Insect
and Disease Fact Sheet Compliments of New Century
1-877-79TREES
Peach Leaf Curl
Leaf
curl is a springtime disease that occurs on peach, nectarine and related
ornamental plants. The disease, though
not a problem every spring, can be severe during cool, wet springs that follow
mild winters. The leaf curl fungus damages peach trees by causing an early leaf
drop. This weakens the trees, making them more susceptible to other diseases
and to winter injury. Weakened trees also will produce fewer fruit the
following season. Yield may be further reduced when blossoms and young fruit
become diseased and drop.
Typical symptoms of peach leaf curl.
Note the malformation of infected tissues.
Symptoms
Symptoms
of leaf curl appear in the spring. Developing leaves become severely distorted
(thickened and puckered), and have a reddish or purple cast. Later, as spores
form on the leaf surface, the leaves become powdery gray in color. Shortly
after this, the leaves turn yellow or brown and drop.
There
is no secondary spread of this disease from leaves infected in the spring to
new leaves produced later in the growing season. Once infected leaves drop, no
further symptoms will appear during that growing season. Diseased twigs become swollen
and stunted, and may have a slight golden cast. They usually produce curled
leaves at their tips.
Though
rarely seen, flowers and fruit may also become diseased. They drop shortly
after they are infected. Diseased fruit has shiny, reddish, raised, warty
spots.
Fruit showing signs of peach leaf curl. Note the reddish
raised spots.
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Causal Organism Peach
leaf curl is caused by the fungus, Taphrina
deformans. The fungus survives the winter as
spores (conidia) on bark and buds. .Infection occurs very early in the
growing season. During cool, wet spring weather the conidia infect new leaves
as they emerge from the buds. Host plant tissues are susceptible for only a
short period. As the tissues mature they become resistant. The fungus
produces another type of spore (ascospore) on the
upper surface of the diseased leaves. During wet weather, ascospores produce additional
conidia by budding. These conidia are carried to other parts of the tree by
rain and wind, where they will over winter until the next spring. Environment
can limit leaf curl infection. This partially explains why the disease does
not occur every year. Leaf curl is worse when the weather is cool and wet.
Low temperatures are thought to retard maturation of leaf tissue, thus
prolonging the time infection may occur. The fungus can penetrate young peach
leaves readily at temperatures between 50 and 70 degrees F, but only weakly
below 45 degrees F. Rain is necessary for infection. |
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Control
Leaf
curl is not difficult to control. Since the fungus survives the winter on the
surface of twigs and buds, a fungicide spray, thoroughly covering the entire
tree, will provide control. If leaf curl does result in significant defoliation
in the spring, the fruit on affected trees should be thinned to compensate for
the loss of leaves. Over-cropping the tree will weaken it and make it more
susceptible to winter injury.
Information obtained through the Ohio State Extension Factsheet HYG-3006-94
Insect
and Disease Fact Sheet Compliments of New Century
1-877-79TREES