If you had thousand-dollar bills lying all over your yard, wouldn't you go out and grab as many as possible? The average value for a 10-inch diameter tree is about $2,000. A tree with a 30-inch diameter has an average value of around $15,000. Trees are valuable assets that need to be protected. I see many trees in the Chattanooga area under extreme stress.

The value of trees has a deeper meaning. A house without trees is like a picture without a frame. Houses look bare without several good-size trees around them. Beautiful trees increase the real-estate value of property. The presence of a large shade tree is often a key factor in buying a new home.

Trees grow as the family grows. They become part of the family history. It is extremely difficult to lose cherished living trees. Sometimes, they only need a small drink to survive.

Drought indicators

Drought is a primary contributing factor to tree decline. Trees growing on thin clay soils are more susceptible to drought. Insects and diseases also can strike at certain times of the year. The summer heat puts extra stress on trees.

Construction of buildings, patios, garages, driveways and sidewalks often damages roots of nearby trees. The combined effect on the tree is much worse than a single factor. For instance, large, healthy trees usually can handle occasional defoliation from caterpillars. However, if this situation persists for several growing seasons, the tree may die. Trees are so efficient at storing food reserves. So it may take two or three years after a stress episode before decline appears.

There are several indicators that a tree is suffering from drought. The leaves might be smaller than usual. There may be reduced shoot growth. Over time, this results in the overall stunting of the tree. Damaged or fallen leaves may be evident. Discolored leaves often mean soil or nutritional problems. There is not enough root moisture to carry the nutrients to the leaves. These issues gradually can lead to a weak root system trying to support a top-heavy tree.

Tree roots extend two to four times the height of a tree. Most tree roots are in the top 2 feet of the soil. During a drought, the root system is reduced. If a tree tips in a storm, it often means the tree had damaged or poorly developed roots before the storm pushed it over.

Water can help

Most of the time in Chattanooga, rainfall is sufficient to sustain trees. Most healthy, established trees can make it through periods of moderate dryness. However, summer months usually contain periods of several weeks without any rain. Windy conditions can increase the amount of moisture being lost through the leaf surfaces. My rule of thumb is to water when there has been no water for two weeks and there is no rain in the forecast.

Watering during a drought is expensive, but it may be worth it to save years of investment. A $100 water bill to save a $1,000 tree is good logic.

The best ways to water trees are by soaker hose or trickle (drip) irrigation. Newly planted trees often need weekly attention for the first three years before they are self-sufficient. Evergreen trees may need watering in winter months if there is little rainfall or snow. The best time to water is late at night or early morning.

Remember that overwatering is generally worse than underwatering. Overwatering drowns the tree. The tree needs oxygen to live. So it is best to water only as needed, generally once a week or once every two weeks. Water deeply each time so water soaks into the roots. If water restrictions occur, then rain barrels are important to have. They provide that life-saving drink a tree needs in midsummer heat.

See information on drought-tolerant trees at UT Publications, https://utextension.tennessee.edu/publications/Pages/default.aspx.

Contact Tom Stebbins at 423-855-6113 or tstebbins@utk.edu.