Holes in Apple Tree Leaves: Identifying the Cause and Solutions

As an apple tree owner noticing holes chewed into your tree’s leaves can be concerning. However, there are several common culprits behind the damage, and solutions to protect your tree. In this comprehensive guide we’ll cover the likely causes of holes in apple leaves and provide tips to resolve the issue.

Common Causes of Holes in Apple Leaves

Here are the most likely suspects eating holes in your apple tree foliage:

• Insects: The main insect pests that feed on apple leaves are caterpillars and beetles. Common leaf-eating caterpillars are tent caterpillars, codling moth larvae, and leafrollers. Beetles like Japanese beetles and weevils will also chew holes.

• Diseases Certain fungal diseases like apple scab frog eye leaf spot and Alternaria can cause dead spots with holes on apple tree leaves.

• Environmental damage: Physical abrasions from wind, hail, or blowing debris can put small holes in leaves. Also herbicide damage can sometimes look similar.

• Wildlife feeding: Deer, rabbits, and other wildlife that nip on apple tree leaves and buds as they browse can leave behind chewed leaves with holes.

Inspect Leaves and Identify the Culprit

To get to the root cause of the damage, closely inspect the leaves showing holes:

• Look for insects like caterpillars on the tree and leaves. Check both top and underside of leaves. Shake branches over paper to dislodge insects.

• Note if the holes have a clean-cut appearance or ragged edges. Ragged holes signal insect chewing. Clean-cut spots indicate disease.

• See if holes occur in clusters or are spread evenly over leaf surface. Clustered damage points to insects while dispersed holes signal disease.

• Consider timing. Are new holes actively forming or is damage static? New holes forming shows an active pest issue vs prior damage.

• Check if holes correspond to known disease symptoms like spots, black velvety undersides, distorted shape, etc.

• Look for other clues like chewed buds, sticky residue, or fecal pellets. Check ground for animal tracks.

Solutions and Treatments

Once you’ve identified the culprit, you can take steps to resolve the issue:

For insect pests:

• Hand pick insects like caterpillars and egg masses. Knock beetles into containers.

• Apply organic insecticides like Bt or spinosad to kill chewing insects. Target undersides of leaves.

• Use pheromone traps and lures to capture pests like codling moth larvae.

• Encourage natural predators like birds and beneficial insects that eat pest insects.

• Use physical barriers like row covers or Tanglefoot to exclude pests. Protect young trees.

For diseases:

• Improve air circulation and prune trees to open canopy and reduce humidity.

• Rake and remove fallen leaves which harbor disease organisms.

• Apply fungicide sprays containing chlorothalonil, myclobutanil, or copper early in the season as preventive.

• Apply sulfur or potassium bicarbonate fungicides to inhibit spore production.

For environmental damage:

• Provide staking, windbreaks, or shelters to protect trees from winds and blowing debris.

• Install hail netting over trees if hail is a recurring problem in your area.

For animal feeding:

• Wrap tree trunks with hardware cloth, metal flashing, or plastic guards to prevent chewing and scraping by deer, rabbits, etc.

• Use deterrent sprays with bitter taste on plant parts to discourage animal browsing. Reapply frequently.

• Install fencing around trees or orchards to physically exclude animal pests.

Preventing Future Leaf Damage

Practicing prevention is ideal to avoid dealing with chewed up apple tree leaves each year:

• Select pest and disease resistant apple varieties better able to tolerate insect and disease issues.

• Maintain tree health and vigor through proper fertilization, watering, pruning, and soil amendment. Healthy trees withstand pests better.

• Clean up dropped fruits and leaves which serve as reservoirs for insect and disease pests.

• Use dormant oil sprays to smother overwintering pests.

• Apply sticky barrier bands around tree trunks to prevent climbing pests.

• Regularly monitor trees for early signs of pest problems. Take action before damage escalates.

• Promote beneficial insects by providing pollen and nectar sources. They prey on bad bugs.

• For young orchards, utilize row covers or netting before pests arrive in spring.

While seeing those unsightly holes in your apple leaves can be disheartening, rest assured the damage is usually only cosmetic. Taking the time to properly identify the cause and apply targeted solutions will help protect your apple trees and keep them growing strong. With quick action, you can outsmart whatever is munching on your tree’s foliage.