HAZARD TREE EVALUATION & IDENTIFICATION

***EVERY DEAD TREE IS A HAZARD TREE,

BUT NOT EVERY HAZARD TREE IS DEAD***

What is a target?

Why does it matter?

Does every defect require removal?

How often should you inspect for hazard trees?

Who should inspect for hazard trees?

Why Tree Hazard Inspections are Needed

• Reduce Liability
• Schedule tree work
• Document tree structure/health over time
• Improve tree Health
• Inventory trees

Four main areas to inspect

• Around the base of the tree
• Trunk of the tree
• Main fork area
• Crown of the tree

• Base area 

• Cracked or heaved ground
• Partial uproot
• Fungus growth around base
• Crown Root Rot – Armillaria
• Broken or torn roots
• Broken or heaved sidewalk or asphalt
• Girdled roots
• Base rot or cavity in the trunk
• Recent construction

• Trunk area 

• Cracks or splits
• Bleeding or oozing
• Loose bark covering a cavity
• Fungus growth
• Hollow spots or general decay
• Lightning strikes
• Surface wounds
• Vehicle impacts
• Gauls and cankers

• Main fork area 

• Cavities
• Decay
• Cracks or splits
• Broken leaders
• Large dead sections
• Fungus growth
• In grown supports
• Tight V crotches – Co dominant

• Crown defects 

• Dead limbs or sections
• Broken or hanging limbs
• Topped trees
• Poor tree Architecture

Non-defective tree can create hazardous conditions

• Roots causing pavement heaving
• Branches obscuring signs and street lights
• Trees blocking traffic sight lines
• Branch interference with buildings, utilities, traffic, etc.
• Litter – large fruit
• Thorns on certain trees

Hazard Remedies

• Move the target
• Prune the tree – treat the specific hazard in the tree
• Cable or brace the tree – Limited use
• Remove the tree – Last resort

References and Source Material 

Tree Risk Management, Bruce R. Fraedrich Ph.D. – Bartlett Research Laboratories

Recognizing Tree Hazards, International Society of Arboriculture

Recognizing Living Tree Hazards, Jeff Iles – Dept. of Horticulture, Iowa State University

Minnesota Dept. of Natural Resources and USDA Forest Service, 1996, How to Recognize Hazardous defects in trees.  USDA Forest Service NA-FR-01-96.

The Hazard Tree Web Page – Joseph G. O’Brien, Plant Pathologist, USDA Forest Service

Tree Hazard Inspections, Brian Darr, Southern Forestry Associates, 1999