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Guide to Common Tree Diseases and Pests in Colorado

Healthy trees

Tree Diseases

Trees are very much like humans and animals in the fact that they can be susceptible to disease. There are many factors that can lead to a diseased tree to include planting location, weather, soil conditions, and insect carriers.  Most tree diseases will not lead to tree mortality but if not treated can lead to added stress in the tree.

Bacterial Wetwood

This flora-based disease, also called slime flux, attacks the center core or bark portions of different types of deciduous trees. The disease is most commonly found in elm, cottonwood, aspen, and willow trees. The slime the disease produces is toxic to the tree's cambium layer where the plant produces new cells and therefore may prevent new growth.

Bacterial Wetwood can be identified by the presence of yellow-brown discolorations on the trunks, bark, and branches. The areas will appear to be moist and will sometimes be oozing. The slime ooze may have an unpleasant odor and is likely to attract unwanted insects to your yard. When this material dries, it will turn more of a gray color.


Canker is a common tree disease in this area that can affect any landscape tree. It is characterized by dieback of branches, with oozing appearing from under the bark on branches and sometimes on the primary stem of the tree. If left untreated, the branches will die completely – threatening the health and life of the entire tree.

Fire Blight

Fire Blight is a serious, bacterial-based disease that is common in ornamental flowering trees, such as apple trees, ornamental crabapple trees, pear trees, mountain ash, cotoneasters, and other various types of ornamentals. The Fire Blight-causing bacteria is spread by birds, raindrops, and pollinators – especially by insects who spread the bacteria from tree to tree. As a result, Fire Blight can spread quickly – and can kill several trees on a single property.

Leaf Diseases

While seemingly less damaging, a host of different leaf diseases are common in the Colorado Springs area. These diseases may seem to be just cosmetic, but they can quickly become more serious diseases that affect the health of the entire tree. To best identify what disease is targeting your trees’ foliage, have one of our Tree Disease Specialists inspect your property.

Other Diseases

Integrated treats a host of other diseases – just call us at the first sign of a problem or a disease. Our Tree Disease Experts will respond quickly, setting up an appointment to promptly visit your property and to analyze your tree’s problems – prescribing a treatment plan that will help your tree return to full health.

Tree Pests

In addition to diseases, your trees are susceptible to a variety of pests that can attack and infest your property, causing the trees to sustain lasting damage or even die off entirely.


Aphids are tiny, soft-bodied, pear-shaped insects that are found clustered together on the leaves and needles of trees and shrubs. Aphids will attack a wide variety of tree and shrub species. These insects are commonly found on ash, aspen, apple, linden, certain conifer species, and many other ornamental trees and shrubs. Some aphids spend their entire life on one plant while others go from plant to plant. An aphid population can also increase in numbers very quickly, making dealing with them a top priority for any lawn care-oriented household.

Bark Beetle

A vast majority of bark beetles native to North America are found in our forests, landscapes, and urban environments. A number of these particular insects can cause large swaths of tree mortality if not properly controlled. Bark Beetles get their name because they reproduce in the inner bark layer of the tree whether the tissue is living or dead. The insect will live and feed between the bark and the wood of various species of trees with some attacking only a certain species of tree and others being less picky. Bark Beetles will often attack trees that are already weakened by disease, physical damage, and drought, making proper lawn and tree care on your property the best first line of defense. Healthy trees will produce a resin that will in most cases provide a natural defense against the beetles. Because of large outbreaks in the Rocky Mountain Region surrounding the Mountain Pine Beetle and other beetle species, we have established a preventative management plan to protect your trees from attack.

Douglas-Fir Tussock Moth

The caterpillars of the Douglas-fir Tussock moth chew on the needles of spruces, douglas fir, and true firs. The young caterpillars have long black/grey hair turning brightly colored as they mature. A mature larva is 1-1.5 inches long with a grayish-brown body and a black head. The moth spends the winter as an egg within an egg mass. In the early spring, it will hatch and slowly move to feed on the new growth of the tree. This occurs shortly after bud break, usually in the month of May. By mid-summer, the larvae become full-grown and in most cases migrate away from the infested tree. At this time they pupate in close proximity to the infested trees and emerge in late summer to begin the cycle again.

