Leaf scorch occurs whenever water needed for growth and health of plant foliage is lost from leaves faster than it can be replaced from soil. Any factor that interferes with uptake or movement of water through plants cause water deficiency in leaves. While symptoms are often due to unfavorable environmental conditions, leaf scorch can also result from fungal or bacterial disease.
Leaf scorch symptoms may occur on one branch, one side of a plant, or over an entire plant. Premature defoliation may occur, and small twigs or branches may die back when exposed to water stress or drought. Upper branches often exhibit the most prominent symptoms. Leaves of deciduous plants may initially turn yellow and develop a scorched appearance between leaf veins or along the margins (Figure 1). Needles of evergreens first turn brown at the tips, and over time, the brown coloration progresses towards bases of needles (Figure 2).
Broadleaf and needled evergreens may also be subject to a condition known as winter drying, which produces symptoms similar to leaf scorch. Affected leaves dry out and turn brown along margins or at tips (Figure 3). The plant may develop an overall wilted appearance. Winter drying may also lead to dieback of twigs. Symptoms may not become apparent until late winter or early spring.
For more information on leaf scorch and winter drying of woody plants and related disease problems, review the publication Leaf Scorch and Winter Drying of Woody Plants.
By Kimberly Leonberger, Plant Pathology Extension Associate, and Nicole Gauthier, Plant Pathology Extension Specialist