Source:
Ed Gilman egilman@ifas.ufl.edu, 352-392-1831 ext. 373

GAINESVILLE, Fla. — Weeks have passed since Florida rode out the first major storm of an active hurricane season, but falling trees could cause injuries and property damage for weeks or months to come, says a University of Florida urban tree specialist.

“The next month or so is going to be a dangerous period,” said Ed Gilman, a professor of environmental horticulture at UF’s Institute of Food and Agricultural Sciences. “There are trees and branches that have been weakened by storms, and some of them won’t fall for weeks, maybe even longer.”

Since this year’s hurricane season kicked into high gear, Gilman, an expert on placement and pruning of trees in an urban environment, has received a flurry of telephone calls and e-mails from homeowners looking for tips on how to clear trees downed or damaged by storms.

But while storm victims are struggling to clean up downed trees and obviously damaged limbs, Gilman said, some trees may suffer hidden injuries that could send them crashing down long after the storm has passed.

“Leaning trees are at the top of my list for things to watch out for,” Gilman said. “Even if a tree has just a slight lean — ten degrees or so — you need to take a close look at it.”

Trees tilted even slightly by a storm may have sustained root damage that will make them much more likely to fall in the future, he said. And even if a tree isn’t tilted, movement during high winds can dislodge the soil around the roots that give the tree its support.

“If there’s a bulge or disturbance in the soil around the base of a tree, there’s a good chance you’ve got some root damage,” Gilman said.

Some trees, even large ones, can be righted and saved, he said, but homeowners should consult an arborist certified by the International Society of Arboriculture to decide whether a tree should be treated or cut down.

Trees with “co-dominant” trunks — twin or multiple trunks of roughly the same size — are among the most likely to break in a storm, he said. But even if co-dominant trunks don’t break apart, he said, they may develop hairline fractures that lead to later breakages. And sometimes those cracks occur high on the trunk of a tree.

“You should look for fractures in trees with co-dominant trunks, even if it means getting out the binoculars or hiring an arborist to climb the tree,” he said.

Most storm victims clear broken limbs out of their yards soon after the storm passes. But even large broken limbs can remain caught in the canopy of a tree after a storm passes — and can plummet out of the canopy without warning. You should take those branches down before they fall, Gilman said.

“If you see a patch of brown foliage in the canopy, you’ve probably got a broken branch up there,” he said. “Those branches can be hard to spot right after the storm, but if you had damage from Hurricane Frances, you should see them turning brown now.”

A few other tips on dealing with downed or damaged trees:

• When trimming damaged limbs from a tree, remove hanging and damaged limbs first. Cut broken branches back to the nearest major living limb, or all the way to the trunk if necessary.
• Most trees don’t suffer a lack of water in the immediate wake of a hurricane. But like most plants, trees stay healthier if they’re watered during periods of low rainfall. Irrigating damaged trees in coming months can help them recover.
• Some people apply fertilizers to the soil around damaged trees, but Gilman says there’s no evidence this helps them recover. If a tree suffered a nutrient deficiency before the storm, it might see some benefit from fertilizers, he said.
• When a tree loses branches during a storm, it also loses some of its ability to perform photosynthesis. After a storm, damaged trees will often put out sprouts at the tips of broken branches. As these sprouts grow, they will help the tree regain some of its photosynthesis-generating ability. These sprouts should be allowed to grow for several years without pruning.

Now is a good time for homeowners to start thinking about — and landscaping for — the next storm. Some of the tree damage caused by hurricanes Charley and Frances could have been avoided with better landscaping and pruning techniques, Gilman said.

“Particularly in the outer bands of both storms, we’re seeing a lot of tree damage that didn’t have to happen,” he said. “People are paying the price for bad decision-making, or none at all, before the storm.”

Many healthy trees can stand winds of minimal hurricane force, Gilman said. But in urban areas, trees often fell in much lighter winds because their roots were damaged by paving or construction too close to the base of the tree. Other downed trees, he said, could have survived if they had been pruned to reduce their resistance to the wind. And some landowners increased their likelihood of tree damage by planting species that are prone to failure in high winds, such as laurel oaks.

Homeowners can find tips on both pre-storm and post-storm pruning on Gilman’s Web site, http://hort.ifas.ufl.edu/woody/stormprep.htm

Gilman has put the tips to use at his own Gainesville home, where he rode out Hurricane Frances with no major tree damage, despite wind gusts in the area as high as 70 miles per hour.

But even good landscaping can’t save trees at the heart of an intense hurricane, he adds.

“If you’re in an area with winds of say, 120 miles per hour, you can count of plenty of damage no matter how much you’ve prepared,” he said.

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