Garden Column for the Salisbury Post
Darrell Blackwelder
August 22, 2002

    As I travel through Rowan County, I have noticed quite a few trees under stress are dropping leaves from this seemly unending drought. Four years of drought conditions has taken its toll on many species trees throughout Rowan County. Some of the trees, especially red oaks and dogwoods are beginning to die.
During normal times, trees that drop their leaves early during hot, dry weather will recover. However, these are not normal times and with four years of drought in a row, trees have been repeatedly stressed to a point where recovery may be impossible. Yellow poplar, blackgum, sourwood and river birch are now showing pre-mature fall color and prematurely dropping leaves
    According to tree specialists, if the tree has lost leaves early at least twice in the last three years, then it's probably will not survive another leaf drop. No amount of rain or watering will likely save trees under this much stress. If this is the first year that it has lost its leaves, there is a good chance it will grow new roots and leaves and recover next spring.
    As the water table drops and deep soil moisture is depleted smaller feeder roots responsible for most of the tree's water uptake die. Well drained, sandy soils tend to dry out the quickest and toughest for large tree survival. Trees located on high rock formations also seem to also succumb to drought conditions from lack of root expansion.
Without sufficient moisture, the tree cannot transpire causing the tree to shut down its' biological processes. Unable to transpire, the leaves literally cook in the extreme summer heat. Large leafed tree species such as maple and oaks are often scorched from excessive heat and dry, windy conditions.
    Pines and red cedar are generally more drought and heat- tolerant than hardwoods due to the physical characteristics their needles. Pine trees retain their needles for two to three years during normal times. When stressed, pine trees shed their older needles first, leaving the new growth needles at the tips of branches. As with hardwoods, a pine tree will likely recover if this is the first year that it has shed its needles prematurely.
    Homeowners can relieve some drought stress on trees by removing grass and weeds from around the base and replacing with three or more inches of quality mulch. Grass and weeds compete with young trees for moisture and nutrients. Fruit trees such as peach and apple are stunted from lack bud growth. When competition is eliminated, the tree's roots become more evenly distributed and root volume increases. Larger root mass enables the tree to better utilize what water is available.
    Supplemental irrigation may help if water resources are available. Increasing local water restrictions and those with weak wells may not have this option. Apply water in a donut shaped pattern starting three to five feet from the base of medium to large trees to about five feet beyond the drip line of the tree. Let the water flow slowly into this area for several hours. A long, once-a-week watering is considered more beneficial and a more efficient use of water than several short periods of irrigation during the week. Drip hoses work best in providing an even flow and do not waste water. It is possible to over water some species, such as dogwoods and some oak species. Too much water can force oxygen out of the root zone and result in root kill. If a choice has to be made between watering a lawn and a shade tree, it is best to remember that a lawn can be re-established in one season while a beautiful shade tree may require decades to replace.