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Frequently
Asked Questions on Dutch Elm Disease and Treatment
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What
is Dutch elm disease?
How
does it spread?
Are
my trees already infected?
How
can I protect my trees?
Are
all elms susceptible?
Can
I save my diseased tree?
Will
my tree look different after the injection?
How
long will my tree be protected after it is injected?
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What
is Dutch elm disease?
Dutch
elm disease is caused by a fungus that lives in the sap-conducting
vessels of infected elm trees. While in the sapwood, the fungus
spreads rapidly, producing a toxin which causes the tree to
plug itself up, blocking the transport of sap, resulting in
wilting leaves and rapid tree death. Return
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How
does it spread?
Elm bark beetles inadvertently deposit DED fungal spores while
burrowing into young branch crotches to feed. Spores are picked
up on their backs after feeding on diseased trees, and as they
burrow into a healthy tree, inoculate it with the fungus creating
a new infection.
Besides
an ‘above-ground’ infection caused by elm bark beetles,
DED may also be spread through grafted roots from elms grown
in proximity to each other. Their overlapping root systems often
encounter each other and form a graft, sharing water, nutrients
and potentially, DED.
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Are
my trees already infected?
DED
symptoms usually begin to develop 4-6 weeks after infection.
Sudden and severe wilting is a typical and often obvious early
summer symptom. Leaves curl and dry before turning brown while
still on the branch. As the season progresses, leaves may fade
and turn yellow before falling, often in great numbers. When
the bark of an infected branch is peeled back, brown to bluish-brown
streaking or mottling often appears on the outer layer of wood.
Return
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How
can I protect my trees?
For
particularly valuable landscape specimens, preventive systemic
fungicide injections are our most useful tool. Top Notch Treecare
has developed an intensive DED management program that is second
to none. Return
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Are
all elms susceptible?
All
species of elm are to some extent susceptible, but the native
elms are the most affected by DED. Because of its aggressive
nature in the wild and previous wide use in the landscape,
the American elm has suffered the brunt of the damage. Return
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Can
I save my diseased tree?
Diseased
elms whose symptoms are caught very early and under the right
circumstances, can be injected therapeutically. It is also
critical that pruning be done to remove the infected branch,
while following up the next growing season with a ‘booster’
shot of the fungicide. In some cases, it can take a few seasons
before symptoms are noticeable, as they often lag behind the
advance of the fungus. Early diagnosis is critical.
When
infections become systemic and a root graft transmission is
a threat, barriers that cut the grafted roots can sometimes
be dug with a trencher or vibratory plow. Return
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Will
my tree look different after the injection?
Less
than one percent of injected elms have a phytotoxic reaction
to the injection with subsequent leaf drop. Top Notch has
not had a single elm die from this reaction. As a point of
reference it is useful to compare other elms in your neighborhood
to see if their appearance is similar to your tree. The best
way to minimize the chance of this unsightly reaction is to
make sure areas under the tree’s canopy are well watered,
especially in dry periods. Return
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How
long will my tree be protected after it is injected?
Generally
speaking, injected trees are protected for three growing seasons,
including the season in which it is injected. Your arborist
will determine the appropriate duration of protection factoring
in local, neighborhood and area-wide disease trends. Return
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