UNIVERSITY PARK, Pa. -- Heavy weather -- thunderstorms, tornadoes and hurricanes -- can exact a brutal toll on trees around homes, but an urban forestry expert in Penn State's College of Agricultural Sciences urges homeowners not to make rash decisions about cutting and pruning trees in the wake of a storm.

"Any big storm brings down trees that break power lines or damage buildings and cars as they fall," says Vincent Cotrone, Penn State Cooperative Extension urban forester based in Luzerne County. "But you don't want to inflict damage on the remaining trees by severely trimming them in a misguided attempt to prevent them from toppling in a future storm.

"Following storms, there usually is a dramatic increase in tree-topping," Cotrone says. "Homeowners believe topping a tree will prevent it from hitting the house in a future storm. In reality, topping and improper pruning will lead to internal decay and a weaker tree."

Cotrone says cutting the central trunk and tops of main branches severely weakens a tree by removing leaves and stored carbohydrates. Topping reduces a tree's ability to generate food and energy by photosynthesis and promotes decay because branches are not removed at their point of attachment, the branch collar.

"Topping usually is done by unqualified and unknowledgeable tree cutters," Cotrone says. "In some cases, arborists top trees at the insistence of homeowners who don't understand that they are paying to have real damage done to their tree."

Cotrone lists several conditions caused by topping trees.

--Unsafe Structure. Topping trees leaves large wounds that are open to decay and insects, ultimately weakening the tree's structure. "The tree also will develop 'water sprouts,' which are weakly attached branches," Cotrone says.

--Decline in Health. In addition to losing the leaves' ability to produce food, topping causes the tree to use valuable food stored in the trunk to regrow limbs. Limb removal causes sunscald of the remaining limbs as well.

Cotrone offers tips on how to clean up toppled or damaged trees in the aftermath of a storm.

--Safety first. Stay clear of any downed power line. Never try to clear tree damage from any power line. "If you have a tree or branch threatening a power line, call the utility company," Cotrone says. "Also, always check trees for broken limbs that may be ready to fall."

--For big jobs, call an arborist. "If the tree is large, and pruning cuts have to be made off the ground, call a qualified arborist," he says. "Do not climb into a damaged tree with a chainsaw or other pruning gear."

--Don't rush into a decision. Cotrone recommends checking the credentials of any arborist. He suggests asking for references, certificates of insurance and whether they are members of professional associations such as the International Society of Arboriculture (which offers arborist certification) or the National Arborist Association.

"After a storm, many people will claim to be a tree specialist," Cotrone warns. "Be patient. If the tree is not an immediate hazard, take your time to find a professional who can explain how to repair damage to your tree or how to remove the tree safely."

Cotrone says homeowners can get information on tree pruning, repairing storm-damaged trees and how to hire a qualified arborist at any Penn State Cooperative Extension office or any Department of Conservation and Natural Resources Bureau of Forestry office.

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EDITORS: For more information, contact Vincent Cotrone at (570) 825-1701.

Contacts: John Wall jtw3@psu.edu 814-863-2719 814-865-1068 fax