| Steamboat
Springs District -
Insects and Disease
There are many insects and
disease concerns throughout the district.
Listed below are some of the most common:
Bark Beetles
. White Pine Weevil . Poplar
Borers . Aspen Leaf Spots
. Others
Note: You
will need Acrobat
5.0, or higher to open the following PDF files.
Bark Beetles
Bark beetles are insects that feed
on the cambium (the layer beneath the bark) of
trees. Most bark beetles breed in trees that are
severely stressed or dying. A few beetles are
capable of killing trees, either through mass
attacks and/or through the introduction of disease
causing-fungi. The two most critical beetles on
the Steamboat District are mountain pine beetle
and spruce beetle. Are your
trees at risk?
Mountain pine beetle (MPB)
is prevalent throughout Jackson and Routt
County and increasing annually. MPB only affects
larger (i.e., >8 inches in diameter) mature
lodgepole pine or ponderosa pine trees. Current
areas of concern include:
-
Jackson County - the area
around Rand and northwest of Walden.
-
Routt County - the Morrison
Creek drainage, Lynx Pass area, Fish Creek
Drainage, Soda Creek Highlands Subdivision,
Steamboat Ski Area, Steamboat Lake area and
Seedhouse Road area.
Signs and Symptoms
-
Popcorn-shaped masses of
resin, called pitch tubes, on the trunk.
-
Reddish boring dust in
bark crevices or adjacent to the tree base.
-
Reddish needles (crowns
of successfully attacked trees usually turn
off-color beginning in May or June following
the previous summer).
Control & Prevention
-
Maintaining a healthy, vigorous
tree or stand is most important.
-
Natural controls include woodpeckers
and a few insects (limited application during
high levels of attack).
-
Infested logs can be treated
in various ways to kill developing beetles:
-
Burning, removing bark,
burying, or intense solar radiation.
-
Chemical options, unfortunately,
are greatly limited: Chemical prevention
options are limited to carbaryl (Sevin)
and permithrin (Astro).These chemicals
are applied to living trees in early summer
prior to beetle emergence.
Spruce beetle (SB)
is similar to mountain pine beetle in all aspects
expect one. Where spruce beetle differs is that
they typically prefer blowdown material. Therefore,
under normal circumstances they don't attack live
trees.
Because of the Routt Divide Blowdown
a spruce beetle epidemic is currently occurring.
We can expect to see beetles eventually attacking
live trees as they start leaving the main blowdown
area in search of suitable standing hosts. Current
areas of concern for the spruce beetle are the
Buffalo Pass area, Rabbit Ears area, Seedhouse
Road area, and the Steamboat Ski Area.
Additional Information
MPB
Fact Sheet (180 KB PDF)
SB
Insect and Disease Leaflet
Steamboat Springs District
Prevention/Control Summary & Contractor
List
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Steamboat Springs
District Main Page
White Pine Weevil
White pine weevil is sometimes the most serious
insect pest to Colorado blue spruce in landscape
plantings. The insect larvae feed underneath the
spruce leader, thus girdling the plant and causing
a stunted top. Once the top leader is killed some
side branches will begin growing skyward to replace
the old terminal leader. If successful, begin
training the best one by removing other competing
branches so there is only one new terminal leader.
Insecticides that are applied in the spring when
the weevils feed and lay eggs can provide control
for that year. Standard bark beetle or wood borer
insecticides (Sevin, Dursban, Astro) applied at
the recommend rates should provide control. Application
will need to occur annually to prevent annual
attacks.
Additional Information
White
Pine Weevil Insect and Disease Leaflet
Top
Steamboat Springs
District Main Page
Poplar Borers
Poplar borers primarily affect aspen, but cottonwood
and poplar can also be hosts. Damage is associated
with moist areas of bark, usually with sawdust.
This is the result of the insect tunneling into
the sapwood. Chronically infected trees exhibit
a black varnish-like stain on the bark below points
of attack.
Control: Because of the long life cycle, poplar
borer is difficult to control. Standard borer
treatment of insecticides (Sevin) applied to the
trunk should provide coverage throughout the activity.
Application to existing areas of attack (where
egg laying is concentrated) should be thorough.
Additional Information
Shade
Tree Borer Fact Sheet (216
KB PDF)
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Steamboat Springs
District Main Page
Aspen Leaf Spots
Several types of fungi can cause spots on aspen
leaves. None of these are detrimental to aspens
unless several consecutive years of defoliation
occur. The best method of control and prevention
is by removing the infected leaves on the ground
to reduce available spores for future spread.
Additional Information
Leaf
Spot Fact Sheet (111 KB PDF)
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Steamboat Springs
District Main Page
Other Insects and Diseases
Many other insects and disease naturally occur
throughout the state of Colorado. Please check
out the following links for additional information:
Colorado State Forest
Service: Insects & Diseases information
page
Insects that Feed on Trees and Shrubs
(3.14 MB PDF)
CSU
Cooperative Extension Service
USFS
Forest Health Site
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