Tree owners often feel compelled to spray, prune or apply something to their trees and landscape plants on a regular basis.

But, unless there is a specific reason, the best way to keep your trees healthy would be to apply a layer of mulch.

"Fall is a great time to be out in the yard spreading shovels-full of composted woodchip mulch under your trees." said Tchukki Andersen, staff arborist with the Tree Care Industry Association.

"Trees with mulched root zones are usually larger, more vigorous, develop faster and have higher rates of survival than plants surrounded by turf grass or bare dirt. Mulches retain soil moisture and reduce erosion and soil compaction."

Mulched trees also have fewer weeds, which reduces the need for the roots to compete for limited resources. The soil under the mulch also likely stays warmer longer into the winter and also warms faster in the spring, helping extend the growing season for plants.

Organic mulches are a favorite among professional arborists, who view wood chips as an excellent, attractive mulch for trees. Other organic mulches include bark chips, ground bark, composted lawn clippings, leaves and straw.

• How wide is wide? A good mulch bed should extend out at least three feet from a tree's trunk in all directions, though extending out to the drip line is preferred. This where the fine, absorbing tree roots extend out into the soil, and mulch provides many health-related benefits for those roots.• How deep is deep? The mulch bed depth should be 2 to 4 inches.• Cover the grass. If there is grass in the area that needs mulching, put a five-page layer of newspaper over the grass, get it wet, then add mulch.• Use the right mulch. For poor soils, use well-composted mulch to build up the nutrients. Soils that are healthy will do fine with a highly stable softwood bark such as cypress bark.

• No volcanoes, please. The biggest no-no when mulching is to create a "mulch volcano" that is piled high around the base of the tree. This practice traps moisture around the tree trunk and root flare leading to decay and structural failure.• Avoid fine mulch. Thick blankets of fine mulch can become matted and prevent the penetration of water and air.• Don't let mulch sour. Low oxygen levels from packed-down mulch creates a toxic "sour" mulch, which may give off pungent odors, and even worse, the compounds produced, methanol and acetic acid, can kill young plants.• Don't keep adding new mulch on top of the old. While mulch does decompose, you do not want to accumulate excessive mulch year after year by adding fresh mulch every spring.

A professional arborist can assess your landscape and work with you to determine the best treatment for your trees and shrubs.Contact the Tree Care Industry Association (TCIA), a public and professional resource on trees and arboriculture since 1938. It has more than 2,000 member companies who recognize safety and performance standards and who are required to carry liability insurance.To find a tree care service provider in your area, use the "Locate Your Local TCIA Member Companies" program by calling 1-800-733-2622 or by doing a Zip code search on www.treecaretips.org.The association is at 136 Harvey Rd, Suite 101, Londonderry, NH 03053.