What Is The Fungus That Grows On Trees

You should know the risk your gardening tree or plants may suffer that why today we answer the question What is the fungus that grows on trees.

Fungi are present in any garden and given their characteristics they can go through different phases while waiting for their opportunity, that is, the right conditions to attack plants.

Most fungi that affect plants are microscopic but are sometimes able to form more visible structures. Especially when we talk about trees.

More than 100,000 types of fungi are known, of which around 50 cause diseases in man, the same number in animals, and more than 15,000 species of fungi damage plants.

Every plant in the garden is attacked by some type of fungus, and some parasitic fungi can attack different types of plants.

As for the trees I am going to describe some of the most common fungi and how to treat it.

Common Large Fungi :

You will be surprised how many fungi are out there, and the importance of taking care of your plants. 

Chicken of the woods

One can easily spot the chicken of the woods mushroom by its impressive size and vibrant yellow-orange colors. 

This large polypore has surprised many a nature lover the first time they found it! Yet did you know they’re also edible, and considered a delicacy in some parts of the world?

This mushroom has a lemony, meaty taste. Some think it tastes like its chicken namesake; others describe the flavor as being more like crab or lobster.

Whatever your opinion, the chicken fungus makes a great substitute for meat in almost any dish.

It’s important to note that this is one of those mushrooms that sometimes causes gastric distress in certain people. 

If you want to avoid a possible stomach misadventure, only try a little bit your first time to see what it does to you. 

Also always avoid chicken of the woods growing on conifers, eucalyptus, or cedar trees, as these are reported to contain toxins that can make people sick.

Birch polypore 

Fomitopsis betulina (previously Piptoporus betulinus) is commonly found in countries around the world that have birch forests. 

This edible and medicial polypore has been extensively studied and there is ample evidence supporting the antibacterial, anti-parasitic, antiviral, anti-inflammatory, anticancer, neuroprotective, and immunomodulating activities. 

Birch polpores are a common basidiomycota brown rot macrofungus that grows on decaying birch trees.

By the time the white fruiting body emerges, decay to the tree is extensive. 

In 1753 Carl Linnaeus first described this fungus and referred to it as Boletus suberosus, and later the French mycologist Jean Baptiste Francois (Pierre) Bulliard changed the specific epithet to betulinus – a reference to the birch trees (Betula spp.). 

In 1821, Bulliard transferred this very common and widespread polypore to the genus Polyporus, where it remained for sixty years.

In 1881, Finnish mycologist Petter Adolf Karsten transferred the birch polypore to a new genus, Piptoporus, which he had created.

Birch polypores have white-to-brownish fruiting bodies. They are annual, emerging from the bark of dead or dying birches in spring and summer. 

They deteriorate slowly and persist through the winter; although when they are brown or blackened they are no longer useful. Most fungal conks are woody and hard, but birch polypores have a soft, leathery feel and an inflated look. 

They are attached to the tree by short, fat stalks. The smooth upper surface folds over at the outside edges, leaving a rounded rim around the flattened lower surface. 

They start as a subglobose then forming a ‘hoof’ shape finally becoming an enlarged flat bracket.


On average these polypores reach 6cm (3”) high and 30cm (12”) wide.


Birch polpores are almost exclusively restricted to dead or dying birch trees. The brackets are annual but may persist through one winter. They can be found throughout northern Europe, Canada, Asia, and in several states throughout the U.S.

Spore Print



Although these bracket fungi persisting throughout the year, they are annuals and release spores in late summer and autumn.


This is a polypore so there are no gills. They have small white tubes that are packed together at a density of 3 or 4 per mm; they measure between 1.5 and 5mm deep and terminate in white pores that brown as they age.


Birch polypores are not known as being culinary fungi however it can be used in a variety of ways. Young polypores can be sliced thin, marinated then roasted. 

Cut up and dried, they can be used as a tea although it isn’t that great tasting. 

