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Identifying Hazardous Trees. Robert Bardon, Ph.D., RF., Cert. F. Extension Forestry Specialist North Carolina Cooperative Extension Service NORTH CAROLINA STATE UNIVERSITY. What is a hazard tree? has a structural defect that may cause the tree or a portion of the tree to fall.
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Identifying Hazardous Trees Robert Bardon, Ph.D., RF., Cert. F. Extension Forestry Specialist North Carolina Cooperative Extension Service NORTH CAROLINA STATE UNIVERSITY
What is a hazard tree? has a structural defect that may cause the tree or a portion of the tree to fall has a “target” with in the falling distance of the tree or portion of the tree targets include people, vehicles, homes, or other structures Recognizing tree hazards
Looking for hazardous conditions • Inspect systematically • crown • trunk • root zone
Examine the top and crown • Which species of tree is it? • What’s the tree’s history? • Is the tree dead or dying? • Are there dead limbs? • Do some branches cross or rub? • How vigorous is the Tree?
Tree species • Some trees are more brittle than others • bradford pear, willow, silver maple • check with city to see if ordinance prohibits any species • plant brittle species only in open area • avoid locating play areas and patios beneath these trees
Tree history • Past events warn of potential trouble • previous topped trees or storm-damaged limbs result in weak regrowth • unexplained loss of large limbs may be sign of internal damage
Dead and dying trees • should be removed promptly • extremely dangerous to remove • use an expert
Dead Limbs • accident waiting to happen • widow maker • may fall on calm days or if tree bumped • larger than 1” diameter require prompt action
Crossed or rubbing branches • lead to weak spots • opening for pest and pathogens • remove as soon as spotted
Tree vigor • compare to other trees of like size and location • look at • amount of leaf cover • leaf size • leaf color • leaf condition
Check the trunk • watch for forked trunks • sign of potential weakness • cable or braces are used in larger trees to strengthen the fork • prone to infection • early pruning can prevent problems
Inspecting the trunk • what about balance? • removing all the crown from one side of a tree may cause the tree to be off balanced • leaning trees are more of a hazard than those growing vertically • any sudden lean indicates breakage or weakening of support roots and should be remove immediately
Inspecting the trunk • look for signs of decay • signs of internal decay • cavities, disfigurations (cankers), fungal fruiting bodies (conks)
Inspecting the trunk • cavity trees relatively safe Danger Figure based on research by US Forest Service on pine from Tree City USA Bulletin No. 15. Ed. James R. Fazio. National Arbor Day Foundation, Nebraska City, NE. 8 pp.
Inspecting the trunk • wounds and cracks • opening for decay • examine regularly • two vertical cracks appearing on opposite side of trunk • sign of root injury or breakage
Don’t forget the roots • root decay • difficult to detect • major cause • construction • trenching • look for • mushrooms on or near the base of the tree • sudden shift of tree or large cracks in the ground