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10 Common Diseases in Aspen Trees and How to Treat Them

10 Common Diseases in Aspen Trees and How to Treat Them
The domestic plantation of aspen trees has increased in recent times. The aspen tree is afflicted by many diseases, though not all are fatally harmful. This post lists a few common aspen tree diseases, and ways how to treat them.
Anup Patwardhan
Last Updated: May 13, 2018
Did You Know?
Aspen trees have mythological significance. The tree's name in Greek, 'Aspis', means 'shield'. It is also used as a symbol of Christmas holidays in many parts of the world.
Aspen trees were not the most preferred trees for home decoration in the past. There has however been a change in this trend in recent times, as more and more people now plant aspen trees as part of their home decoration. These trees are fast growing and the leaves develop a beautiful color in autumn.
Aspen leaves are short and have a flat stem. Even the slightest of breeze is sufficient to ruffle them around. This has led to the tree being famously known as the quaking aspen. The scientific name of the tree, Populus Tremuloides, has made is famous as the trembling aspen.
Aspen in Plant Kingdom
Kingdom Plantae
Order Malpighiales
Family Salicaceae
Genus Populus
Section Populus
Species Populus Tremuloides
Aspen Tree Diseases
Aphids on aspen leaves
Aphids are also known as plant lice. These are small insects and affect the stem, trunk, and developing leaves. Aphids feed on the plant sap. It is the fluid that carries sugar and other nutrients that are required for plant growth. The growth of the plant is affected when the aphids remove their sap.
Ants are attracted to the honeydew that the aphids secrete. Their presence on the aspen tree is more often than not a sign of aphids infecting the tree. Decreased growth can be a symptom of aphids feeding on the plant sap. The leaves of aphid-infested trees turn yellow and are curled. The presence of sooty mold fungus can also be a sign of aphid infection.
You can use neem oil, oil from the Indian Lilac, as an organic pesticide to get rid of an aphid infestation. This interferes with the mating habits of the aphids and controls the overall population. There may be a need to use this treatment more than once. You can also facilitate aphid predators like ladybugs and lacewings an access to the infested plant. This will reduce the aphid population drastically.
Marssonina Blight
Marssonina blight on aspen leaves
This is a fungal disease caused by marssonina brunnea and marssonina populi. This disease is dependent on weather conditions, and its severity differs each year.

Marssonina blight, at the beginning, leads to the formation of small, brown spots on the leaves. These spots enlarge with the progression of the disease. The spots may be vein-limited. This disease may lead to the defoliation of the aspen tree.
Sever the affected part of the tree. Make use of fungicide as a preventive measure before the outbreak of the disease. Keep sufficient distance between two trees so as to allow air circulation and restrict the spread of the disease. Also, do not allow moisture to gather on the surface of the leaves. A variety of aspen trees that is resistant to this fungal attack can be planted.
Aspen Leaf Miners
Aspen leaf miner
Aspen leaf miners are types of moths. These insects form and grow within the aspen leaves. They feed on the interior tissue of the leaves. It may not be a fatal disease, but the spots caused by the moths ruin the beauty of the leaves of this tree.

The leaves dry out when they are infested with leaf miners. They may fall off or turn brown in color.
The presence of insects will need spraying of insecticide, However, it will have very little effect in case of large-scale infestation. You can treat the infection by using insecticides that find their way through the root system of the plant.
Cytospora is a fungal disease. This is caused by the cytospora cankers fungus. This fungus is active in hot and humid conditions, and dormant in cold weather conditions. This is a fatal disease.

This fungus infestation may lead to the discoloration of the aspen tree. It may also cause an orange-colored liquid to ooze from it. This is a result of the spores of the fungus.
If infected, dispose off the affected area of the tree, and provide proper sanitation. The fungus infestation can be avoided by planting a resistant variety of the tree.
Trunk Rot
Polypore fungus on aspen tree
A trunk rot in aspen is caused due to Phellinus Tremulae. This is a species of polypore fungus.

One of the primary symptoms of the tree being infected by this fungus is the loss of its volume. Trunk rot causes holes in the aspen tree that are used by birds for nesting. Hence, you will find bird nests in the tree.
Plant the variety of aspen that is resistant to trunk rot. Remove the affected area of the tree, if possible, like in case of various other diseases. There is no specific remedy for this disease, thus giving the preventive measures more importance.
Oystershell Scales
The scales attach themselves to the tree bark or branch. They, like aphids, feed on the sap of the tree, and kill the tree over time. The scales have a brownish color which is very similar to the bark of the tree, and can easily be overlooked.
Upon infestation, there is a formation of folds in the affected limb of the tree. This means that there will be irregular curves or bends in it. The oystershell scales can be easy to overlook, but not the injury that they inflict on the tree.
Oystershell scale infestation can be brought under control with the help of wasps that feed on them. If the infested area is small, then that portion of the tree can be scrubbed to get rid of the infestation. Insecticides can also be used to bring the infestation under control.
Ink Spot Disease
Ink spot disease is caused by a fungus named ciborinia. It can damage the growth of the tree.

As a result of infection by this fungus, brown spots start appearing on the leaves of the tree. The spots are similar to the spots caused by leaf miners. These spots fall off and leave a hole in the leaves.
In case of this disease, fungicides are effective only for prevention purposes. Proper distance between trees can limit the damage caused by this infestation. Cut off the infected leaves before the problem spreads.
Sooty Bark Canker
Sooty bark canker is a fungal disease. This is caused by encoelia pruinosa. This disease is fatal for aspen trees.

There may appear a dead patch on the bark that grows with time. The infected bark becomes 'sooty. The bark then starts to wither.

Remove the limb that is infected with the disease. Make use of copper fungicides. Also paint the tree exposed to direct sunlight to prevent sunburn. When painting the tree, use white latex paint.
Black Canker
Like sooty bark canker, black canker is also a fungal disease. This is caused by ceratocystis fimbriata. This disease has a very slow progression, and is not fatal for the aspen trees.

The symptoms of this disease are similar to sooty bark canker disease. There is appearance of a small dead spot on the tree, that, after years of infestation results in a huge canker. Spores appear at the infected area which are difficult to see. These spores ooze out as a sticky mass.
No major control measures are known against black canker. Avoid any wounding of the tree in its growth years. If removing the infected area is the only option, then leave the infection untreated, as this disease is not fatal.
Elk Scarring
Elk scarring on aspen tree
Elks scar aspen trees and wound them. This opens up the risk of the tree being host to a range of harmful diseases.

The tree is susceptible to infection. Also, there will be wound marks present towards the base of the tree.

Use chemical deterrents or repellents to avoid elks from browsing on the tree surface. Fencing can also be an effective way to manage and limit the damage caused by elks.
Marssonina Blight and Ink Spot Disease are fungal infestations and result in a 'black leaf' problem in aspen trees. The roots of a towering aspen are very invasive. So take care not to plant these trees too close to your home.