It is not only you who loves the juicy, crispy, red apple, but also the pests, bacteria, and diseases. Alert! These invaders can suck the sap out of your apple plant and cause curling, browning, and immaturely falling off leaves.
Do you think that’s all about apple tree leaves curling? You are yet to discover the root of their causes, and easy fixes, so buckle up to find out how to grow problem-free apple trees.
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What Causes Apple Tree Leaves to Curl? [Causes & Solutions]
If a few matured and old leaves are curling, you need not make a fuss about it, as it’s a natural process of leaf degeneration.
However, immaturely curled apple tree leaves are not a good sign and could indicate several issues and deficiencies.
So, let’s diagnose the reasons behind apple tree leaves curling to fix the problems effectively.
1. Pest Attack
Apple trees are vulnerable to pests such as aphids, leafhoppers, thrips, and mites. These pests thrive by imbibing on plant sap and laying eggs on leaves which causes curling, bleaching, and falling off leaves.
Aphids- They are small sap-sucking black, green, or white insects that thrive on the leaf’s underside. They leave a brown impression on the leaves and cause them to curl.
Leafhoppers– These greenish or blackish leafhoppers take the life out of your apple tree by sucking the sap out of the leaves.
Thrips– These tiny insects can make colonies on apple tree leaves, compelling them to curl and even fall off.
- Deadhead all the affected parts to prevent further spread and redirect the plant’s energy on growth and developing immunity.
- Immediately isolate your plant from other healthy plants.
- If the infestation is not severe, knock off the pests and their eggs through firm jest of water using a hose.
- Similarly, you can spray the affected parts with neem oil or commercial horticultural oil. You can use a pesticide dispenser or a hose to spray the oil over the plant.
- You can also use 75% diluted isopropyl alcohol on the affected parts to control pest infestation.
- I don’t recommend using pesticides; however, you can use them if the infestation is severe and the flowers have not developed into fruits yet.
2. Apple Plant Disease
Are you familiar with Apple scabs, Powdery mildew, Fire blight, and Sooty mold?
These diseases generally cause bleaching, discoloration, yellowing, browning, blackening, curling, and falling off leaves.
Apple Scab– It is a fungal disease caused by the ascomycete fungus Venturia inaequalis that affects both the leaves and the fruits, causing brown patches along with twisted/curled leaves.
Powdery Mildew– It is a most common plant disease that coats the surface of the leaves with white material and causes deformed leaves that are saucer-like and wavy.
Fire Blight- It is a destructive disease that can cause no fruiting on your apple tree. The leaves appear brown, dry and curled due to their infestation.
Sooty Mold– It’s a fungal infection caused by the secretion of pests such as aphids which leave off white material on the plant leaves or stems.
- Immediately get rid of all the affected parts to prevent further spread.
- Fungicides, especially rich in copper, are ideal solutions for apple scabs and powdery mildew.
- The best way to control sooty molds is to control the pests firsthand. Besides, you can get off this infection by wiping it with soap water.
- Unfortunately, it is hard to cure Fire blight from the tree. The best way to stay away from it is to avoid overhead watering and pruning affected parts.
3. Watering Issues
Generally, fully grown apple trees don’t need watering while growing in a suitable climate where it rains adequately (once every 10 days).
But, if you live in a hot environment, when the soil dries up quickly and does not rain much, you might have to consider watering your apple tree.
Dehydrated apple tree leaves start curling from the tips of the leaves and slowly turn brown.
The problem is associated more with young apple plants with underdeveloped roots, as they cannot properly drain water from the roots.
Similarly, when your apple tree is overwatered, it blocks the oxygen supply to the root, leading to its rot. Overwatered leaves will appear mushy and curled up.
- A rainfall of about 2.5 cm once every week or ten days is ideal for apple trees. However, if your area is experiencing a dry climate without rain, consider watering them once a week or in 10 days.
- While watering, take a soaker hose and run the water for an extended period until the water reaches about a depth of 2 feet, where 90% of the root lies.
- Moreover, avoid overwatering when the soil is saturated.
- Water the plant immediately following the aforementioned technique to fix the underwatering issue.
4. Nutritional Deficiency
Apple trees need a balanced supply of nutrients to yield juicy fruit yearly. A tale-tell sign of nutritional deficiency in an apple tree is the curling of its leaves.
They require a good amount of nitrogen for vegetative growth, phosphorus for root development, and potassium for better fruiting and immunity.
Additionally, it requires other micronutrients to maintain its vitality.
When your apple tree lacks sufficient nutrition, its leaves weaken, curl, turn yellow, and fall off.
- Feed your apple tree with compost once or twice a month or balanced NPK fertilizer (5-5-5) for ideal growth.
- Water the plant before applying fertilizer, as it increases the nutrition absorption rate.
- Always ensure to dilute the fertilizer by 1/4th of its strength as it may burn leaves and roots.
- Also, avoid feeding them during their dormancy in winter.
5. Incorrect Soil PH
Although you supply the right amount of nutrients, it might not be sufficient for your apple. It is because of the hindrance caused by the incorrect soil pH in nutrition absorption.
Soil pH affects minerals and chemicals’ absorption rate.
The lack of nutrients supply in the chain caused by the wrong pH can also be a potential cause for your apple tree leaves curling.
- Always maintain a slightly acidic to neutral pH between 5.8 and 6.5.
- Rainwater is ideal for plants that require acidic soil.
- Mixing pine bark on the soil mixture helps to maintain acidic soil.
- Avoid harsh tap water containing salts as it makes the soil of your apple tree alkaline.
6. Temperature Stress
Apple trees need a slightly cooler temperature, between 40 and 70 degrees Fahrenheit for fruit development and ripening.
Both frost and scorching sun can cause your apple tree leaves to curl.
The scorching sun engulfs water out of the plant leaves rapidly through transpiration. As the leaves become dehydrated, it turns brown and starts to curl.
Similarly, frost can cause water present in the cell to freeze and burn.
It directly impacts the plant’s physiological process, and thus, the plant starts degenerating, the first sign being the curling of the leaves.
- To protect your young apple tree from summer scorch, you can create some artificial shade for young apple trees using some drapes or cloths that block direct sunlight.
- Similarly, increasing the humidity around the plant by sprinkling water over its leaves in the morning can save up water in its leaf to some extent.
- Next, when it snows, you can lay plastic over the area where your apple tree grows and dispose of the snow elsewhere to prevent temperature loss from the soil.
- Similarly, to protect the apple trunk from rodents, you can warp that trunk with plastic up to 3 feet.
7. Transplant Shock
Young apple plants might have some adaptability problems, especially if the environment is unfavorable.
Such sudden environmental changes can cause stress to the plant, which can be seen through its leave curling sign.
Generally, the plant naturally copes with the transplant shock when given the right environment within a few months to a year or so.
However, if you continue to grow them in the same unfavorable environment, the problem will amplify, even killing your apple tree.
The best way to avoid transplant shock in plants is to transfer them during spring or summer and mimic their earlier environment.
If you plan to grow an apple tree from seeds, learn more about process with the complete guide.
Apple tree is not a kind of ‘plant-and-leave’ plant; you need to provide them with the best care to prevent leaf curls.
Proper watering, adequate nutrition, preventing temperature stress, and care against pests and diseases are the best ways to get a healthy apple tree with no problems with leaf curls.