Why are My Oak Trees Dying, and How to Save Them?

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Do you have a grand oak tree in your garden? Then, aren’t you the lucky gardener? Oak trees are signs of ancestry that have resided as a legacy for ages. They are also a symbol of strength that make gardens serene.

But, like everything else, oak trees are on the verge of degradation. You can find oak trees losing their strength and dying with time. The major reason behind such a decline is still unclear.

However, there are various common reasons why oak trees may die with time. Oak trees are prone to several diseases and rot, making them vulnerable. But oak trees are too precious to be lost to such environmental factors.

So if you are also watching your oak trees degrade, you have come to the right place. Here you can find the reasons behind your oak trees dying and how to save them (with pictures) before it is too late. You can adapt the methods and make your oak trees healthy again.

Reasons Behind Oak Trees Dying

Reasons Behind Oak Trees Dying
Image Source: fast-growing-trees.com

As mentioned earlier, diseases and rots are the main reasons behind the decline of oak trees, to name a few, oak leaf blisters, oak wilt, fungal infections, etc. Various environmental factors, such as excess standing water and soil compaction, can also lead to root decay and reduce oxygen levels associated with oak trees.

Moreover, there might be times when lawn mowing may cause injuries to branches, thus making them vulnerable to infections. These reasons can lead to several problems in oak trees, as follows:

1. Armillaria Root Rot

Armillaria Root Rot
Image Source: ucanr.edu

Armillaria root rot is one of the most common diseases that may affect your oak trees. It is caused by a common pathogen named Armillaria. The fungus is quite resistant and survives for years. It mainly resides in dead stumps, dead stumps, and wood debris.

Armillaria root rot starts affecting the root system of oak trees and rises to the lower trunk. A toppling oak tree is most likely to be affected by this fungus. It goes beyond affecting the roots and eventually kills oak trees.

Some signs your oak tree is under the trap of Armillaria root rot are slow growth, yellowed leaves, etc. Moreover, if you find light brown mushrooms at the base of the tree, fungal mats under the bark, and a trunk filled with cankers, you can take them as a sign.

The bad news is oak trees infected with this fungus are difficult to save. They wilt and die most of the time due to the absence of any cure for the disease.

2. Oak Death

Oak Death
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Sudden oak death can also be a reason behind your oak tree dying. It is also a result of a fungus named Phytophthora ramorum. It is considered a waterborne pathogen and makes its way to the bark tissue of oak trees.

It can be a real threat to your garden. It is because this pathogen affects the nearby shrubs surrounding the oak tree, such as camellia, laurel, azalea, etc. This disease mainly affects oak trees in moist and cool environments.

The oak trees suffering from sudden oak death fail to transport nutrients from the leaves. This, in turn, kills the roots and starves the canopy of water. It gives rise to cankers on the bark, spots on the leaves, and discoloration of twigs. Sudden oak death also has no cure, and oak trees die within two years of catching this disease.

3. Oak Wilt Disease

Oak Wilt Disease
Image Source: abilitytrees.com

If you notice your oak tree wilting day by day, it might be under the threat of oak wilt disease. It is also a fungal infection in oak trees, affecting their water-transporting capacity from the roots.

Hence, the rich foliage of oak trees turns brownish and eventually wilts. This disease affects various species of oak trees differently. Some die early, while others keep suffering for years before perishing.

The oak trees belonging to the red oak family, such as scarlet, red, blackjack, etc., take no longer than a few weeks to die. However, the ones belonging to the white oak family, such as swamp white, bur, etc., may live up to several years before dying.

The disease can easily be transmitted by beetles feeding on the sap of the affected trees. Hence, you must consider removing the infected trees to prevent the disease from spreading to other parts of your garden.

4. Hypoxylon Canker

Hypoxylon Canker
Image Source: en.wikipedia.org

Hypoxylon Canker is another disease that might infect your oak trees. It is also a fungus-borne infection caused by Hypoxylon Canker. It affects all species of oak trees and spreads rapidly by spores.

So, it is also a threat to healthy trees nearby. The infection develops dead lesions on various parts of oak trees, such as trunk, limbs, branches, etc. It initiates below the bark of the trees.

The signs of this disease include small, yellow, or brown leaves, stunted twig growth, dead branches, etc. The good part is you can save your oak tree from Hypoxylon Canker if it is affected by less than 15%. Pruning the infected parts of the tree is the only way to save it.

5. Two-Lined Chestnut Borer

Two-Lined Chestnut Borer
Image Source: content.ces.ncsu.edu

Two-lined chestnut borer can also lead to the death of your oak trees. It is an insect that makes its way to the weak oak trees. It affects the nutrient transportation in the trees by forming tunnels on the bark.

