Trees threatened by drought

Most of South
Carolina remains in a moderate to severe drought, and the effects of drought on
trees can be either short or long term.

Short dry
periods might cause wilting, leaf scorch (edges turned brown) and possibly
defoliation in hardwoods or dropping of yellowed needles in pines. Generally,
healthy trees have built-in mechanisms to cope with short-term lack of water.

While
defoliation is a drought survival response to lessen moisture loss, the danger
it presents is reduced photosynthesis. The tree simply cannot produce adequate
amounts of food for present and future needs.

Drought-stressed
trees are also more vulnerable to pests and are less able to compartmentalize
small wounds, making them more susceptible to disease.

Drought
threatens trees by killing the fine feeder roots that collect water and
nutrients. In most trees these are only 12 to 18 inches below the ground’s
surface. As the topsoil dries out the feeder roots begin to die, putting the
root system out of balance with the tree’s foliage. Worse, the tree is rendered
unable to take full advantage of available moisture when rain returns. This
results in branch destruction, especially in the tree’s crown.

Drought
persisting over several years can result in permanent damage or even death. It
is sometimes hard to determine if a tree has died from drought stress or has
just become dormant. When in doubt, allow the tree to stand for another year to
see if it revives.

Homeowners should
consider watering favorite or especially valuable trees to reduce the stress
from drought and heat.

Retired
Extension Service Horticulturist Marty Baker recommended using soaker hoses “in
a donut-shaped pattern starting about five feet from the base of medium to
large trees to about five feet beyond the tree’s dripline.”

Allow the water
to flow for several hours once every week to 10 days when there is no rainfall,
preferably watering in the evening or early morning. Applying a two- to
four-inch layer of organic mulch will help conserve this moisture.