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| Tree
illnesses / diseases and tree pests |
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| The
important symptoms and characteristics of individual trees can
be found in the index of deciduous trees. |
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| Apart
from illnesses that affect the leaves, trees can also be affected
by pests and other damages. |
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| Abiotic
damage |
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| Hail,
high winds, frost, dry spells, etc. can damage a tree. The appearance
of these damages can be numerous (dried leaves, cracked bark,
broken limbs). Parasites can attack the host plant in these
damaged areas. |
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| Ants |
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| If
ants are prevalent at the base of the trunk and if there is
saw dust coming from the trunk, then this indicates damage to
the tree. Ant colonies can be expected in the trunk as they
search for a cavity or tree rot for a new home. The tree should
be watched carefully because the foothold could be in danger. |
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| Aphides |
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| Aphides
affect almost all trees. They deplete the leaves of nutrients
and pollute them with their excretion, known as honeydew. Over
800 species exist throughout central Europe. Normally, aphides
are not harmful for the tree. |
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| Frost
cracks |
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Frost
cracks form because of high temperature fluctuations from
the trunk center to the outside. The tree forms frost strips
caused by the overlapping of bark (see photos). The crack
runs almost vertical. The same affect is seen from cracks
made by the sun. Should the tree show a weakening vitality,
it should be evaluated. Images
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| Fungi |
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| With
the hypha (mycelia), fungi penetrate the wood and deplete the
wood of nutrients, most importantly cellulose, polysaccharide,
lignin, minerals, carbohydrates, lipids and protein. If the
tree is affected then it should be evaluated. More
tree fungi. |
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| Galls |
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| Galls
are caused mostly by gall mites. Affected mostly are the leaves
of trees. Less affected are the buds, sprouts, blossoms, or
branches. The distortion of the leaf does not look very good
but it is not dangerous to the tree. Apart from the gall mites
there are other pathogens, for example, the gall wasp. Detailed
information can be found here or in the index of deciduous trees. |
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| Growth |
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| Growth
attached to a tree, such as, ivy, grapevines, and other plants
do not harm the tree. If a growth becomes so prevalent that
the assimilation of the tree becomes affected, then the growth
should be removed. Image |
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| Insect
leaf damage |
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| Insect
leaf damage: Through insects like the June bug, caterpillar,
and others, a tree may lose a great amount of leaves. Normally
this does not pose a danger to the tree. But if a tree gets
eaten bare year after year, this can affect the tree’s vitality.
Image |
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| Lichens |
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| Lichens
are a symbiosis between a fungus and algae. Mostly it is tubular
fungi and blue or green algae that form a living community.
They also grow in extreme circumstances, but they need light
and moisture. Lichens do not pose any danger to a tree. Images |
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| Malignant
growths |
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| Malignant
growths are caused by earth rays, bacteria, and fungi. They
can be life threatening to a tree. To find out the exact cause,
an expert should be consulted. Image |
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| Mildew |
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| Mildew
is a white covering over the leaves that can be wiped off with
the fingers. In extreme cases, it should be brought under control.
Images |
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| Mistletoe
(Viscum album) |
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| The
mistletoe is an evergreen semi-parasite that takes away water
and nutrients from the tree. An extreme case can cause a tree
to die. Images |
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| Mites |
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| Mites
belong to the arachnid group. They are only 0,1mm – 0,5mm big
and are equipped with a sting and suction ability. They affect
leaves and buds. Affected leaves dry out. Extreme cases can
cause the tree to weaken. |
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| Moist
Crack |
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| A
moist crack in a tree trunk indicates decay within the trunk.
The tree should be evaluated. Image |
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| Red
Pustules (Nectria cinnabarina) |
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| Red
pustules are parasites in the wound that cause wilting of leaves
and shoots. The orange-red boils appear in fall and winter.
Affected areas should be cut back to the healthy stem. Images |
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| Sap |
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| Sap
is a natural defense mechanism of a tree against damage. Image |
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| Shield-lice |
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| Shield-lice
attack and damage the bark characteristics. This causes moistness
in the bark. Some shield-lice also attack the leaves. Because
of their tiny size, they can often be identified only after
they have formed a shield-like spot with their waxy excretions.
In extreme cases, an expert should be consulted. |
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| Shoots
from a trunk |
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| Shoots
from a trunk often indicate a disturbance in the tree. This
can be diverse. In an extreme outbreak of shoots, consult an
expert. Images |
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| Tubers |
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| Tubers
are growths that are caused by fungi, insects, or other environmental
influences. These are not dangerous for the tree. Image |
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| witches'
besom |
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| witches'
besom are caused through viruses or fungi. These are not dangerous
to the tree. Images |
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| Wood
Destroying Insects |
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| The
spectrum of wood destroying insects is very large. Frequently
it is the larva of insects breeding in wood that damage the
bark and parts of the wood core, which gives fungi the opportunity
to infest a tree. An evaluation from an expert is advisable.
Images |
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| Woodpeckers |
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| Woodpeckers
build their nests mostly in trees with tree rot. Tree rot is
an indicator of fungal decay. The tree should be inspected.
Images |
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