Dehydrating is a great way to preserve them long term (although exactly how long is not known). Once dehydrated they can be powdered, then add to any dish you prepare. Store in a cool, dark location once dehydrated.

Other Name

Birch Bracket.

Honey fungus

Honey fungus is the common name of several species of fungi within the genus Armillaria

Honey fungus spreads underground, attacking and killing the roots of perennial plants and then decaying the dead wood. It is the most destructive fungal disease in UK gardens.

Honey fungus can attack many woody and herbaceous perennials. 

No plants are completely immune, but some have very good resistance, such as Juglans nigra (black walnut) and Acer negundo (box elder).

Symptoms you may see:

  • Upperparts of the plant die. Sometimes suddenly during periods of hot dry weather, indicating failure of the root system; sometimes more gradually with branches dying back over several years
  • Smaller, paler-than-average leaves
  • Failure to flower or unusually heavy flowering followed by an unusually heavy crop of fruit (usually just before the death of the plant)
  • Premature autumn color
  • Cracking and bleeding of the bark at the base of the stem
  • If suitable conditions permit, mushrooms are produced in autumn from infected plant material
  • Dead and decaying roots, with sheets of white fungus material (mycelium) between bark and wood, smelling strongly of mushrooms. This can often be detected at the collar region at ground level, and rarely spreads up the trunk under the bark for about 1m (3¼ft). This is the most characteristic symptom to confirm diagnosis
  • Rhizomorphs (see images 2, 3 and 4 above) are often difficult to detect, especially for the most pathogenic species, and they are particularly difficult to find in the soil

The most common species in gardens are A. mellea and A. gallica. There is a rarer occurrence of A. ostoyae. The remaining species A. cepistipes, A. tabescensA. borealis and A. ectypa have not been found in gardens according to a survey done by RHS scientists. A. mellea and A. ostoyae are the most damaging species. A. gallica is considered to be less damaging although more research is needed to find out how destructive these species are.

The fungus spreads underground by direct contact between the roots of infected and healthy plants and also by means of black, root-like structures called rhizomorphs (often known to gardeners as ‘bootlaces’), which can spread from infected roots through soil, usually in the top 15cm (6in) but as deep as at least 45cm (18in), at up to 1m (3¼ft) per year. 

It is this ability to spread long distances through soil that makes honey fungus such a destructive pathogen, often attacking plants up to 30m (100ft) away from the source of infection.

Crown rot 

Crown rot, sometimes called southern blight or southern stem rot, is caused by several soil-borne fungi. 

It affects herbaceous plants and some woody plants but is most commonly found on ajuga, anemone, campanula, chrysanthemum, delphinium, hosta, hydrangea, iris, narcissus, phlox, rudbeckia, scabiosa, sedum, and tulip.

The problem generally requires removal of the diseased plant.

Symptoms and Diagnosis

Crown rot causes deterioration and rotting of the tissues at the crown of the plant causing the leaves to turn yellow, collapse, and die. 

When the temperature exceeds 70 degrees F, infected plants develop discolored, water-soaked stem lesions near the soil line. 

During periods of high humidity, coarse cottony webbing (mycelium) develops and fans out over the stem base and surrounding soil. 

Sclerotia, which resemble mustard seeds and vary from white to reddish tan to light brown in color, develop at the base of the plant. Enough sclerotia may form to create a crust on the soil.

Life Cycle

The fungi which cause crown rot (Pellicularia rolfsii, Sclerotium delphinii, and Sclerotium rolfsii) survive in the soil and are spread by flowing water, transported or contaminated soil, transplants, and tools. 

Conditions of 86–95 degrees F for several days with intermittent rains are conducive for fungal development.

Verticillium wilt

Verticillium wilt is a serious fungal disease that causes injury or death to many plants, including trees, shrubs, ground covers, vines, fruits and vegetables, and herbaceous ornamentals.

It is a disease of the xylem, or water-conducting tissues, in the plant. Commonly infected woody plants include maple, smoke-tree, catalpa, and magnolia, among others.



