Identify tree fungi: 16 fungi on trees

If fruiting bodies of fungi form on the trunk or at the base, then the tree is sick. In order to recognize how bad such an infestation can turn out, it is helpful to be able to identify the individual tree fungi.

Leaf and needle mushrooms

There are many types of tree fungi. In order to be able to determine these, it must be recognized where they are located. There are, for example, tree fungi that settle on leaves and needles:

Pine chute (Lophodermium seditiosum)

• massive dropping of the needles
• first turn yellow to brown-red
• Pines and conifers affected
• Fungus overwinters in spore beds
• are on discarded needles
• from there spread in spring
• from the bottom up
• bearings open when damp
• Spores are shot out
• Open and dispose of all discarded needles

Note: Infested old wood from a distant branch or a felled tree can still be used as wood for the fireplace or a campfire or a fire bowl.

Rust mushrooms (Pucciniales)

• Upper side of the leaves small pustules
• yellow or red
• Underside of spore bearing
• Leaves die off over time
• leaf shedding before autumn
• usually does not end fatally
• however, it can weaken the tree
• often new leaf formation as early as summer
• very often as apple grate and pear grate
• often also reduces the quality of the harvest

Molds (Aspergillus)

• many different types of mold
• can be confused with powdery mildew
• white coating on leaves
• often after very humid, long periods of rain
• not harmful to plant
• not to be compared with the food mold
• Only remove for aesthetic reasons
• often found under the trees

Note: The mold found outdoors cannot be compared to the mold found on indoor plants. You always have to intervene here so that it does not shift to the walls of your apartment and spread here.

Powdery mildew species

• often seen on fruit trees
• Apple powdery mildew
• American gooseberry powdery mildew
• attack leaves and all green parts
• Wipeable coating on the upper side of the leaves
• first white then dirty brown or gray
• Leaves dry up
• Only plant trees that have been grown to be resistant to powdery mildew
• Fight with fresh, untreated cow's milk
• available in health food stores or from farmers

Wood-destroying tree fungi

The wood-destroying fungi, which usually sit on the trunk or on the thick branches of a tree, are usually very dangerous for the tree and usually cannot be combated adequately. Here they feed on wood:

Bleeding layer mushroom (Stereum sanguinolentum)

• great expansion on the trunk
• mainly on conifers
• often also on dead wood
• Cones protrude horizontally from the trunk
• if injured, the fungus immediately turns blood red
• inconspicuous smell and taste
• does not belong to the edible mushrooms
• Wood parasite

Brown rot (destructive rot)

• actually known from tomato plants
• is caused by various wood-decomposing fungi
• penetrate the wood and break down the cellulose
• Cell walls dry out
• the wood becomes brittle
• Grind the infected wood between your fingers
• only powder left
• often with robinia, pine, oak and birch

Tip: A tree that is dead but still stable after a fungal attack does not necessarily have to be removed. Depending on its location in the garden, it is still very suitable as Support for climbing plants.

Burn crust mushroom (Kretzschmaria deusta)

• very much feared
• black, charcoal-like fruiting bodies
• sit on the bark
• Fungal rot in its early stages is easy to miss
• Main fruit with pillow-like collective fruiting bodies
• Infestation occurs through injuries in the trunk
• causes white rot that extends far into the trunk
• Creates strong road safety
• linden, horse chestnut and red beech are particularly affected
• determination only possible through the microscope

Note: If a fruit tree has to be felled because of a fungal attack, this does not require a permit. For all other trees, you should obtain a felling permit from the responsible authority, which in such a case will be issued without any problems.

Common mosaic layer mushroom (Xylobolus frustulatus)

• many different earth colors
• large area
• like a spring-loaded puzzle
• hence the name mosaic layer mushroom
• corky tough meat
• Caution inedible
• causes harmful white-hole rot
• Tree inevitably dies
• also occurring on dead wood
• destroys substance Wood is unsuitable for further processing

Pine fire sponge (Phellinus pini)

• from the family of the fire sponges
• many species known
• Also on fruit trees mostly apples
• dark brown fruiting body
• green color due to algae
• Caution inedible
• very hard meat
• pleasant smell
• attacks all conifers, mainly pine

Lackporling (Ganoderma)

• different types
• Shiny Lackporling also known as medicinal mushroom
• very harmful to trees
• spreads through injuries in the cortex
• mostly from the bottom up
• spreading very slowly
• can be present in the trunk for decades
• without symptoms
• in the final phase the tree can fall over
• grow flat horizontally in a semicircular shape from the trunk

Note: The fruiting body hanging on the outside of the trunk is not the problem, but the mycelium growing inwards, the fungal network. Therefore, it is not enough to remove the fungi on the outside to save the tree.

White rot (corrosion rot)

• also caused by a fungal attack
• different fungi can be the cause
• for example the Lackporling
• Whitening of the wood
• Fiberization
• Loss of stability
• Fungi break down lignin, hemicellulose and cellulose in wood

Tip: If a fruit tree has been attacked by a fungus and there is no risk to its stability, then this tree can bear fruit for years and does not have to be felled immediately.

Tinder fungus (Fomes fomentarius)

• forms tube layers on the trunk
• Rust to orange brown in color
• hard top
• plate-shaped or hemispherical
• hard meat
• Caution inedible
• predominantly on deciduous trees
• is easily confused with other sponges or lacquer pores
• Medicinal mushroom in Chinese medicine

Note: The tinder sponge was used in earlier times to make clothing such as hats. Today it is still partly used to dye clothes.

Mushrooms on shoots

Often there is also a fungal attack on the young shoots of a tree. If this is the case, it is particularly important to determine because the wood as a whole can still be saved by removing all infected shoots:

False white stem cup (Hymenoscyphus fraxineus)

• mainly on ash shoots
• rediscovered only in 2008
• the white stem cup is not dangerous
• but the doppelganger named here does
• Pathogen causing ash dieback
• probably brought in via Poland
• Caution inedible
• identified as small white to yellow tree fungi
• with a domed hat
• mainly sitting on twigs and branches

Pine shoot death (Sphaeropsis sapinea)

• yellow to red-brown discolouration on needles
• Shoots die off
• round, small black fruiting bodies
• hardly recognizable
• turn dirty yellow to orange when wet
• frequent occurrence in wet spring and hot summer
• Damage often confused with road salt damage
• Pine trees die within a few months of being infected
• Water enough to prevent fungal attack
• remove and dispose of infected shoots

Root fungi

Finally, attention must also be drawn to the various soil fungi that multiply on the roots of trees settle, feed on it and thus destroy a tree from below if the infestation is not recognized in time will:

Honey fungus species (Armillaria)

• 30 different types
• often in autumn at the foot of the tree
• mostly in small groups
• up to 20 centimeters high thin mushrooms
• large forest pest
• the trees usually die
• very harmful honey yellow honey fungus (Armillaria mellea)
• as well as the dark honey fungus (Armillaria ostoyae)
• both able to decompose wood
• both conifers and deciduous trees

Tip: You can define a honey fungus as dangerous if it grows out of the ground further away from the tree. Then the fungus has attacked the roots running underground.

Root sponges (heterobasidion)

• Common root sponge (Heterobasidion annosum)
• Pine root ridge
• also known as red rot
• Caution inedible
• sour odor
• irregularly shaped humped fruiting body
• white to yellow color
• causes root rot
• can cause millions in damage to forestry

Tip: If a tree had to be felled due to a fungal attack, the stump can remain in place for many years for decorative reasons, for example with a flower pot. Because this also offers a natural habitat for many microorganisms.

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