How to Tell If Your Tree Is Diseased

Introduction

Tree diseases can spread quickly if not addressed early. Identifying the signs of disease allows homeowners to save trees before the problem becomes severe. Oregon’s climate supports a wide range of fungal, bacterial, and environmental issues.

Common Disease Symptoms

1. Leaf Discoloration

Yellowing, browning, or blotchy leaves often indicate disease or nutrient deficiency.

2. Early Leaf Drop

Premature shedding suggests stress or infection.

3. Cankers & Sunken Bark

These lesions are a hallmark of fungal infection.

4. Wilting or Curling Leaves

This can signal vascular disease or root damage.

5. Fungal Growth

Mushrooms or conks indicate internal decay.

6. Stunted Growth

Diseased trees often have small leaves, short shoots, and poor vigor.

Diagnosis Requires Expertise

Many diseases appear similar to non-disease stress. For example:

• Drought can mimic leaf scorch
  
  

• Soil compaction can mimic nutrient deficiency
  
  

• Root rot can mimic storm stress
  
  

Certified arborists use tools, sampling, and visual indicators to diagnose issues accurately.