If landscape plants are not maintained properly, excessively dry soils can cause roots to die, reducing plants’ capacities to absorb water, even after sufficient water becomes available. To replace lost roots, precious energy reserves must be used, which decreases the stored food that affects subsequent growth in the following year.
Drought affects plants in various ways. Besides reducing growth, symptoms can include marginal leaf scorch, wilting, tip dieback, premature leaf drop, chlorosis, and, if severe enough, plant death. Plants that are subjected to water stress drastically decrease their resistance to opportunistic pathogens, such as Cytospora. Bark beetles, borers, and other insects infest stressed trees more easily than healthy, vigorously growing trees.
Plants vary in their ability to tolerate drought. Plants that are well-established and adapted to their site are less affected unless the drought is unusually severe. Since root systems of established plants are wide-spreading and deep, it is vital that enough moisture be applied to reach them. Established trees and shrubs should be watered deeply every 10 to 14 days during dry periods.