attacked American beech bark and killed many large trees.

The new and mysterious disease is apparently unrelated to the older malady. Infected leaves blacken between their nutrient-carrying veins, then shrivel like bits of paper tossed in a fire. No infected tree has ever been known to recover, Hausman said, though it’s not clear exactly how, or how fast, the disease kills trees.

Scientists and funding agencies, already overwhelmed by tree-killers such as emerald ash borer, responded hesitantly to early reports of the disease.

“To be honest, I initially tried to stay out of it” when Pogacnik first called him, said Enrico Bonello, a plant pathologist at Ohio State University in Columbus. “I said, ‘Let’s wait and see what happens.’ Sometimes you observe things in nature that are very ephemeral; they go away.”

Beech leaf disease didn’t go away. Instead, it spread from Pogacnik’s Ground Zero to nine Ohio counties and parts of New York and Pennsylvania. Hoping to identify a cause, researchers began grinding up leaves from infected and uninfected beech leaves and using a technique that amplifies pieces of DNA unique to fungi, bacteria and viruses, to see whether diseased trees harbor organisms that healthy ones don’t. The studies came up empty.

Bonello and a graduate student are now enhancing the tests using a newer method called next-generation sequencing, which could turn up organisms that the earlier studies missed. “You’re essentially trying to find a needle in a haystack by comparing two haystacks,” he said, “one with a needle, one without.”

If diseased leaves yield DNA not present in healthy ones, the researchers will have a suspect, though they will still need to isolate it and prove that it can infect healthy trees. Bonello expects to have initial results within a year.

The study may turn out to be moot, however, thanks to a possible culprit revealed at a May meeting in Parma, Ohio. Ohio Department of Agriculture plant pathologist David McCann reported that he had found thousands of microscopic worms called nematodes wriggling on infected beech leaves. McCann sent specimens to USDA nematologist Lynn Carta in Beltsville, Md., who discovered that they were related to a bush-dwelling nematode known in New Zealand but never seen in the Americas. Research is now underway to determine whether it is the same species recently found on beech trees in Japan.

McCann doubts that his nematodes will prove to be beech leaf disease’s sole cause. Feeding by those worms tends to create discolored or dead spots on leaves, not the linear bands seen in beech leaf disease.

Others are more optimistic. “Right now it’s probably our best lead,” said Jennifer Koch, a Forest Service biologist based in Delaware, Ohio, who has coordinated much of the research that has been done.

After six years of working on the cheap, beech leaf disease researchers just got some welcome news. In June, the Forest Service released its first dedicated funding — $156,000 — to help track the disease’s spread and accelerate the search for a cause. Hausman is leading the tracking effort; she has helped develop a free smartphone app that will allow foresters and others to quickly enter information about beeches’ locations and conditions.

Koch and scientists at the Holden Arboretum in Kirtland, Ohio, will use part of the funding to infect healthy beeches with McCann’s nematodes and see whether they get sick. If they do, it will be the first break in a six-year-old cold case. The research funding “really changes the landscape in terms of being able to move forward and hopefully find what the problem is,” said David Burke, a biologist at the arboretum.

There’s also the question about how to respond to a mystery pathogen. That decision falls largely to the USDA’s Animal and Plant Health Inspection Service, which can impose quarantines and take other measures to keep pests and disease from spreading. APHIS scientists have participated in some of the research, but a spokeswoman wrote in an email that the agency is not taking other action on the disease.

Faith Campbell, vice president of the nonprofit Center for Invasive Species Prevention in Fairfax, Va., fears that regulators are missing an opportunity to try to limit the damage by restricting the movement of beech trees out of diseased areas. She’s especially concerned that the landscaping industry could inadvertently spread the disease; already, a shipment of infected beech trees from Ohio has shown up at a nursery in Ontario.

“I don’t think we should wait around to see” whether the disease gets worse, Campbell said. “The longer you wait, the more difficult it’s going to be to control.”

D.C. says its tree canopy is growing. Federal researchers disagree.

Trees know when deer are eating them — and how to fight back

This disease has killed a million trees in California, and scientists say it’s basically unstoppable

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