Every fall, visitors trek to Forest Grove, Mount Hood, the Columbia Gorge, and the Willamette Valley. Oregon’s bright maples, golden oaks, deep red dogwoods, and yellow birch trees are spectacular. However, if leaves start dropping off your tree during the growing season, something’s very wrong.
Diagnosing a tree problem helps you know when to contact Oregon Arborist for the best tree services in Forest Grove, OR. In this blog post, we’ll answer the question, “Why do trees lose their leaves in the summer?” See the potential tree problems listed below.
Drought Conditions Starve Roots
Oregon went through a severe drought for several years leading up to 2025. Even though conditions improved, many trees in Forest Grove are still trying to recover. Without enough water, these trees may start shedding leaves to slow evaporation and protect themselves.
Why do trees lose their leaves in the summer? Drought stress could be your reason.
Heat Stress Triggers Premature Leaf Drop
Heat stress forces the tree to close the pores on the leaves to retain moisture. When those pores stay closed too long, the leaves suffocate and drop off. Heat stress also weakens branches, strips bark, and leaves open wounds that invite pests.
By the time you see thinning leaves, heat stress will have already damaged the internal systems your tree needs to stay healthy. Be on the lookout in hot weather and adjust your watering schedule.
Pest Infestation Devours the Canopy
Pest infestation takes advantage of trees already under stress. Weakened defenses make it easier for beetles, caterpillars, mites, and borers to feed on the leaves and stems. As they destroy the tissues that move water and nutrients, the leaves start falling.
Ignoring pest infestation opens the door to infections that push your tree closer to death. Once they reach the trunk, the damage spreads deeper into the tree, and tree removal might be your only option.
Leaf Scorch Burns Leaves From the Inside Out
Leaf scorch happens when leaves release moisture faster than the roots can pull it in. Characteristic signs of leaf scorch include:
- Leaves dry on the edges.
- Curled leaves.
- Quite bare branches in summer.
Drought, poor soil, and root damage exacerbate the problem, and bare branches are vulnerable to sunburn and decay. Early intervention is best.
Environmental Stressors Stacks Up
When you stack all the environmental stressors, your tree needs defenses against drought, heat stress, leaf scorch, pest infestation, and root damage. Each problem wears the tree down, so don’t ignore the question, “Why do trees lose their leaves in summer?”
When leaves drop during the summertime, your tree faces multiple problems. Leave your tree’s health to chance, and it might not have a way to recover.
Don’t Let Nature Decide Your Tree’s Fate
Each stressor pulls the tree in a different direction and makes the damage worse. If you’re still asking yourself, “Why do trees lose their leaves in the summer?” check out our other blog on evergreen tree leaf loss. Alternatively, contact Oregon Arborist at (503) 899-4166 for the best tree services in Forest Grove, OR.