Verticillium wilt is caused by a soil fungus called Verticillium dahliae. Another species, Verticillium albo-atrium, is less common. 

This fungus lives in soil as small, darkened structures called microsclerotia. These microsclerotia may lie dormant in the soil for years. 

When the roots of susceptible plants grow close to the microsclerotia, the fungus germinates and infects the roots of the plants through wounds or natural openings. 

The fungus spreads into the branches through the plant’s vascular system and simultaneously causes the plant cells to “plug” themselves. 

Once the xylem is infected, it becomes so plugged that water can no longer reach the leaves. Verticillium can also be spread to plants through wounds on branches or trunks.



One or more branches, usually on one side of the tree, wilt suddenly. Sometimes the leaves turn yellow before they wilt, or leaf margins turn brown and appear scorched. 

In some instances, there is a slower decline in new twig growth, or dead twigs and branches appear. 

On maples and tulip trees, elongated dead areas of bark, called cankers, may appear on diseased branches or trunks. 

In Illinois, these symptoms usually occur in July but can be seen as early as May or as late as October.

Internally, diseased trees may exhibit discolored sapwood in the recent annual rings. 

In maples, Verticillium produces greenish streaks; in smoke-tree, the streaking is yellow-green. In other woody plants, the discoloration is brown. 

In some trees and on younger twigs, discoloration does not occur or is found several feet below the point where leaves are actually wilting. This makes identification difficult.


There seem to be two forms of the disease, one in which plants die slowly over several years and another where they die rapidly within a few weeks. 

Trees that show minor branch wilt one year may show more the next year or may not show symptoms again for several years. There is some evidence that unbalanced fertilization (too much or too little nitrogen, for example) exacerbates this disease.


The appearance of streaking helps to identify the disease but does not guarantee that the tree has Verticillium. Sometimes other factors or diseases cause discoloration of sapwood. 

Only laboratory examination can positively diagnose the disease.

For laboratory identification, select twigs that are about 1/2-inch in diameter and approximately eight inches long. 

The twig must be from a branch that is actively wilting, but not yet dead. 

Wrap the samples in wax paper or other material that will keep the sample from drying out. 

Mail the sample (overnight, if possible) with your name, address, and a history of the problem to the University of Illinois Plant Clinic. Phone 217-333-0519

There is a charge per sample. 

Black spot

Black spot is a fungus that primarily affects roses but can also be found on other ornamental and garden plants. 

It can be found on flowers, fruits, and leaves and is problematic when the weather is hot and humid. 

Problems are greatest when leaves stay wet for 6 hours or more. 

Black spot produces round, black spots with fringed margins that can be up to 1/2 inch in diameter. 

The spots form on the upper sides of leaves. The leave tissue surrounding the spots turns yellow. 

Usually lower leaves are infected first, and infected leaves often fall off the plant early. 

Black spot overwinters in fallen leaves and branches. Water splashing on the soil under plants catapults the spores unto the plants above.

Powdery mildew

There are many different species of the fungal disease powdery mildew, and each species attacks a range of different plants. 

Unlike many other fungal diseases, powdery mildew thrives in warm, dry climates, though it does require fairly high relative humidity (i.e., humidity around the plant) to spread. 

In cooler, rainy areas, it does not spread as well. That being said, it is capable of infecting your plants under a wide variety of conditions.

When the fungus begins to take over one of your plants, the mildew that forms is made up of many spores. 

These spores carry the infection to other plants through the wind. Powdery mildew can slow down the growth of your plant. 

In some cases, if the infection is severe enough, powdery mildew can kill your plants. 

How to identify powdery mildew damage:

  • Plants infected with powdery mildew look as if they have been dusted with flour.
  • Powdery mildew usually starts off as circular, powdery white spots, which can appear on leaves, stems, and sometimes fruit.
  • Powdery mildew usually covers the upper part of the leaves, but may grow on the undersides as well.
  • Young foliage is most susceptible to damage. Leaves turn yellow and dry out.
  • The fungus might cause some leaves to twist, break, or become disfigured.
  • The white spots of powdery mildew will spread to cover most of the leaves or affected areas.
  • The leaves, buds, and growing tips will become disfigured as well. These symptoms usually appear late in the growing season. 

