Gardening

Have you ever heard a tree scream? They would if they could whenever a line trimmer comes near. Used improperly, these machines can cause the early demise of trees due to the damage infected to trunks over time.

Photo Credit: William M. Johnson

Proper care can prevent early demise of trees & shrubs

By Dr. William M. Johnson, Galveston County Extension Agent - Horticulture

October 24, 2007

So, if you've had a plant or two to bite the dust a bit soon, at least know that you're in good company. Plants die on everyone, from the professional horticulturist to the novice gardener. Regardless of the care we may give some plants, they just may not survive. And there may not have been anything you could have done to prevent it.

The premature demise of a tree or shrub can be the result of a single factor or from a variety of causes. Some factors such as trunk damage may be readily determined, while others may not. If you plant a large number of plants, expect a few to never become well-established. For example, if you are planting a lengthy hedge of shrubs, it is common to have one or two to never do well. In many instances, it's likely that there is probably nothing you could have done to prevent it.

Death by natural causes is not uncommon. Just expect a certain amount of this after plants are transplanted, and again as plants near the end of the average life span for their species. As a plant reach full maturity, its growth rate slows and its susceptibility to insect, disease and stress problems begins to increase. These are problems that are difficult to avoid, as nature takes its toll. The good news is that many problems and situations that are harmful to plant health are avoidable. These include the following:

- Poorly adapted plants. Plants that like aacid soils, such as dogwood, won't tolerate our highly alkaline gumbo soils. Plants that require cool nights, such as blue spruce, will not do well here. Expect such plants to grow poorly in most Galveston-area landscapes unless you're committed to doing some intensive—and ongoing—soil modifications. In the case of blue spruce, you will also need to provide air conditioning to the landscape!

Do not waste your time and money on plants that are not well-adapted to our area when selecting trees and shrubs that provide the foundation of a landscape design. It's much smarter to depend on plants known to be well-adapted to our growing conditions.

- Transplanting at the wrong time. While wee can buy and plant container-grown nursery stock virtually year-round, we should only dig up and move established plants between mid-November and early February when the plants are dormant. If you do it at other times during the year, expect greater difficulties especially with large-sized specimens.

- Placing excessive fill soil over feeder rroots. Adding more than two inches of soil over the feeder roots of trees growing in our tight clay soils will often suffocate and kill established trees in two or three years. I frequently see this condition following new home construction or after raising the existing soil level underneath the dripline of trees. Even the repeated movement of heavy equipment under and around certain trees on the construction site can prove to be fatal due to compacted soil with resulting root damage.

- Too much fertilizer. Over-fertilization bby overzealous gardeners can deal a fatal blow to landscape plants. Use fertilizer with care and caution, especially during hot weather, and always read and follow directions on the bag or box. Never add granular-type fertilizer to the planting hole when transplanting as such fertilizer can cause root burn.

- Failure to mulch. Research indicates mulcching does more to help new plants establish themselves than any other single factor. A heavy mulch applied around newly planted or established trees and shrubs will work wonders and help to ensure survival and improved growth. What to use? Shredded pine bark, dried grass clippings, pine needles, compost, straw, and hay are good mulches.

- Misuse of flexible line trimmers and lawnn mowers. Whether you know them as weed eaters, weed wackers, lawn trimmers or line trimmers, when used improperly, these machines can lead to the early demise of trees and shrubs due to the damage infected to trunks over time. A weakening and eventual death of a tree or shrub will occur if a section of bark is removed or damaged completely around the trunk (called girdling) by the beating action from line trimmers or the scraping of bark by lawn mowers. The tree may die the same year it is girdled, but I have seen many instances where heavily girdled trees continue to cling onto life for one or even two years and then fail to leaf out the third year.