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Oak Wilt
Issues Confused with Oak Wilt
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Oak Wilt is commonly misdiagnosed. There are a number of problems
that afflict oaks, unrelated to Oak Wilt. The protocol to treat
these problems is different than treatment
for Oak Wilt. If you determine your tree is suffering from one
of these ailments, call a qualified consulting arborist for treatment
recommendations.
Injury Caused by Human Activities
The most common injury to oaks caused by the activities of people
fall into three primary categories. Changes in soil grade, soil
compaction, and cut roots. Symptoms usually include thin crowns
and die back.
Soil Compaction
Forest soils are loose and fluffy allowing roots to grow and replace
themselves easily. Gas and water exchanges freely which allows a
tree to grow optimally. Soil compaction results from soil particles
being pressed together. This interrupts the free flow of moisture
and gas exchange, and inhibits root growth. Trees that are growing
in these conditions become inefficient and are less able to respirate.
They often begin to slowly decline as they use more energy than
they are able to manufacture. If they have low energy reserves when
the compaction takes place, they usually will die within a couple
of years. Trees with higher energy reserves can live for as long
as 10 years. This of course all depends on the degree of compaction.
To help trees growing in these conditions you must replace the soil
and give the tree new soil to grow it's roots. This is usually done
with a large drill which removes cores of soil and replaces the
soil. We call the process soil
replacement therapy. |
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 Urban
yards often have soil compaction that slowly causes the trees
that live there to be weak and vulnerable to environmental changes
such as drought. They are often taken advantage of by opportunistic
diseases and insects. |
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Changes in Soil
Grade
Roots of trees grow near the surface of the soil. These "feeder" roots are often in the top few inches of the forest floor and your
yard. They absorb water, oxygen and minerals from the soil that are
used in the day to day life system of the tree. When additional soil
is added over the top of tree roots they are, in effect, suffocated.
Added soil is often denser and more compacted than the original soil.
This prevents the tree from establishing new roots. Ultimately the
tree will die from this. Sometimes the decline and death can take
many years. The best remedy is to remove the added soil and do a process
called soil replacement therapy. |
Adding
soil under a tree will bury the roots. This will cause a reduction
in water and gas exchange. This will cause trees to decline
and die. |
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Cut Roots
Roots get cut for various reasons. Situations include utility replacement,
home construction, sidewalk repair, sprinkler installation, and
other reasons. Because most tree roots grow in the top 12 inches
of the soil, the cut does not have to be deep to injure the tree.
Severe root loss will show up as dehydration – which happens
quickly as the tree dries out and wilts. Less severe root loss will
show up as crown dieback in future years. If roots on your tree
have been cut, there is little that can be done. Make sure the soil
is not compacted (see above) so the roots
can grow back. Water more often during dry spells.
Boring Insects
Boring Insects can cause a great deal of damage to a tree very quickly
as they consume the trees water and food conducting tissue. Healthy
trees have natural defenses that are very effective in preventing
borer attacks, thus if borers are attacking your tree it has been
weakened by another situation. (Note: There are a few highly aggressive
boring insects including the Emerald ash borer and the Asian longhorn
beetle, which are both introduced from Asia. However these are rare
and isolated to very specific areas of the country). The symptoms
of borer attacks is dieback that starts in the top of the tree.
The leaf symptoms are different than oak wilt symptoms in that the
leaves remain stuck to the branches, while the leaves when associated
with oak wilt fall off the tree. Check with a highly trained arborist
to set up a treatment protocol and diagnosis to uncover the cause
of why your tree is weak enough to be attacked by borers. |
Roots
are often cut when utilities or sprinkler systems are installed.
This can cause serious problems which show up as dieback or
tree death. |
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Boring
insects invade trees that have been weakened by other factors.
Notice that the dead and dying leaves are still attached to
the tree. They will also attack trees infected with Oak Wilt.
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