Mountain Pine Beetle - is always present in the Colorado forest. In the past few years the pine beetle population has been on the rise. We are now in an epidemic stage. Visit our page devoted to controlling mountain pine beetle. Spray susceptible lodgepole pine trees with a preventive spray in May, June or July.
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White Pine Weevil – feed on the terminal shoot of Englemann spruce and blue spruce. Resin oozing from tiny holes in the leader is the first sign of weevil attack. Eventually the tip bends over and turns brown. Spray in spring before bud break and in the fall for this insect. Prune out infested tops.
Cooley Spruce Gall Aphid - Cooley spruce Galls are common and conspicuous on blue spruce. Although they cause esthetic damage and can cause disfigurement in the crown, they have little effect on tree health. Spray in Spring and again in Fall to prevent new galls from forming.
Pine-Needle Scale- feeds on the needles of most species of pines, spruce and fir. During outbreaks, needles may be nearly covered with the bodies of the scales, giving an appearance that the plant is spattered with white paint Spray in Late April to late May.
Pine-Needle Scale
Ips Beetles -
are
a common group of bark beetles that infest pine and spruce trees. IPS
rarely attacks healthy trees. Most problems with IPS occur to newly
transplanted conifers or when trees are under stress, such as from Dwarf
Mistletoe or construction. Several generations of IPS can occur 
in
a season. Spray early in the season before beetles get active.
Ips Beetle Damage
Poplar Borer- is becoming the most destructive insect to aspen trees in Eagle County. This insect “honeycombs” the branches and trunk leaving it weak and susceptible to failure in windstorms. A dark varnish like stain develops below borer attack points. Spray in spring or late July.
Poplar Borer
Aspen Leaf Blights
Aspen trees prone to multitude of foliage disease caused by a host of fungi. Occasionally, a severe outbreak will cause premature defoliation or dieback of parts of the tree. If the defoliation occurs early in the season, a second growth of foliage may appear and the health of the tree should not be seriously affected. Loss of leaves in midsummer followed by subsequent refoliation could prevent the tree from completely hardening off prior to cold weather. It can also reduce the amount of food stored, leading to increased danger of frost, reduced growth and vulnerability to other insects and diseases. When leaves are lost late in the season, the tree will not refoliate.
Managing foliage disease effectively relies primarily on sanitation. Removal of the infected leaves, twigs and branches in the fall may reduce the amount of disease the following spring. Fungicides can also prevent foliage diseases, however it will only prevent new infections, any leaves already infected will not be cured. Sprays should be done at bud break which normally occurs late May to early June. A second application is highly advisable during the growing season at a 12-14 day interval from the time of the first spray.
Four fungi affecting aspens in Colorado
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Marssonina - identified by dark brown flecks with yellow halos. Mature spots characteristically have a white center. Severely infected leaves may have spots fused. |
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Ciborinia - commonly known as ink spot. Appears as tan to brown areas on upper leaf surfaces late spring to early summer, may become totally brown by mid-summer. Eventually, raised, oval shaped, black masses form on affected leaves, falling out in late summer. Especially prevalent in dense stands of aspen. |
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Venturia - brown to black irregular shaped areas showing in early spring on leaves near shoots infected the previous season. Leaves eventually become dry and distorted. Typically spreads to new shoots, blackening and curling to resemble a shepherd's crook. |
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Melampsora - recognizable by small yellow-orange pustules on lower leaf surfaces. Though common, it rarely causes serious problems. |
Dwarf Mistletoe - The Facts
There are many misconceptions about Dwarf Mistletoe. The most common one we hear is "My neighbor says you can't do anything about it, your trees will just die." This is far from the truth. Here are some facts about Dwarf Mistletoe:
Dwarf Mistletoe is a major problem in Colorado forests on Ponderosa and Lodgepole Pine. It is a small, parasitic flowering plant. The plant grows into the bark and phloem of the tree, where it produces “roots” called sinkers which provide the parasite with water and nutrients. This process kills the tree slowly by robbing it of its' food and water. New plants are formed by an amazing phenomenon where seeds are explosively discharged at up to 60 m.p.h. into surrounding branches and neighboring trees.
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Dwarf Mistletoe is easily identified by the yellow to green to brownish-green shoots that protrude from the infected part of the tree. Other signs of infestation are reduced foliage, yellowish or brownish foliage, and "witches brooms" - distorted branches the form clumps of foliage.
Dwarf Mistletoe Management is four pronged:
- If infestation is not too severe, pruning out of infested branches is recommended.
- If the infestation is severe and the tree is near death, removal of the tree(s) is usually recommended (See rating chart).
- Plant non-susceptible species such as spruce, Douglas- fir and aspen to maintain tree growth in the area. Maintain maximum tree and forest health through thinning and sanitation cutting to remove trees near death. As trees weaken they become very susceptible to Ips and Pine Beetle.
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If you are having problems with Dwarf Mistletoe, please don't hesitate to call for a consultation.
Dwarf Mistletoe Rating System
