The initial burst of spring blooms on apple trees is a delightful sight that guarantees prosperous growth and fresh, crunchy fruit!
Spring and summer conditions can surprise you though (and not always in a good way).
If you’re spotting yellow leaves on your apple tree, unprecedented weather, poor soil, and imbalanced watering could be the culprits.
Here are 8 common causes for yellow leaves on your apple tree, the telltale signs of each issue, and how to fix the problem.
Yellow leaves are not the only issue you may experience with your apple trees. Be sure to read my comprehensive article, Apple Tree Diseases and Pests, to learn more.
1. Watering Issues
Too little watering (along with hot and dry spells) can cause drought stress, inhibiting mineral and nutrient absorption.
Likewise, overwatering your apple tree will lead to waterlogged soil, stressing out the roots to the point they can no longer take nutrients in and up to the leaves.
How To Identify
- Leaves on the bottom branches and inside the crown turn yellow (overwatering).
- Leaves wilt after yellowing before dropping early, along with fruit dropping off prematurely (underwatering).
How To Remedy
- Allow soil to dry between watering. Check that the top 4 inches of soil are dry before watering.
- Use a well-draining and fertile loamy soil medium for balanced moisture levels. Avoid using clay soil as this retains too much water.
- For underwatered trees, conserve moisture by applying 2-3 inches of mulch (bark, straw, etc.) around the base, leaving a gap of at least 3 inches from the trunk.
2. Nutrient Deficiencies
Without the proper proportions of nutrients like iron, nitrogen, and magnesium in the soil, growth will slow and chlorophyll production will be poor, resulting in pale green to yellow rather than lush green leaves.
How To Identify
- Leaf veins remain green, but entire leaves turn yellow before dropping.
- New leaves are smaller, pale green, and slightly deformed (curling).
- New growth can take on a herringbone pattern in cases of magnesium deficiency.
How To Remedy
- Check the soil pH. Even with sufficient nutrients in the soil, imbalanced pH could be throwing things off. Ideal soil pH for apple trees lies between acidic and neutral (5.8-7.0).
- Use an organic fertilizer. This slow-release fertilizer is excellent and won’t burn the roots.
3. Pests
Apple trees attract their share of boring and sap-sucking insects such as aphids, caterpillars, and spider mites.
These pests love to feed on the foliage and bore into the wood, weakening leaf tissue and drawing trees of energy, resulting in pale, discolored leaves.
How To Identify
- A common culprit is the round-headed apple tree borer. Look for ¼-inch round holes in the trunk and reddish-brown frass (sawdust and larvae droppings) on the bark or near the base of the tree.
- Severe pest damage can manifest in sparse foliage growth and branch dieback.
How To Remedy
- Use a natural homemade insecticide spray to prevent contamination of fruit, and apply it generously to the foliage.
- You can also sprinkle diatomaceous earth (containing silica and fossilized aquatic plants) around the base of the tree to kill ground-dwelling bugs and larvae.
- Some treatments can kill beneficial insects and pollinators, so only apply outside of your apple tree’s blooming period.
4. Diseases
Warm and rainy weather can carry fungal spores from one tree to another, infecting and weakening healthy leaf tissue.
Some apple tree varieties can simply be more susceptible to disease than others.
How To Identify
- Bronze-orange or yellow spots on leaves (a sign of cedar apple rust).
- Blotchy yellow spots on leaf edges in summer (commonly identified in Honeycrisp varieties).
- Fruit appears mottled or distorted.
- Symptoms similar to nutrient deficiency (curling leaves, veins remain green while entire leaf turns yellow).
How To Remedy
- Remove damaged foliage and fruit, and apply a broad-spectrum fungicide weekly (I use this one).
- Clear any weeds and debris within a 6-foot radius at the base of your tree to prevent spore transportation.
- Prune 10-20% of the tree in winter to promote better air circulation using sanitized pruning shears or loppers depending on branch thickness.
- Plant disease-resistant varieties.
5. Root Damage
An apple tree’s roots mainly grow shallowly and in an outward lateral form, which can leave them damaged by the sun in extreme heat.
The roots can also be quite susceptible to rot in unusually wet weather spells or when overwatered.
How To Identify
- Less vigorous or slow overall growth.
- Leaves on the lower branches turn yellow with discoloration working its way to the inside of the crown and moving outward.
- Delayed bud break in spring and twig dieback.
How To Remedy
- Plant your tree in a well-drained location (free-draining fertile, loamy soil). If soil is compacted, try amending it with a potting mix rich in sand for a porous quality.
- In times of extreme rainfall, consider digging a ditch around the tree to prevent water from stagnating at the base.
- Apply mulch around the base in spring to protect it from the summer heat.
6. Leaf Senescence
Senescence is part of the natural aging process of trees in which resources are diverted from older or damaged tissue to areas where it is needed most.
Fungal infections caused by poor weather and soil conditions can trigger senescence, but it can also happen when the tree has been fully harvested during the growing season.
How To Identify
- Leaves appear wilted.
- Yellow leaf edges.
- Leaves turn pale green to yellow en masse during summer.
- Bark may be dark/discolored and feel slimy when wet.
How To Remedy
- Maintain balanced watering, and ensure the soil has good drainage (if needed, amend with compost, loam, or sand-rich soil mediums)
- Harvest apple fruit at the appropriate time for your variety (some are ready to pick in August, but others are ready early-mid fall).
7. Excessive Fruit Load
A bountiful apple tree sounds great, but an overproduction of fruit can deplete the tree of nutrients needed elsewhere, such as in the branches, bark, and buds for next year’s growth.
Crowded conditions also mean fruit touching each other, which can risk disease spread due to poor air circulation.
How To Identify
- Trunk or branches appear to bend under the weight. Slimmer branches may break.
- Fruit is smaller than expected.
- Fruit is dropping prematurely.
How To Remedy
- Look for “double” fruit that appears fused together or any deformed fruit, and remove these. To remove fruit, carefully pinch and twist them off using your fingers, or clip them using small pruning shears.
- Thin trees when they’re young as slimmer branches are more prone to breakage. Thin out apple clusters to no more than 1-2 fruits per cluster, leaving the largest apples behind.
- Consider pruning out some of the branches from the overloaded side to balance the weight.
8. Environmental Stress
Sudden weather changes (swings of around 20ºF or more either way) can shock your apple tree’s leaves into yellowing prematurely.
As most apple trees are tolerant to cold, sudden heat stress is more likely to result in yellow foliage.
How To Identify
- Solid yellow leaves.
- Some leaves are dropping prematurely.
How To Remedy
- Apple trees thrive in areas where temperatures rarely rise above 90ºF, so check that the average temperature in your region is conducive to this.
- Applying mulch can help protect and cool the roots, which helps the tree to stay cool overall as happy roots can send sufficient moisture to the leaves, encouraging healthy green growth.
- Additionally, consider providing shade for young trees or moving potted apple trees to a shady spot in your landscape until extreme heat subsides.
Closing Thoughts
Yellow leaves on your apple tree can be caused by things like pest damage and weather extremes but also by improper watering and a lack of nutrients.
Most of the above causes have simple fixes, such as amending your soil quality, applying mulch to the base, or pruning unwanted and unhealthy growth.
Identify these issues quickly, and you’ll be able to enjoy a healthy and prosperous apple tree for many, many years!
If you’re interested in learning more about apple tree problems, check out these articles next:
- Lichen on Apple Trees – Causes, Effects & Control Methods
- Apple Scab: Causes, Impacts, Prevention and Treatment Plan