Over Watering is the most common killer of trees. It is important to point out that soil clays do not drain well and have a high capacity for storing water. Plant roots require oxygen, which is lacking in wet soils. Without adequate oxygen, the roots cannot function efficiently and will rot if the soil stays wet for extended periods of time. Keeping the soil too wet or too dry is especially damaging to young trees, but too much water can kill a tree more quickly than too little. Water your trees as needed and not on a fixed schedule.
Adding as little as two inches of soil over a tree’s root zone can lead to death from oxygen deficiency. Almost all of a tree’s feeder roots are in the top twelve inches of soil; the top six to eight inches for some species, such as Oaks and shallow-rooted species are especially susceptible to this type of damage. Placing soil around a tree to make a raised flowerbed is slow but sure way to damage or kill the tree.
Broadleaf weed killers can also kill trees. They should be used with extreme caution, preferably not at all, over the root zone of any tree or other plant that you do not want to kill. The same caution applies to weed-and-feed fertilizers.
When pruning, never leave stubs, which are an invitation to insects and disease. Trouble starts when the stubs begin to rot and the rot moves into larger limbs or the trunk. Always remove a limb back to its point of origin the trunk or other limbs. Cut just outside the bark “collar” at the base of the limb. And remember, there is never any reason to “top” a tree. This practice weakens the tree, destroys its natural shape, leads to weak and unsightly new growth that can break in high winds, and severely shortens the tree’s life.
Many trees, especially young ones, are damaged by the careless use of lawn mowers and weed trimmers. Cutting the through the protective bark and into the cambium layer beneath the bark, interferes with the movement of water and nutrients and seriously weakens the tree. The damaged area also provides entry for insects and diseases.