Don't let the boughs break

Like smaller plants, trees also need care and maintenance

In The Garden

July 21, 2002|By Nancy Taylor Robson | Nancy Taylor Robson,Special to the Sun

Drought is not only hard on a garden. It's also tough on trees, whose systems go into survival mode.

"In drought, the stomates [breathing pores] shut down to photosynthesize more slowly," explains Paul Meyers, director of the 100-year-old Morris Arboretum in Chestnut Hill, Pa. While a tree may survive a summer of this, several can kill it.

"Stress is cumulative," he says. "The stress on urban trees, especially, during drought is high because of soil compaction and because so much of the roots are covered by pavement."

Beyond depriving the roots of moisture, hot drought conditions suck water out of the leaves.

In addition to sufficient water, regular maintenance keeps trees healthy and more able to withstand hard times. Armed with good hand tools -- sharp pruners, hand pruning saw and bow saw -- and some basic knowledge, homeowners can do much of it themselves. But keep in mind that each species has its own requirements.

"You need to identify what variety you're dealing with," says Mike Galvin of the Maryland Department of Natural Resources Forest Service

There are excellent references available -- county extension services, Web sites and books. The best show a full-grown specimen and a close-up of leaf, bark and flower as well as a description of characteristics. Given a photograph of the whole tree and sample leaves, county extension services can usually identify trees.

Although trees shed dead limbs periodically, those that die and refuse to come down can be a threat to the health of the tree (and to roof, cars and family). Remove promptly to prevent bark tearing, which exposes the tree to disease and pest invasion. Prune back until you reach live wood, making sure the cut is clean. To take off an entire limb, use a three-cut method. Don't cut it off flush to the trunk; leave a 3/4 -inch stub to minimize the size of the wound. Wound spray is optional.

When to call the expert

When in doubt, call in an expert. Something that looks minor could be major. For example, our 400-year-old buttonwood (American sycamore) developed a potentially lethal spore infestation that looked as though dust from the surrounding farm fields had settled on the leaves -- until it began dropping leaves wholesale. Dosed last fall with Arbotect t, a chemical used to treat Dutch elm disease, among other things, it's come out this summer with a full green canopy and an apparently new lease on life.

"Aphids or scale, which are quite common, can be controlled by insecticidal soap or horticultural oil," says Galvin. "But if you've got an 80-foot maple, most homeowners won't have the equipment to cover the crown to control the insects."

Galvin recommends leaving anything over 15 feet high -- the height of most ladders -- to arborists.

"And never climb a tree, or let anyone else climb it, using spikes," he says. "It's not only dangerous, it opens the bark to infection and rot."

In hiring an arborist, be sure he or she has a state license. Get three bids whenever possible. Prices can vary significantly depending on whether someone will be in the area or have to make a special trip. Get a written contract if possible.

"And never pay 100 percent of the contract price up front," Galvin says. "Make the last payment after the job is finished,"

General maintenance

Watch for wilted leaves as a sign of water stress (and / or disease). The equivalent of an inch of rain a week spread over the root system to the drip line (the outside perimeter of the leaf canopy) will usually bring a tree safely through drought. Water in the early morning or evening with a drip hose or a garden hose left on trickle and moved every hour or two.

Never prune a tree (which is different from taking off dead wood) during extreme heat or drought.

If possible, get a professional arborist to prune limbs that overhang or threaten electrical wires before the electric crews buzz-cut a tree's top, which can expose it to rot. And, for most trees, fertilize in fall.

"When you fertilize in October or November, it lets the tree take it up slowly in spring, which helps build the root system and strengthens the tree," says Joe Unruh, owner of Sharp Lawn and Tree Inc. in Chestertown.

For more information

SOURCES

Maryland Department of Natural Resources Forest Service

580 Taylor Ave. E-1

Annapolis, MD 21491

410-260-8501

Maryland Cooperative Extension (MCE)

There are offices in each county and Baltimore City. For the home and garden information hot line and information on the office in your county, call 800-342-2507

BOOKS

* The National Audubon Field Guide to North American Trees (Eastern Region) by Elbert Luther Little (Turtleback, $19.95)

* Dirr's Hardy Trees & Shrubs: An Illustrated Encyclopedia by Michael Dirr (Timber Press, $69.95)

* Tree Finder: A Manual for the Identification of Trees by Their Leaves by May T. Watts (Nature Study Guild, $3.50)

WEB SITES

www.dnr.state.md.us /

forests /

Has information available, including an online forester, nursery and tree laws

www.dnr.state.md.us /

search.html

Gives a long list of search items including, at the bottom of the page, a list of licensed tree experts

www.agnr.umd.edu /

Has several places to go for drought information and help. Among others, lists extension service publications on forestry and wildlife management including; Leaf Key to Common Trees in Maryland (EB238), $1; Information and Guidance for Forest Stewards (FS 624), free; and Guide to Great Forestry and National Resources Publications (NR91), $7

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