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Introduction
Leaf scorch
is a physiological problem that can occur on any kind of plant. It can be
caused by transplanting, soil compaction, nearby excavation, a nutrient
deficiency, chemical injury, unfavorable weather conditions (such as
drought), poor soil, or limited room for root growth. Scorch often occurs
in July and August, especially on newly planted trees, when the roots
cannot supply enough water to offset the water lost through the leaves in
transpiration. Hot, dry winds will increase the amount and severity of
leaf scorch, especially in the early summer after a cool, wet period.
Symptoms
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Figure
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Symptoms of leaf scorch include yellowing and/or darkening
of tissues between the main leaf veins or along the leaf margins,
sometimes with dark angular spots in the discolored areas. Entire leaves
may be brown and wither when leaf scorch is sever. Plants affected by leaf
scorch may lose many leaves during late summer and exhibit some twig
dieback. However, they often recover if the cause of stress on the plant
is not chronic.
Management
Strategies
Sometimes
severely affected plants may be fertilized and watered to help overcome
leaf scorch. Apply fertilizer in the spring and by broadcasting over the
ground under the spread of the branches at the rate suggested on the label
directions. Proper watering by saturating the soil to a depth of six
inches is especially important. Water once every one to two weeks during
dry periods. Light, general pruning of trees and shrubs helps reduce the
total foliage load that must be supported by the root system. Dead and
dying branches should also be removed. All pruning tools should be
disinfected by dipping them in alcohol or 10% bleach (1 part bleach in 9
parts water) after each cut. Pruning wounds should be coated with shellac
if invasion by canker-causing fungi and bacteria is likely to occur.
If the cause of leaf scorch is chemical injury by salt toxicity,
fertilizer burn, weed killer injury, etc., recovery may be slow. In some
cases, leaf scorch is the first sign of irreparable chemical injury that
may result in the plant's death. If salt toxicity or fertilizer burn are
suspected, where possible leach the soil by slowly trickling water onto
the soil for 24-48 hours. Deicing salt toxicity may be prevented in some
cases by building a curb or drainage ditch that carries the spring snow
melt away from plants' root zones.
Created, KLS, 8/99
This publication contains pesticide recommendations. Changes in
pesticide regulations occur constantly, some materials mentioned may no
longer be available, and some uses may no longer be legal. All pesticides
distributed, sold, and/or applied in New York State must be registered
with the New York State Department of Environmental Conservation (DEC).
Questions concerning the legality and/or registration status for pesticide
use in New York State should be directed to the appropriate Cornell
Cooperative Extension Specialist or your regional DEC office.
READ THE LABEL BEFORE APPLYING ANY PESTICIDE.
__________________________________________________________________________________
The Plant Disease Diagnostic Clinic at Cornell
University is located at 334 Plant Science Building, Ithaca, NY,
14853. Phone: 607-255-7850, Fax: 607-255-4471, Email: kls13@cornell.edu |
