Don't neglect the trees just because it's cool outside

One of the chief paradoxes of fall is that deciduous trees often are ignored at the very time their leaves attract the most attention.

Experts say that autumn is a good time to plant or transplant trees, to mulch them, and also to assess their condition.

"Most people don't realize that even when trees lose their leaves, they're not completely dormant," says Sharon Lilly, technical director of the International Society of Arboriculture (ISA). "The roots are still growing."

"Fall is actually a better time than spring to plant trees and shrubs," says Luann O'Brien, a spokeswoman for SavATree, a tree and shrub care company based in Bedford Hills, N.Y. "The soil condition is better and the stresses are fewer."

Many nurseries have fall specials on trees, Ms. Lilly points out. Getting trees into the ground now, she adds, allows roots to grow before new leaves begin to bud next spring.

Both Lilly and Ms. O'Brien stress the importance of giving trees a good watering this time of year. "You don't want to let trees go into winter dry," Lilly cautions.

The eastern United States, O'Brien notes, has experienced what amounts to a two-year drought, and even a heavy, late-season rainfall isn't viewed as an adequate substitute for a couple of good, long soakings.

If your area has been dry, turn on sprinklers or the irrigation system, she says, and let the water "soak down nice and slow and easy" for several hours.

A quick drink from the hose won't do the job. Tree roots are competing with lawn roots for water and minerals, so it's important that water penetrate the top six inches of soil, where the vast majority of a tree's tiny, moisture-absorbing roots reside.

These cover a large area. To envision it, Lilly suggests, picture a goblet on a dinner plate. The goblet represents the tree, the plate the wide-spreading root system. This illustrates why it's important to spread a wide swatch of mulch around a tree.

"If the tree had its own way," Lilly suggests, "the whole yard would be mulch. Putting a tiny ring of mulch around a big, mature tree doesn't benefit the tree that much."

Mulch helps retain soil moisture. "It [also] serves as an insulating blanket from temperature extremes," Lilly observes, "and if you use a nice organic mulch it's constantly breaking down, which is good for the soil."

When spreading mulch, avoid pyramidal mounds around tree trunks, which can cause rotting. "I prefer organic mulch, three to four inches in depth, and not up against the trunk," she says.

If there are multiple trees and shrubs in the yard, removing the grass around these plants and connecting them with an island of mulch more closely simulates how they grow in nature than does placing them individually in the middle of the lawn with just a tiny ring of mulch around each, Lilly says.

Mulching also keeps lawn mowers and string trimmers at bay. Once the tree's bark is clipped and the trunk wounded, insect infestation may follow.

In raking or blowing leaves, O'Brien advocates not being too meticulous, especially at the end of the season. "You don't want a heavy coverage of leaves because too many will damage the grass, but a reasonable number act as fertilizer for the root system" when they decompose.

In her own yard, she mows rather than rakes, letting the leafy byproduct of mowing fertilize the lawn.

As trees head into winter, SavATree recommends a storm-damage prevention audit, which O'Brien says is simply a walk-through by an arborist who can inspect the trees' structure. Branches that are at risk because they contain dead wood or are under stress can be removed or supported by cable.

This time of year, homeowners may look ahead to winter and worry about their liability if snow should cause tree limbs to fall, resulting in damage. Unfortunately, some tree owners try to lessen the risk by having their deciduous trees topped.

Topping is the practice of cutting back branches so that large stubs are left (instead of pruning branches back to the trunk or a larger branch, which is the correct procedure).

The stubs left by topping often serve as entry points for insects. They also develop vigorous thin stems, called water sprouts, that are unsightly and weaker than normal growth.

Arborists have campaigned against topping for years, but Lilly considers it a nationwide problem despite decades of educational efforts.

"It's mostly a combination of consumer fear - people afraid that their trees are too tall - and uneducated tree-care providers."

Partly to protect consumers from poor workmanship, the ISA, a nonprofit organization based in Champaign, Ill., runs a certification program.

The group's Web site (www.isa-arbor.com) provides a wealth of tree-care tips and tells how to contact certified arborists who've logged at least three years professional experience and passed a comprehensive exam.

(c) Copyright 1999. The Christian Science Publishing Society