Lichens On Trees

There are at least 13,000 species of lichens living throughout the world. 

Lichen species are so numerous and diverse that there are individual exceptions to most general statements about them. 

Scientific knowledge about lichens has expanded significantly during the past few decades, and new discoveries continue. 

Most lichen species grow best where there is sufficient light and moisture within a moderate temperature zone. 

However, some lichen species are very adaptable and hardy.

When left undisturbed, lichens live in many varying climates and altitudes throughout the world. 

Some species can survive the most unfavorable climatic extremes of arctic, alpine and desert regions by reducing metabolic activity for extended periods of time. 

Yet individual species may only exist within a restricted habitat or geographic range. 

Most lichens are very sensitive to air pollution, and like canaries in coal mines, they may serve as indicators of air quality.

Lichens are often found on tree trunks, branches, and twigs as the bark provides a stable place to reside to collect needed sunlight, rainwater, and materials from the air. 

They grow on healthy trees, as well as stressed or otherwise unhealthy ones. 

The appearance of colorful organisms growing on the bark of trees or shrubs in the landscape sometimes causes concern for the homeowner. 

Homeowners may find lichens mysterious and incorrectly associate them as the cause of plant diseases or misidentify them as a type of moss.

Many lichens are more evident on stressed or old tree trunks and branches giving the appearance of a “cause and effect” association with disease and decay. 

The primary reason for their more likely presence on those trees and branches with reduced or partial foliation is the resulting increase in available sunlight. 

The bark of a healthy tree continues to expand and slough off with the growth of the tree. 

The bark of an older or stressed tree may become more brittle with more cracks and uneven surfaces permitting lichens to attach themselves more readily. 

As bark ages, it changes in chemistry, texture, and ability to retain water, thereby influencing the type of lichen capable of living there.

While fungi-within-a-lichen associations do not harm trees, some fungi outside of a lichen relationship can and do penetrate damaged or dead wood tissue and commence the decomposition of the tree. 

Fungi are one of the few living organisms that can break down all of the substances in wood tissue and are essential in nature in clearing away fallen tree trunks and in depositing the remaining material into the ground in the forest. 

A diseased or stressed tree can have both lichen and separate fungal organisms growing on the same dead branch or portion of the tree. 

In that case, the homeowner or tree expert may need to prune away the dead tissue for the benefit of the remaining plant. 

In making these types of decisions, homeowners need to understand the unique nature of lichen and the differences between those fungi within a lichen symbiotic relationship and other fungi operating separately.

Tree fungus treatment

Fungicides are substances that act as a poison for fungi, whose Latin name is fungi, from where the name comes. 

The fungicides that exist can be very varied, although, broadly speaking, they can be divided into natural fungicides and chemical fungicides.

In the case of natural fungicides we will be talking about substances produced by nature and which act as a poison for fungi, which eliminate them without leaving traces of artificial substances in the environment. 

On the contrary, in the case of chemical fungicides, we will be talking about artificial substances that act in the same way when it comes to eliminating fungi, but that, unlike natural fungicides, do involve the release of toxic substances in the environment.

In fact, one of the problems that arise when treating fungi in plants such as fruit trees is that they are plants destined to be consumed as food. 

In this way, if chemical fungicides are used, these toxic substances will pass to the body that feeds on them, whether they are people or animals since food contamination occurs. 

In this way, and especially in the case of plants such as fruit trees, it is much better to opt for homemade and natural fungicides, which will allow us to eliminate the fungi of the fruit without jeopardizing the health of the future diners.

Homemade fungicides to treat fruit trees

These are the best natural fungicides to treat fungus on fruit trees, as well as a very effective technique to eliminate these parasites naturally and ecologically.


