Leaf scorch
Not an infection: leaves lose water faster than the roots can replace it, so the edges dry out and die
| Type | Not an infection |
|---|---|
| Cause | Not an infection: leaves lose water faster than the roots can replace it, so the edges dry out and die |
About
Brown, crispy leaf edges and tips on trees and shrubs after hot, dry, windy weather. Scorch alone rarely kills a healthy tree, but it is a sign the roots are struggling to keep up.
Also called leaf scorch, scorch, environmental leaf scorch, marginal leaf scorch, dry air, needle tip browning
How to recognize it
Symptoms
Leaf edges and the tissue between veins turn yellow, then brown and dry; in a bad spell they brown without yellowing first, and whole leaves may curl and wither. The side facing wind, strong sun or reflected heat from pavement and walls is usually worst. On evergreen needles, browning starts at the tip and moves toward the base.
Often confused with
Bacterial leaf scorch and wilt diseases such as Verticillium and oak wilt also brown leaf edges; rule those out before blaming the weather or site. Winter burn on evergreens is the winter form of the same water loss (see Winter injury).
Worse when
Temperatures above about 90°F, hot drying winds, drought, low humidity, and a sunny, windy spell right after cool cloudy weather; also roots hurt by construction, transplanting, compaction, pavement, girdling roots, poor drainage or salt.
How it spreads
It does not spread from plant to plant.
When
Mostly July and August; evergreens can also scorch in winter when the ground is frozen.
What to do, gentlest first
This is not an infection, so sprays for diseases won't help. Fix the cause below.
Deep, slow watering in dry spells Prevent
Give trees and shrubs a slow, deep soak during long dry periods, and watch new plantings and trees with damaged roots closely.
Once a leaf has scorched, that tissue will not recover; watering protects the leaves that are still green.
Mulch and protect the roots Prevent
Spread 3 to 4 inches of wood chips, bark or leaf mold over the root zone and water through it. Avoid digging, grading and driving over roots.
Feed only in early spring or late fall, and only as a soil test calls for; skip summer fertilizer and extra nitrogen.
Right plant, right spot Prevent
Give scorch-prone plants like Japanese maples and dogwoods some afternoon shade and wind shelter, and avoid hot spots next to pavement or south and west walls.
Wind and sun screens Barrier
Burlap windscreens or lath shades can shelter tender, valuable plants during hot, windy weather.
Plants it affects
Azalea, Colorado blue spruce, Eastern white pine, Flowering dogwood, Japanese maple, Japanese pieris, Kousa dogwood, Mountain laurel, Red maple, Rhododendron, Southern magnolia, Sugar maple
Sources
Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.