Emerald Ash Borer

Emerald Ash Borer is a green jewel beetle native to eastern Asia that feeds on certain ash species. Adults are dark metallic green in color with a red or purple abdomen under the wings. The insect is about 1/2-inch long and 1/8-inch wide. The larvae of this particular insect are white in color. The Emerald Ash Borer is very destructive and can infest and kill numerous true ash species.  The larval stage of this insect feeds under the bark of the tree cutting off the flow of required water and nutrients. Infested trees will slowly die over a period of time usually taking two to four years before mortality.

IPS Beetle

IPS Beetles are most commonly referred to as engraver beetles.  These particular beetles attack pine and spruce trees. IPS Beetles are small red, brown, and black beetles about 1/8 inch-3/8 inch long. This particular insect has a cavity in the back portion of its body that has 3-6 pairs of tooth-like spines which distinguishes them from other bark beetles.

Lilac/Ash Borer

There are several species of lilac/ash borers that are guilty of wood-boring in the greater Colorado Springs landscape. These particular borers will feed on ash, birch, fir, oak, and pine, as well as various stone fruit trees. Their larvae are white-bodied with a black head and are between 1-1.5 inches long at maturity. They pupate into moths. The adult moths will have long, narrow front wings and shorter, wider, back wings. In the adult stage, the moth closely resembles a yellowjacket or paper wasp.

Mountain Pine Beetle

The Mountain Pine Beetle is a pest native to forests in the western region of North America. Attacks of this particular insect are responsible for the loss of millions of pine trees. The beetle has a hard, black exoskeleton and is about the size of a grain of rice. Following the egg hatch, the larvae tunnel under the bark away from the egg gallery producing a distinct feeding pattern. The Mountain Pine Beetle has a one-year life cycle in Colorado and often kills large numbers of trees annually during its destructive outbreaks.

How to Prevent Tree Diseases and Pests


Watering your trees and shrubs is the single most important aspect of keeping them healthy and thriving. Most homeowners and business owners forget about supplementing their trees and shrubs with water during the winter and even the summer months. In most cases, lawn and drip irrigation do not deliver the amount of supplemental water that a tree or shrub needs to stay healthy and survive in the dynamic Colorado climate. When irrigation systems are turned off for the winter months and natural precipitation is minimal, the trees will continue to struggle with maintaining a healthy root system.

Fall and Winter watering should be performed in the months of October-March. Watering should be performed one to two times per month depending on weather and precipitation amounts. Winter watering is best applied when temperatures are above 40 degrees. Summer watering is done in the months of April-September and should be performed at least three times per month. Trees planted in non-turf areas will need extra watering if drip or lawn irrigation is not sufficient.


There are various different types of tree spraying that target a broad range of insects, diseases, tree transpiration, and growth. The method of application can be performed using either a hand-pump style spray device that is very low volume or a large commercial spray system that can cover larger trees at different heights. Each spray application is designed to target a specific pest and different spray techniques may be used for each. One being a foliar-type spray that concentrates on the canopy of the tree and controls a wide variety of leaf sucking insects. Other methods of spraying may concentrate on the trunk and bark of the tree to prevent any borer-type pests. There are also specialized sprays that help control the disease as well as regulate transpiration or moisture loss in the tree. Trees and Shrubs may also be sprayed with a growth regulator to help control crown and branch growth.

Deep Root Fertilization

The soil types in Colorado Springs tend to bind up important nutrients in the soil, making it difficult for trees and shrubs to get the nutrients they need to maintain their health and mature. Additionally, the arid dry climate in the area doesn’t encourage the formation of healthy, nutrient-rich soils. By keeping your trees fertilized by replenishing nutrients in the soil, you prevent a host of diseases and related problems that can arise from a lack of nutrients. 

If Your Trees are Showing Signs of Disease or Infestation…Call Us Right Away!

Our team of experts at Integrated Lawn Care understands that the trees on your property are precious to you. Apart from being a sizable investment, they also beautify your home and provide shade and ornamentation for your home.

When your trees begin to display signs of a disease, let our tree disease specialists provide curative measures to help save your trees.

In addition to treating your trees for disease, we also set up a program of Deep Root Fertilization that will help prevent your trees from getting diseases in the future. This long-view approach helps you avoid any problems in the future – saving your investment and helping your trees continue in good health for years to come.