One of the easiest homemade fungicides to make is the one that can be made from cinnamon. 

Cinnamon is obtained from the bark of the tree known as cinnamon.

In addition to being an excellent condiment in the kitchen, this substance has fungicidal properties that will prevent fungi from spreading through our plants.

To use it, it is best to dissolve a generous amount of cinnamon in a liter of water, let it sit for at least one night, and then spray that water on the affected areas of the fruit tree. 

Another way to apply it is by covering the soil around the tree with a good amount of cinnamon, which will be especially useful in case the fungi are affecting the roots.

Sodium bicarbonate

Another of the most powerful natural fungicides that we can manufacture at home is the one made from sodium bicarbonate. 

To prepare it, we must mix a tablespoon of baking soda with one of natural soap, and add a liter of water. 

Once the mixture is well dissolved, it can be applied to the leaves of the tree with a sprayer. In this recipe, baking soda is the part that acts as a fungicide. 

However, it is necessary to add a spoon of natural soap to it so that the formula adheres better to the leaves.

Discover here more Uses of baking soda in the garden and orchard.

Apple vinegar

Another natural product that has fungicidal properties is apple cider vinegar. 

To prepare the homemade fungicide from apple cider vinegar, it is recommended to mix the vinegar with water in a ratio of 50/50 and add a teaspoon of natural neutral soap. 

Once the mixture is well dissolved, it can be applied directly to the fruit tree with a spray.

Absence of water

One of the factors that we have to take into account when eliminating fungi is that these types of organisms always proliferate in humid areas or with excess water.

In this way, if the fruit trees, or any other type of plant, have fungi, it is possible that it is due to an excess of water in the irrigation. 

Therefore, a good idea to eliminate fungi is to reduce excess water in the environment.

However, this measure does not usually completely destroy the fungal spores, but will simply slow their growth. 

However, it is a good way to enhance the effects of the fungicides mentioned above, so a combination of less water and a natural fungicide will be perfect to eliminate the presence of fungi in any type of tree.

Keep these tips in mind when using fungicides:

  • A fungal disease in plants can be misdiagnosed easily. Check with your local county extension office for help identifying plant disease. They may also be able to recommend a treatment strategy for your lawn or garden.
  • Often, plant diseases are transmitted when leaves are wet. Ground level watering and good air circulation can be used to keep leaves dry.
  • Many fungicides remain on the surface of plant tissues and do not spread throughout the plant. Others penetrate the cuticle and circulate through plant tissues.
  • Pruning shears and other tools can carry plant diseases from one plant to another. Learn about garden sanitation to prevent spreading fungal pathogens yourself.
  • Although they can slow or stop the development of new symptoms, many fungicides are designed only to prevent disease. These are not highly effective after symptoms have developed.

Is tree fungus poisonous

If your read the article you know some may be others not. But here I leave your with 3 dangerous tree fungi you should watch out for


A semicircular, firm, pitted upper, stalkless growth on lower area of tree, brown or grey -‘Bracket’ fungi, is most likely a Ganoderma of some kind. Ganoderma bracket fungi are poisonous and compromise the structural stability of trees.

2.King Alfred’s Cakes

Black ‘balls’ appearing on (or spreading to live wood from) dead branches, firm, dense, occasionally in clumps are Daldinia Concentirica (King Alfred’s Cakes!). Daldinia Concentirica is poisonous and compromises the structural integrity of the upper parts of the tree.

3.Ustulina Deusta

A black tar-like carpet of pitted bumps and lumps with some white patches around the base of tree or on dead stumps, this is likely to be Ustulina Deusta. This dangerous fungus can cover areas up to a meter long, often found in an open wound on a tree, in a crack or crevice in deeper fissures near the base of the tree. Ustulina Deusta is another poisonous fungus that will compromise the structure of a tree.

If you see any of these fungi, it is important to contact a professional tree surgeon to deal with the problem so that trees will not damage property should their structure become unsound because of the fungi.

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