The Effects of Drought on Your Trees

Drought can affect your trees in many different ways. The longer the drought, the more severe the effects on your trees. The effects of drought are considered short-term or long-term, and your trees are more likely to recover from short-term effects.

Short-Term Effects

• Temporary Wilting. As the amount of moisture available in the soil decreases, the leaves on the tree dry out and begin to wilt. The amount of visible tree leaf wilting varies by tree species as well as the amount of soil moisture available. Temporary leaf wilting is usually resolved at night when the leaves are re-hydrated with dew and recover until the next day.

• Leaf Shedding and Coloration. Premature shedding of tree leaves and leaf coloration can be brought on by periods of drought. In many species, leaf mottling or partial browning occurs during droughts. It is quite common for yellow poplar trees to shed leaves during summer droughts, as well as sycamore and buckeye trees. Dogwood leaves wilt and die, rather than being shed during droughts. Summer droughts often cause early autumn leaf coloration, and the needles of conifers may turn yellow and brown.

• Growth Inhibition. Periods of drought decrease the seasonal growth potential of your trees. Drought affects the development of the tree shoots, the width of the annual growth ring in the tree trunk, and the root system. The young roots, which are the major water-absorbers, are the most easily damaged by drought.

Long Term Effects

• Signs of Die Back and Decline. If there is not enough moisture in the soil for an extended period, the roots cannot supply the crown of the tree with enough nutrients and moisture. The result is the crown beginning to die back in order to bring the tree and the root system into a better balance. Leaves, twigs and branches will begin to die, especially in the uppermost areas of the tree.

• Pest Problems. As trees' health decline from long-term drought, they become predisposed to pest attack and infestation. Many pests are unable to survive in healthy trees. However when trees have been deprived of moisture and nutrients for a lengthy period, their response to pest attack is weakened and they have poorer recovery from pest damage.

• Wounds and Disease. Long-term drought weakens the tree's ability to recover from minor wounds, and increases the chances of tree diseases. When a tree is unable to compartmentalize or isolate a small wound, pathogens readily invade and colonize, causing increasing damage. Stem canker disease is a common effect of long drought periods.