Regional Gardening Reports :: National Gardening Association

In the Garden:
September, 2011
Regional Report

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A neighbor is curious about a black oak that toppled across a Philadelphia street and into two houses, thanks to Hurricane Irene.

Will YOUR Tree Topple?

The storm winds are strong; rains are heavy and prolonged. Crack, CRACK, CRASH. Is that your maple tree or the neighbor's ash? A huge branch or the whole tree uprooted?

Is your homeowner's insurance paid up? You've been meaning to call arborist for an evaluation. Is it too late now?

You look out your window. Breathe a sigh of relief. The ash next door has blown down, missing your car. But your neighbor's porch isn't so lucky.

As news of hurricane Irene threatened, homeowners worried about trees falling, branches breaking, people injured, homes damaged. How can we tell if a tree healthy or not? Are there signs we can look for?

YES, says Jason Lubar, ISA Board Certified Master Arborist at the Morris Arboretum of the University of Pennsylvania. Tree health is two-pronged -- biological and structural. Biological refers to cellular activities like photosynthesis, respiration, and growth. Structural refers to the tree's frame.

You can spot signs of a tree in trouble, Lubar explains. If you see any of the problems below, have an arborist come and evaluate the tree's health. Ask the arborist about the potential hazard of large branches dropping or the tree toppling in a storm.

The property owner's first step is to eyeball the tree overall for biological clues, Lubar advises. Look at the leaves: their color and size. Browning and dying leaves indicate something's wrong. Yellow leaves (chlorosis, or lack of chloropyll) could be due to any of an array of nutrient or root problems. Leaves smaller than normal can also signal a tree under stress.

Look at the base of the tree. Are there tree-rooting fungi growing out of the trunk or roots? Don't worry about mushrooms, says Lubar. It's fungi that look like white to brown to lacquer-red shelves that spell trouble. Ephemeral shelf conches (shelf fungi) appear in summer and fall. Woody fungi on the trunk resembles a thick horizontal dinner plate or different-sized plates atop each other. Fleshy fungi, usually found on the roots, can be the size of a large cabbage head, Lubar explains.

Structural signs of possible tree failure include lots of deadwood in the canopy -- large dead branches in the tree that could fall on someone or damage property.

Also, look for crown dieback. Dead ends of branches can indicate a health issue, Lubar advises. It's natural, though, for small dead twigs and branches to drop, he adds.

Cavities -- holes in the trunk -- can create structural weakness. An open cavity at the tree base forming a hole that you can push a stick or an arm into is serious, Lubar says. Less so are squirrel holes and animal holes or decay where a branch has been pruned or dropped off.

Many of us saw trees that Hurricane Irene uprooted. The photo shows a toppled black oak whose root plate split and pushed up the sidewalk. Lubar explains that structural roots at the tree's base support the tree. Healthy, woody, tapering structural roots hold the tree upright. Be aware of them; don't damage them, he urges. "Cutting them when putting in a walkway or pipes could destabilize the root plate."

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