Yellowing and Dropping of Leaves

Unlike leaf spots which are usually scattered at random, this dieback of twigs and yellowing of leaves is caused by roots which are not functioning properly in transporting water to the upper parts of the plant.

Probably the most common problem of ornamental trees and shrubs is a general decline associated with a dieback of twigs and yellowing of leaves. This often begins as a marginal dying on the edges of the leaves or with a bleaching and yellowing of most of the plant. The injured plant often dies.

Possible causes for this problem

Drought stress— this often results in a gradual yellowing of the entire plant, beginning with leaf margins. Even large trees have feeder roots located in the upper portion of the soil and, without adequate moisture, these feeder roots dry out.
Over watering— too much water suffocates the root system and helps disease-producing organisms establish themselves in the plant.
Transplant injury— newly planted ornamental trees and shrubs can be affected by "transplant shock" if roots are damaged before transplanting or if they are subjected to poor soil preparation and poor care at planting time. Soil should be worked up and mulched for several feet around the planting site.
Adapting problem- different plants have different requirements for sunlight and moisture. Selecting a site that is suitable for the plant can avoid many problems. Be sure to select plants adapted to Georgia conditions.
Iron chlorosis- this abnormally yellow color of plant tissues can be observed in parts of the state where soils have a high pH. It's also observed on plants growing near cement walks, driveways and other kinds of construction. Often the soil pH in these areas has been raised by chemicals used in construction.
Fungus root rots and nematodes—these are common pathogens on many ornamental trees and shrubs. The lower stem and roots of several infected plants are rotted and discolored. If the bark is peeled from the plant, you can see dark streaks or fungal strands. Once above-ground symptoms are observed, little can be done to save a plant attacked by root rot organisms. The best control for these rots is to prevent them by maintaining good drainage, fertility and a proper environment for the plant.

For more information on yellowing and dropping of leaves contact your local County Extension Office.