Apple Tree Leaves Curling Up – Causes and Solutions

Apple trees are a popular and tasty addition to many home gardens. However homeowners may notice the leaves on their apple trees curling up at times. Curled leaves are the tree’s way of signaling that something is wrong and requires attention. Read on to learn the most common causes of apple tree leaf curl and what you can do to restore your tree’s health.

What Causes Apple Tree Leaves to Curl Up?

There are a few key culprits that can lead to curled leaves on apple trees:

Fungal Diseases

Two of the most common fungal infections are powdery mildew and apple scab. Powdery mildew appears as white powdery spots on the leaves. It causes leaves to shrivel and curl up. Apple scab occurs after wet weather and creates yellow, dark spots and blotches on leaves. It also leads to twisted, curled leaves that can turn yellow and drop early.

To treat, prune out affected branches and spray with a copper-based fungicide. Improve air circulation and avoid excessive moisture to help prevent fungal diseases.

Pests

Common apple tree pests like aphids, leafrollers and leafhoppers can cause curled leaves. Aphids leave a sticky residue while chewing on leaves. Leafrollers roll leaves up and feed inside. Leafhoppers feed on the undersides of leaves.

Check for pests on the undersides of leaves. Knock them off with a strong hose spray or use insecticidal soap. Encourage beneficial insects like ladybugs that feed on pests.

Other Factors

Other issues like nutrient deficiencies, over/under watering, damaged roots, and cold weather can contribute to leaf curl as well. Ensure the tree gets 1-2 inches of water weekly and fertilize in early spring. Protect roots from damage. Insulate young trees in cold months.

Signs of Apple Tree Leaf Curl

A few symptoms will alert you to leaf curl issues:

• Leaves rolling or curling inward, appearing cupped or tube-like
• Leaves turning yellow, shriveling, and dropping
• White powdery coating on leaves (powdery mildew)
• Olive green, yellow, or dark velvety spots on leaves (apple scab)
• Sticky residue on leaves from pests like aphids
• Visible pests like aphids, leafhoppers, leafrollers on undersides of leaves
• Distorted, twisted, wrinkled leaves

When Do Apple Trees Get Leaf Curl?

Leaf curl can occur any time during the growing season when the tree is actively producing leaves and conditions are right for pests or diseases. However, curling issues are most common:

• In early spring when cool, wet weather fosters fungal growth.
• In summer when leaves are tender and pests are most active.
• In fall when leaves are maturing and more prone to stresses.

Be extra vigilant about monitoring for pests and diseases during these high risk times.

Effects of Leaf Curl on Apple Trees

If left untreated, leaf curl can weaken apple trees over time. When many leaves are lost, the tree cannot produce enough energy through photosynthesis. This makes the tree more vulnerable to health problems.

Extensive leaf curling year after year can:

• Stunt growth
• Reduce flowering and fruit production
• Weaken branches and increase risk of dieback
• Slow energy storage for winter dormancy
• Increase susceptibility to other diseases

While apple trees can tolerate some leaf loss, recurring heavy damage takes a toll. So it’s important to identify and resolve curling issues promptly.

How to Fix Apple Tree Leaf Curl

The key is identifying the cause and using appropriate treatments:

For fungal diseases:

• Improve air flow with proper pruning and spacing.
• Remove and destroy fallen leaves and fruit.
• Apply copper fungicide sprays at first sign.

For pest infestations:

• Knock off pests with a strong water spray.
• Apply insecticidal soap or horticultural oil sprays.
• Encourage beneficial insects like ladybugs.

For other issues:

• Water thoroughly during dry periods.
• Apply balanced fertilizer in early spring.
• Mulch around tree to protect roots.
• Wrap trunks of young trees over winter.

Ongoing prevention is also important:

• Plant disease-resistant varieties.
• Maintain 2-4 inches of organic mulch around trees.
• Prune annually for good structure and air flow.
• Water deeply and evenly.
• Fertilize each spring.

With prompt treatment at the first signs of leaf curl, you can get your apple tree back to health. But prevention is ideal to avoid curled leaves altogether. Keeping trees vigorously growing through proper care makes them less susceptible to the pests and diseases that cause leaf curling.

When to Seek Professional Help

Most cases of leaf curl can be managed at home with consistent monitoring and care. However, if you notice:

• Rapid leaf loss
• Expanding dieback in branches
• Oozing cankers on bark
• Premature yellowing/browning of leaves

Your tree may have a more serious condition like a bacterial infection. Seek advice from a professional arborist when symptoms seem severe or you’ve had little success improving curl symptoms on your own. A tree specialist can test, diagnose, and prescribe appropriate treatments.

FAQs About Apple Tree Leaf Curl

Here are answers to some common questions about curled apple tree leaves:

Why are my apple tree leaves curling in spring?

Spring weather promotes fungal diseases like apple scab that cause leaf curling. Also, young leaves are more vulnerable to infections and pests. Monitor closely and be ready to spray at the first sign of problems.

What causes apple leaves to curl up in summer?

Summer heat and pests bring on leaf curl issues. Make sure trees are evenly watered during dry periods. Check for aphids, leafhoppers and other insects on the undersides of leaves.

Should I remove curled apple leaves?

Removing a few affected leaves can help reduce disease spread. But extensive leaf loss stresses the tree. Try treating first before removing leaves. Discard diseased leaves in sealed bags, not the compost.

Can too much water cause apple leaf curl?

Excess moisture encourages fungal diseases and root problems that can lead to leaf curling. Let soil dry between waterings.

Why do my apple tree leaves curl then turn brown?

If leaves curl and then turn brown, a fungal infection like apple scab or powdery mildew is likely the cause. Apply a copper spray and remove and destroy fallen leaves to prevent spread.

Are curled apple leaves still good?

Curled, diseased leaves aren’t safe for eating. Remove and destroy them as soon as issues appear to prevent spread. Healthy young leaves are edible, but avoid eating leaves as a rule.

The Bottom Line

Catching apple leaf curl issues early and maintaining prevention practices are key to keeping your apple trees lush and productive. Inspect trees routinely for pests, diseases, and any leaf deformities so you can respond promptly. Provide attentive care through proper watering, fertilizing, pruning, and pest management. With quick response to curled leaves and good ongoing care, you can help your apple trees thrive for seasons to come.