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While it's usually easy to spot a sick tree, it can be more challenging to determine if it’s merely unhealthy or truly dead. Check out more photos of trees to help you decide.
Nousha/iStockphoto.comA dead tree can be just as striking as a vibrant, blooming one. As poet Joyce Kilmer beautifully wrote, 'I think that I shall never see, a poem lovely as a tree.' In the fall, the leaves of deciduous trees transform from green to brilliant reds, yellows, and oranges.
For those in the Eastern United States, taking weekend trips to admire the colorful autumn foliage is a must. In winter, those leaves turn brittle and brown, eventually falling to the ground to be gathered up and either bagged or recycled into mulch.
When spring arrives, the trees come back to life, their green leaves reappearing and flowering trees turning into stunning displays. This is the natural cycle of a healthy tree. In addition to enhancing the landscape, trees provide oxygen, shade, and shelter for insects, birds, and animals.
A healthy tree possesses an incredible ability to adapt, survive, and endure even the harshest conditions. Like humans, trees are living beings that can get sick and eventually die.
Tree diseases can bring down even the strongest oak or redwood, though many trees fight back, much like a person battling a serious illness. It's rare to find a completely disease-free tree due to the many microscopic organisms living on its bark and in its root system. However, trees are resilient and usually manage to live alongside these pathogens.
At times, tree disease can take hold so severely that recovery becomes impossible. When this occurs, the tree becomes vulnerable to further diseases, and if it can't recover, humans may need to intervene. But just like a doctor with a patient, sometimes a tree's condition is beyond saving, and it turns into a danger.
A dead or dying tree in your yard can fall on your home, creating a whole new set of issues. When trees are beyond saving, removal becomes necessary. This article explores some common tree diseases, how they're diagnosed, and what steps can be taken to save a sick tree.
Common Tree Diseases
Trees can suffer from a wide range of diseases, many of which are specific to certain species. One such disease, Anthracnose, targets hardwood trees like American sycamores, white oaks, dogwoods, and black walnuts. It is particularly common in the eastern United States, where these tree families thrive.
Typical signs of Anthracnose include dark, discolored spots or dead areas on the leaves, also known as leaf blight. This disease is caused by several types of fungi that spread through spores, which are tiny, airborne particles, especially during windy or rainy weather.
For spores to germinate, wet conditions are required, which is why Anthracnose thrives in years with prolonged rain. While a single infection of Anthracnose won’t usually kill a tree, repeated defoliation weakens it, making it more vulnerable to other diseases. Its greatest impact is seen in the reduction of shade trees in urban settings.
Root decay, or root rot, is another frequent cause of disease or death in trees. Roots anchor the tree and provide nutrients and water, with larger root systems found in older trees.
Trees suffering from root issues can easily be toppled by wind or even collapse unexpectedly under the weight of their own leaves. It's difficult to spot root decay, but there are two clear signs: broken roots or visible fungus growth.
One of the most destructive tree diseases is chestnut blight, a fungus that has nearly eradicated the American chestnut from eastern forests. The fungus spreads through spores carried by wind and rain, infecting fresh wounds in the tree's bark and causing cankers.
The fungus appears during damp conditions and looks like an orange, curled horn. While no cure has been found yet, scientists are actively researching ways to develop a disease-resistant chestnut tree.
Is Your Tree Dead or Just Sick?
A healthy tree is strong and resilient, but it can face challenges from a variety of factors. Weather conditions such as wind, rain, extreme heat, and cold can harm trees. Since we can't control these environmental elements, it's important to watch for early signs of illness.
Trees should be inspected regularly, ideally once a season and especially after storms. A healthy tree will have a full crown, which refers to the spread of branches and leaves. However, don't be deceived by green foliage—trees can still appear lush while being unhealthy. Look out for these common signs that your tree might not be well.
- Dead wood: Dead wood appears dry and brittle, breaking with little effort. Unlike healthy branches that can bend in the wind, dead wood is prone to snapping. These dead branches, known as widow makers, pose a significant danger and must be removed immediately.
- Cracks and cankers: Vertical cracks are deep splits in the bark, often signaling a failing tree. Cankers are open wounds in the bark, and they increase the risk of the tree's stem breaking near the canker.
- Weak branch unions: These are areas where branches are poorly connected to the tree, typically due to two branches growing too close together. The bark between them is weaker than wood and compromises the strength of the branch union.
- Decay: Trees typically decay from the inside, making it hard to detect early on. Indicators like fungi, such as mushrooms, peeling bark, and soft or crumbling wood can signal internal decay.
- Poor tree architecture: Poor tree architecture refers to uneven growth, such as a tree leaning in a particular direction or having a lopsided shape. This often results from years of storm damage or improper pruning.
If you suspect your tree may be in trouble, it's best to consult an arborist. Arborists are experts who can accurately diagnose tree diseases and recommend the best course of action.
Not all diseased trees need to be removed, but if the tree is dead, removal is the safest option. Tree removal is a complex task that requires expert skill to prevent significant damage to property or injury.
Saving a Diseased Tree
As with any illness, prevention is better than cure, and a healthy tree is naturally more resistant to disease. To maintain the health of your trees, follow these simple steps:
- Refrain from applying weed fertilizers near the tree's roots, especially on the grass surrounding it.
- If you're mulching around the tree, ensure there’s a gap around the trunk to allow the tree to breathe and prevent rotting of the wood.
- For trees with exposed roots, prevent damage by trimming manually in that area rather than using a lawn mower or any sharp tool.
- During dry spells, watering trees is crucial as their roots tend to shift upwards in search of water, which can harm their root structure.
- Proper pruning is essential, as incorrect cuts may make the tree vulnerable to disease. Different tree species require specific pruning methods, so it’s best to consult a local nursery or tree expert for advice on maintaining a healthy tree.
Failing to care for your trees can have serious consequences. Some tree diseases have been so destructive that they’ve led to the extinction of entire species. For example, Dutch Elm Disease (DED) nearly wiped out the American Elm population. DED is a fungus that blocks the vascular system, which trees use to transport water.
Elm bark beetles also contribute to the spread of DED. They are drawn to diseased trees to complete their breeding cycle. As the larvae mature into adults, they consume the DED spores and transmit the disease to other trees as they move on.
Once one tree becomes infected, the disease quickly spreads through interconnected root systems, causing the death of nearby trees. A lack of water causes the crown to die, leading to the tree’s eventual wilting and death.
For further details on how to protect your trees, check out the next page for more information.
A tree in good health possesses a remarkable ability to adapt and endure, built to survive even the harshest conditions. Trees are living, breathing entities, and just like humans, they can fall ill or die. Tree diseases can bring down even the most resilient oak or redwood, but many trees fight back, much like a person battling a serious illness. It’s rare to find a tree completely free of disease, as countless microscopic organisms inhabit the tree's bark and roots. Despite this, trees are resilient and typically manage to coexist with these pathogens.
