White Spots On Japanese Maple Leaves [4 Causes + Fixing Guide]

White spots on Japanese maple leaves not only spoil the beauty of your tree but can be an early sign of a serious problem. So it is very important to know the cause of such problems on Japanese maple leaves. Several issues play a role in causing white spots on your Japanese maple leaves. But fungal diseases, pest infestation, sunscald, and stressful environment are mainly responsible.

But there is nothing to worry about. In this article, I will elaborate on the issues. At the same time, I will tell you about some simple methods that you can follow to fix your tree easily. So let’s get started.

Quick Caring Guide

Fungal DiseasesA good quality fungicide is recommended. 
Pests InfestationUsing organic can oil is effective. 
SunscaldProtect Maple trees from the afternoon sun.
Environmental StressTake care of your tree regularly

What Causes and Fixes White Spots on Japanese Maple Leaves

1. Fungal Diseases

Several fungal diseases can cause white spots on your Japanese maple leaves. But the most common is powdery mildew. If your plant is in a damp and humid location then this disease is more likely to develop. The disease is easily recognized from the symptoms. Pay close attention to the leaves of your plants. If you notice the presence of something like a white powder in small areas, then it is definitely powdery mildew. Also, the leaves of the plant show some wilting and turn brown after a few days.

Another serious cause of white spots is anthracnose. It is also a fungal disease. Japanese maple trees in very wet and cold locations are more susceptible to this disease. The appearance of white or gray spots on the leaves is the primary symptom of this disease.  Later the tree weakens and may even die.

Fixing Guide

Since powdery mildew and anthracnose are both fungal diseases, their treatment is almost the same. There are basically two ways you can treat fungus-infected plants. One is cultural treatment and the other is chemical treatment. 

If the disease is in the early stages, you can use homemade fungicides. In this case, boil some garlic cloves in a cup of water for half an hour and add baking soda to the mixture. Then mix two spoons from the dishwasher and spray the plant in the morning and afternoon for a week.

If the infestation is severe and cultural treatment fails, you must begin chemical treatment. You can easily rid Japanese maple of powdery mildew by using a good-quality fungicide. Besides, if there is a wound in any part of the plant, it should be cleaned with a potassium permanganate solution.

2. Pests Infestation

If the white spots on your Japanese maple leaves are not caused by a fungus, they are most likely caused by a pest attack. Scales and mealybugs mainly attack maple leaves and are responsible for white spots.

Scales are generally small, flat, and oval-shaped. If you notice carefully you can find them attach to the stems or leaves of plants and feed on their sap. They mainly eat the outermost layer of maple leaves and cause small holes in the leaves. Later, these parts of the leaves are attacked by fungi called pathogens, and white spots are formed.

Mealybugs are small, soft-bodied insects that mainly attack maple trees in damp areas. They feed on plant sap and damage various plant parts including leaves, stems, and roots. While feeding on leaf sap, they secrete a sticky substance called honeydew, which also attracts other insects.  

You’ll always find them on the undersides of leaves and at the base of plants. Their plants have a white waxy protective coating that appears as white spots on the leaves. Mealybugs can weaken plants, stunt their growth, and even kill them if left untreated.

Fixing Guide

For pest control, first, you must identify the type of pest that is affecting your plant. If detected, it should be isolated quickly to prevent other plants from being infected. If the infestation is in the early stages, clean the affected leaves of the plant with a soft brush and try to remove as much scale and mealybug as possible, and prepare the tree for natural treatment.

Neem oil is very effective for early-stage infections. Take a few spoons of neem oil in a bowl and mix it with half a cup of water. Then add a spoonful of vegetable oil and shake it for a while. Spray the mixture on the plant every morning for at least two weeks. Also, to naturally protect your Japanese maple tree from insects, I recommend using natural predators like ladybugs, lacewings, and parasitic wasps in your garden.

To prevent future infestations, you must keep an eye on your Japanese maple for any signs of insects. Make sure to keep your plants healthy by providing them with proper care, such as watering and fertilizing them as needed.

