Leaf Scorch of Shade Trees

Dr. John F. Baniecki
WVU Extension Service
Plant Pathology and
Entomology Specialist
August 2000

A common disease of many shade trees that may result in premature defoliation is leaf scorch. This disease usually appears during periods of high temperatures, brilliant sunshine, and drying winds that follow a period of rainy weather.

Leaf scorch is due to the failure of the tree roots to furnish sufficient water during this period of rapid transpiration. The lack of water may be due to root injury from paving or construction work, poor soil, or drought. There are also indications that trees deficient in potash may transpire more rapidly than normal and suffer from leaf scorch even though the root system is in a normal condition.

Symptoms

Leaf scorch first appears as a browning of the leaf margins with a rolling or cupping of the leaf. In severe cases, the whole leaf area may become brown and appear scorched. This condition may turn the whole tree brown, or it may appear on single branches, usually more pronounced on the side of the tree exposed to prevailing winds or to the sun.

Control

The most important factor in controlling leaf scorch is to keep trees in vigorous conditions so that root development is adequate to supply sufficient water to the top. If drought conditions prevail, then soil soaking will reduce the severity of the disease. A fertilizer that will give an adequate supply of potash to the tree should be used to guard against a deficiency of potash.

Where root injuries are the cause of leaf scorching, judicious pruning of the tree will help establish a balance between the root system and the top and will thereby reduce scorch injury.