Japanese Maple Leaves Curling: 13 Reasons Why and How To Treat

Japanese maple trees are known for their beautiful leaves and graceful shape, but they may also show signs of stress through leaf curling.

However, the problem, while troubling to see, doesn’t necessarily mean an end for your tree.

Japanese maple leaves curl due to various factors such as leaf scorch, mites or other pests, fungal diseases, overwatering, underwatering, sudden temperature drops, root damage, and nutrient issues. Each cause requires identification and a specific treatment.

Intrigued about why your Japanese maple leaves are curling? You’re in the right place.

In the following, we’ll delve into the most common causes of this issue, providing a comprehensive guide on how to identify and treat each one.

Whether it’s a pesky pest or a sudden temperature drop, we’ve got you covered. 

Keep reading to discover how you can restore the health and vibrancy of your beloved Japanese maple. Let’s dive in!

Key Takeaways

  • Japanese maple leaves curl due to various factors such as pests, diseases, improper watering, and sudden temperature changes. Each cause requires a specific treatment.
  • Additional factors causing leaf curling include improper pruning, soil pH imbalance, and exposure to wind.
  • Keeping your Japanese maple healthy involves proper planting, appropriate watering, timely pruning, and regular pest and disease control.
  • A dying or green Japanese maple could be due to pests, diseases, improper watering, extreme weather conditions, nutrient deficiencies, or root damage.

There are various problems that can afflict Japanese maple trees. I go over the most common issues in this article 16 Common Japanese Maple Problems: Causes & Easy Solutions.

Japanese Maple Leaves Curling: Causes & Solutions

The curling of Japanese maple leaves can be attributed to a variety of factors. Let’s delve deeper into each cause and explore the corresponding solutions.

1. Leaf Scorch

Leaf scorch typically occurs during hot, dry conditions. It manifests as browning and curling at the edges of the leaves, often giving them a burnt appearance.

Solution: To combat leaf scorch, ensure your Japanese maple receives regular watering during dry periods. Mulching around the base of the tree can also help retain soil moisture and protect the tree from heat stress.

2. Mite Infestation or Other Pests

Mites, aphids, and other pests can cause significant damage to Japanese maples, leading to symptoms such as leaf curling.

Solution: Regular inspection of your tree is crucial for early detection of pest infestations. Depending on the severity, you may need to use appropriate insecticides or introduce natural predators to manage pest populations.

3. Verticillium Wilt or Other Fungal Diseases

Fungal diseases like Verticillium wilt can cause wilting and curling of leaves, often accompanied by a general decline in the tree’s health.

Solution: While fungicides can help treat these diseases, prevention is the best approach. This includes maintaining proper ventilation and sanitation practices and avoiding waterlogged soil, which can create a conducive environment for fungi.

4. Pseudomonas syringae

Pseudomonas syringae is a bacterial disease that can cause leaf curling and cankers on Japanese maples.

Solution: To control this disease, prune infected branches, and apply a copper-based spray like this one. Remember to sanitize your pruning tools to prevent further spread.

5. Aphids

Aphids are small insects that suck sap from the leaves, causing them to curl and distort.

Solution: Insecticidal soap can be effective against aphids. Alternatively, introducing natural predators like ladybugs can help control aphid populations.

6. Overwatering

Overwatering can lead to root rot, a condition that causes leaves to curl and turn yellow.

Solution: Ensure your tree has proper drainage, and water only when the top inch of soil is dry. Overwatering can be just as harmful as underwatering, especially for Japanese maples as they don’t like “wet feet.”

7. Underwatering

Underwatering or drought can lead to dehydration, causing leaf curling and browning.

Solution: Regular watering is essential, especially during dry periods. However, avoid waterlogging the soil as this can lead to other issues like root rot.

8. Sudden Temperature Drop

Japanese maples can be sensitive to sudden drops in temperature, which can cause leaf curling and discoloration.

Solution: Protect your tree with a frost blanket or move potted trees to a sheltered location if possible during sudden temperature drops.

9. Damaged Roots & General Tree Stress

Transplant shock or root damage can cause leaf curling. This is often due to the tree not being handled carefully during transplanting or a disruption to the tree’s growing site.

Solution: Handle trees with care during transplanting, and ensure proper planting depth and conditions. Provide supportive care, such as routine watering and applying a diluted fertilizer, until health is restored.

10. Nutrient Issues

Deficiencies or excesses of certain nutrients can cause leaf curling.

Solution: Regular soil testing can help you understand the nutrient status of your soil. Based on the results, you can apply appropriate fertilizers to maintain a balanced nutrient profile.

11. Improper Pruning

Improper pruning can stress the tree and lead to leaf curling. This is often due to cutting too close to the trunk or pruning at the wrong time of year.

Solution: Prune your Japanese maple during the late fall or winter when the tree is dormant. Always make clean cuts, and avoid leaving stubs.

12. Soil pH Imbalance

Japanese maples prefer slightly acidic soil. If the soil pH is too high (alkaline) or too low (extremely acidic), it can interfere with the tree’s ability to absorb nutrients, leading to leaf curling.

Solution: Regularly test your soil pH, and amend it as necessary. Adding organic matter or specific soil amendments can help adjust the pH.

13. Exposure to Wind

Strong winds can cause physical damage to the leaves, leading to curling. Wind can also dry out the leaves, especially if the tree is not receiving adequate water.

Solution: If possible, plant your Japanese maple in a sheltered location. If your tree is already established, consider installing a windbreak or protective barrier.

Looking up into the canopy of a green Japanese maple.

Tips for Keeping Your Japanese Maple Healthy

Maintaining the health of your Japanese maple goes beyond addressing leaf curling. Here are some general tips to keep your tree thriving:

  1. Proper Planting: Plant your Japanese maple in well-draining soil. The planting hole should be twice as wide as the root ball but no deeper. The top of the root ball should be level with or slightly above the ground surface.
  2. Ideal Location: Choose a location that offers partial shade to protect the tree from the harsh afternoon sun. A sheltered spot can also protect the tree from strong winds.
  3. Watering: Water newly planted trees deeply to establish roots. Once established, water the tree deeply during periods of drought. However, avoid overwatering as this can lead to root rot.
  4. Mulching: Apply a layer of mulch around the base of the tree to conserve moisture and regulate soil temperature. Ensure the mulch is not touching the trunk of the tree to prevent rot.
  5. Fertilization: Japanese maples typically don’t require heavy fertilization. If necessary, a slow-release granular fertilizer can be applied in the spring.
  6. Pruning: Prune the tree during its dormancy period in late fall or winter. Remove dead or diseased branches, and thin out the canopy to allow light and air circulation.
  7. Pest and Disease Control: Regularly inspect your tree for signs of pests or diseases. Early detection and treatment can prevent minor issues from becoming major problems.

Related Questions:

Why Is My Japanese Maple Dying?

Your Japanese maple may be dying due to factors such as pests, diseases, improper watering, extreme weather conditions, nutrient deficiencies, or root damage.

Why Is My Japanese Maple Green?

Some Japanese maple varieties are naturally green. If a typically red variety turns green, it could be due to overexposure to sun or lack of nutrients, but too little sun could also be the culprit.

Final Thoughts

Japanese maples are generally easy to maintain and live for a long time, but problems, such as curling leaves, do occasionally arise.

Now you know exactly what issues may be causing the leaves to curl and how to address the root cause. Good luck!

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