What every park employee needs to know about young trees.

Whether as part of a ceremony or a routine improvement project, the planting of new trees is a high profile symbol of good stewardship and a plan for a bright future. Tree planting provides both practical and aesthetic benefits and enhances the image of the parks department. In short, it is a practice almost always viewed as money well spent.

But what happens to the park's image when the new trees die or appear sickly after a few years? The disappointment can touch individuals deeply or enrage an entire group such as donors, volunteers who helped with the planting, or officials who authorized the expenditure of funds. It also results in wasted money. In fact, thousands of dollars are wasted each year as planted trees languish instead of maturing and fulfilling their promise. And the blame for dead or sick trees all too often falls on the wrong individuals.

To prevent an unhappy ending to tree planting, here are five basics that should be part of every park employee's training program.

PLANT AT THE RIGHT DEPTH

Tree authority Dr. Alex Shigo states flatly that more urban tree problems can be traced to planting too deeply than to any other single cause. Some planters think they are helping the tree by planting it a couple of inches deeper than it was at the nursery. Others plant on fill dirt that settles under the weight of the tree. Either way, roots suffer. Sucker growth around the base of the trunk, dieback of branches, and lack of vigor are signs that a tree has been planted too deeply. Decline and death come slowly, making it difficult to diagnose planting as the cause of death months or years later.

This is an easy problem to solve. The key is to plant so that the soil level in the planting ball or pot is even with the surface outside the planting hole. To prevent settling the hole should be dug according to the size of the root ball and no deeper. The wall then will sit on firm soil. Soil should not be loosened laterally from the hole to aide the spread of roots.

In poorly drained soils or where turf is irrigated frequently, planting on a slightly raised mound should be considered. As more urban trees drown than die from lack of water, planting at the right depth will help ensure the plant gets sufficient oxygen under both dry and wet conditions.

FREE THE ROOTS AND STOP THE STAKING

Tree experts argue about whether or not it is necessary to remove the material used to hold soil around roots during the move from the nursery to the planting site. The planter should remove as much of the wrapping material as possible once the tree has been set safely in its hole. For wire baskets, the planter should cut and remove as many strands as possible, especially from the upper one-third to one-half of the basket. These simple precautions eliminate the chance of root strangulation and a major cause of circling roots. Instead they open the way for faster root growth and anchorage in the surrounding soil.

As for stakes, these should be used only when absolutely necessary. Usually, this means only conifers and trees on very windy sites. When stakes are unavoidable, rubber or other soft materials should be used around the trunk to avoid abrasions, and a figure-eight loop or guy wires with springs should be employed to allow normal sway. It is believed that natural sway develops stronger trunks and root systems than trees held rigidly in place. Above all, the stakes should be removed after one or two growing seasons to prevent girdling of the trunks or limbs.

PRUNE ONLY TO PREVENT PROBLEMS

Rules of thumb about pruning back newly planted shade trees to provide "balance" with the roots or to reduce wind resistance should be disregarded. Instead, the planter must realize that leaves are food factories that provide the sugars necessary for new root growth. And root growth is what a young tree needs to establish itself on a new site.

What planting a young tree, only dead or damaged branches should be pruned. Corrective pruning or shaping should be done no earlier than the second year and then done only sparingly.

While pruning is important--especially to prevent future problems, it is much easier, cheaper, and safer--for workers and the tree--to prune its branches when they are an inch or less in diameter, rather than putting off pruning until later. Limbs that rub against one another or are too low should be removed, and double tops and narrow crotches should be eliminated. As much leaf surface as possible should be retained. The roots depend on it.

STOP LAWNMOWER BLIGHT

Probably the most common damage to young trees--and the biggest waste of money--is from lawnmowers and weed cutters scraping or cutting bark. Each time this happens, part of a thin, irreplaceable layer of cells is killed. Located just inside the bark, these tissues serve as the tree's vital transportation system, moving water and nourishment to all parts of the tree. Another microscopic layer has the job of providing the only source of new cells that result in diameter growth of the tree. Death of inner bark cells has serious consequences, including breakdown in the tree's chemical defense against fungi that cause decay.

The solution is solely in the hands of those who operate equipment near trees and their supervisors. Training and proper attitudes are essential. A circle of mulch also helps, with the added advantage of reducing competition from grass that has been known to reduce tree growth by as much as 30%.

THINK ROOTS

Roots are a tree's lifeline. Unfortunately, a myth is perpetuated by drawings that show roots as a mirror image of the tree's top, or crown. This would put the roots deep in the earth, safety out of harm's way. This is untrue. Roots usually are found in the top 12 inches of soil, and they spread to distances one to two times the height of the tree. In this "root zone" the tree is vulnerable to trenching for irrigation pipes, excavation for sidewalks, cultivation for planting flowers, and any other disturbance of the soil.

The roots also fall victim to soil compaction. This squeezes shut pores in the soil that are needed for oxygen to reach tiny roots and their helper-fungi (mycorrhizae) that absorb water and essential elements. Finally, the root zone is in constant danger of being doused with chemicals directed at grass and weeds.

Roots must be considered by managers when planning any activity near a tree. The "dripline" should be the minimum area considered absolutely sacred from all soil disturbance. Beyond that zone, care still must be taken. Using fertilizers judiciously, spot-spraying herbicides (if they must be used at all), and aerating annually can counter the effects of compaction. (For more suggestions about working in root zones, write for Trenching & Tunneling Near Trees from the National Arbor Day Foundation, 100 Arbor Avenue, Nebraska City, NE 68410. The cost is $3.)