3. Sunscald

Although sunscald is not directly responsible for white spots on Japanese maple leaves, it is indirectly responsible. If your maple tree is exposed to strong sunlight all day and suddenly receives cold weather in the evening, its internal tissues begin to suffer. As a result, problems such as leaf discoloration, leaf fall, and plant weakness occur.

Sunscald can also cause the bark of your Japanese maple tree to weaken and crack.  Later on, the cracked stems are attacked by different types of fungi and insects. As a result, white spots are formed on the stem and leaves of the plant. If the damage is too severe, the tree may lose a lot of leaves and even die.

Fixing Guide

To protect Japanese maple trees from sunscald, you first need to find a perfect location that will receive only morning sunlight. Because Japanese maple trees prefer partially shaded locations. So quickly shift your maple tree out of the full sun, especially if it is a young tree.

Ensure adequate water supply for plants. Dehydrated maple trees are more susceptible to sunscald. In normal weather, watering twice a week is enough. However, during hot periods, the amount of water should be increased three to four times. In this case, I would suggest you apply a layer of mulch at the base of the tree to increase the moisture-holding capacity of the soil.

In addition, the pruning of Japanese maple should not be done untimely. Extra leaves and branches protect the plant from heat, especially in summer when the weather is very hot.

4. Environmental Stress

Sometimes environmental stress also causes white spots on Japanese maple leaves. If your location temperature is too high, the plant’s internal body mechanism may be disrupted and the leaves may turn pale. In addition, excess humidity increases the risk of fungus or insect attack on the tree, white spots may appear on the leaves.

Fixing Guide

Keep your tree under regular care to relieve it from environmental stress. You can keep your maple tree healthy by following rules such as applying sufficient water daily, cleaning the area around the plant, providing shade for the plant, and using insecticides against insect attacks.

Basically, Japanese maple grows well at -10°C. Besides, the hardiness zone should be 6-7. You can also use an automatic humidifier to ensure moderate humidity for plants.

White Spots On Red Maple Leaves

Like Japanese maples, red maples can develop white spots on their leaves. Fungal diseases, bacterial diseases, and insects are mainly responsible for this problem. In this case, the same treatment that applies to Japanese maple trees is also applicable to red maple trees. However, if a bacterial white spot is confirmed, chemical treatment should be arranged as soon as possible.

Frequently Asked Questions (FAQs)

What causes white spots on Japanese maple leaves?

The most common cause of white spots on Japanese maple leaves is a fungal disease called powdery mildew. This disease thrives in humid conditions and can be spread by wind or water. Other possible causes include insect damage, sunburn, or pesticide damage.

Can you spray neem oil directly on the leaves?

Neem oil is an organic insecticide. But in normal conditions, its density is very high so in some cases, the direct application can damage the leaves of the plant. So the best idea is to dilute neem oil with water and apply it to the leaves.

Can white spots on Japanese maple leaves harm the tree?

In most cases, white spots on Japanese maple leaves are more of a cosmetic issue than a threat to the health of the tree. However, if left untreated, powdery mildew can weaken the tree and make it more susceptible to other diseases and pests.

What does the fungus on a maple tree look like?

Maple trees can show different symptoms when attacked by different fungi. However, a fungus-infected maple tree may develop white or gray spots on its leaves, curling leaves, leaf drop, fungal growth on the stem, and a weak-looking stem.

Final Words

Japanese maple trees are mostly affected by various issues when they are young. So after planting, special care should be taken for the tree. Besides, For mature trees, you can solve any issue with regular little maintenance like adequate watering, protection from the sun, timely pruning, and keeping the garden clean.

In case of severe problems, you can fix the tree quickly if you follow the tips I mentioned above. These methods are also applicable to other varieties of maple trees including red maple. 

That’s it for today. Happy Gardening.

James Rivenburg
James Rivenburg
James Rivenburg

James Rivenburg is the founder of plantandpest.com, a passionate gardener with valuable experience and knowledge gained through trial and error. The website has a large community of followers who trust his tips and techniques and have succeeded with his advice. He is always Committed to helping others create a beautiful and healthy garden.

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