Early Leaf Drop of Apple Tree
I have a 15-year-old dwarf golden delicious apple tree. Every year beginning in July it starts dropping it’s leaves. I spray it annually with fungicide and insecticide, but the problem continues. An experienced gardener told me it was the pine trees in my neighbor's yard causing the problem.
Several fungal diseases can cause apple trees to lose their leaves. Apple scab causes olive green or black spots on the leaves. Leaves eventually drop from the tree. Rust causes orange spots on the leaves. The infested leaves will eventually drop from the tree. The alternate host for this tree is the evergreen red cedar (Juniperus virginiana). This may have been the "pine tree" your experienced gardener was talking about. Removal of all red cedars within a mile of the apple will prevent the disease. This is usually not possible since these plants belong to others. Sanitation will help with both diseases. Rake and destroy leaves as they fall to the ground. Fungicides will also help but timing is critical for success. Fungicides must be applied at bud break and every 10 days for a total of 4 to 5 applications. Additional treatments may be needed during wet weather. Do not spray an insecticide during blossom. They will also kill the important pollinating honeybees. As always read and follow label directions carefully.