The nutrients fail to reach the upper parts of the tree when the tunnels are deep enough to girdle the tree. Hence, the oak trees eventually die starving. If you notice the sudden browning of the leaves, your oak tree might be prey to a two-lined chestnut borer.

Also Read:- 30 Excellent Tree Stump Ideas With Pictures

Methods to Save Oak Trees

Now that you know why your oak trees might be dying, it is time to save them. While some diseases have no cure, you can still save your oak trees from infections and rots. Here are a few methods you can implement to prevent your oak tree from dying.

1. Cut off Infected Branches

Cut off Infected Branches
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Removing the infected branches from the oak trees is the best way to prevent the spread of infection to other parts of the tree or other trees. You will need sharp pruning shears, a saw, and proper protective clothing.

When ready with all the tools and equipment, you need to target the decayed and diseased branches and remove them by pruning. Pruning may also leave trees with open wounds.

It would help if you sealed the wounds with pruning seals or sprays. Once you cut off the infected branches, you must clean the tools with alcohol to remove all traces of infection. It may otherwise infect other trees when used on them.

2. Discard the Dead Branches

Removing the dead, diseased, and decayed branches and leaves from the oak trees is not enough. They must also be removed from your garden and disposed of away from the oak trees to prevent reinfection.

All you need to do is gather the pruned branches and leaves and discard them. You can also burn them in a controlled manner.

3. Apply Fungicides

Apply Fungicides
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Applying fungicides to oak trees is the best way to prevent fungal infections, which they are mainly prone to. You can inject the oak trees with fungicides or spray them on the diseased parts.

You can use anti-fungal sprays for this purpose. It is important to identify the diseased areas of the oak trees and target the fungicides on them. Mixing the anti-fungal sprays in the right amounts and spraying them according to the instructions on the label is necessary.

If the fungal infection goes way too far, using anti-fungal sprays will not be enough. In such cases, you must consider injecting the oak trees with fungicides. Tree injectors help in the process by drilling into the tree. Fungicides help resume the process of water and nutrient transportation in oak trees, thus saving them.

4. Use Fertilizers

After removing the infected parts, you need to ensure the proper growth of the oak trees. To do so, you must fertilize the oak trees with appropriate fertilizer. You can use 10-10-10 fertilizer to help the oak trees heal.

The fertilizers must be mainly applied beneath the branches of the oak trees. You can add fertilizer to the area beneath the tree as wide as it spreads. It helps the trees regain nutrients and retain their functionalities.

5. Practise Mulching

Practise Mulching

Mulching is the best way to ensure perfect root health. Hence, you must apply mulch at the base of the oak trees to prevent root infections. However, leaving a 12-inch space around the tree’s base is necessary.

This prevents moisture trapping in the mulch, which might again infect the roots. Mulching also prevents your lawn from weeds.

6. Allow Proper Water Drainage

As excessive standing water near the oak trees is also a reason behind root rots, you must ensure proper drainage. All you need to do is confirm standing water after watering the oak tree and prepare a proper drainage system if such a case exists.


Now that you know how to save your oak trees, here are a few recommendations to help you prevent them from infections and diseases in the first place.

  • Ensure proper water drainage to prevent oxygen scarcity in the trees during the rainy season.
  • Remove and dispose of the diseased and dead branches and leaves immediately.
  • Ensure proper watering during the dry season.
  • Leave proper space while applying mulch at the tree’s base.
  • Take care while you mow your lawn, so you do not wound the oak trees.
  • Avoid pruning larger branches.
  • Spray fungicides, fertilizers, and insecticides regularly.
  • Apply wound sealant while you prune the oak trees.

Also Read:- 28 Different Types of Palm Trees with Pictures


How does standing water affect oak trees?

Standing water causes root rots and oxygen deficiency. Hence, proper water drainage is essential.

Which diseases affect oak trees mostly?

Diseases such as sudden oak death, oak wilt disease, Hypoxylon Canker, and Armillaria root rot infect oak trees.

How to mulch properly around the oak trees?

You must apply mulch with a 12-inch space at the tree’s base.

Which fertilizer is suitable for oak trees?

10-10-10 fertilizer works best for oak trees.

What if fungal infections have taken a toll on oak trees?

In such a case, you must inject fungicides into the oak trees.


Oak trees are symbols of strength and stand tall as a legacy in many lawns. They live for ages and enhance the beauty of houses and gardens. However, they are also prone to several diseases, which might degrade them with time. Diseases and rots are the most common factors responsible for the death of oak trees. While many come with no cure, identifying the disease at the right time and removing the infected parts can rebirth your oak trees. Hence, you can follow these methods and save your precious oak trees.

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