| Peach leaf curl is a springtime disease caused by the
fungus, Taphrina deformans. It infects the leaves and
shoots of peaches and nectarines. Apricots are
immune. It is one of the most common diseases of
these fruits. It causes the leaves to curl and turn
reddish in color. A severe infection can cause
reduced yields.
Symptoms and Diagnosis
Symptoms first appear in spring. New leaves
become curled and develop reddish areas. The
reddish areas become thickened and puckered
resulting in severely distorted leaves. As the disease
progresses, the thickened areas turn yellowish gray
and become covered with velvety spores. Affected
leaves turn yellow or brown and fall prematurely.
Affected shoots usually send out new leaves which
often are unaffected by the disease unless rainy
weather ensues. In more severe infections, shoots
may become thickened and die.
Aphids can also cause leaves to curl. If present, the
insects or cast skins will be evident to the naked eye.
Life Cycle
The fungus overwinters on bud scales, on twigs, and
on fallen infected leaves. In spring the fungal spores
are splashed onto newly developing leaves. During
cool, wet weather the spores germinate on the
young leaves and initiate infection. Development of
the disease slows as temperatures increase. Older
leaves are resistant to infection. Consequently, the
disease is most prevalent in the spring.
Integrated Pest Management Strategies
1. Keep plant healthy — avoid excess fertilization.
A healthy plant can better withstand the loss of
leaves, but excess fertilization can cause
succulent tissue that is very susceptible to
infection.
2. Clean up diseased leaves. Raking up and
disposing of diseased leaves can't hurt, but its
value in controlling the disease is slight.
3. Don't panic.Once infection has occurred
fungicidal sprays are not effective. A healthy plant
should refoliate. Because refoliation normally
occurs during warmer, dryer weather, re-infection
is usually not a problem. Thinning the fruit crop
in years of severe infection can also help
maintain plant vigor. To limit damage the year
after a moderate to severe infection, follow the
protective spray program below.
4. Use properly timed protective fungicidal sprays.
If leaf curl was a problem in the spring, apply a
protective fungicidal spray after leaf fall in
October or November or before bud break in late
winter, January through February. After buds have
begun to swell fungicidal sprays are not
satisfactory. Do not apply to foliage. Chemicals
effective in controlling leaf curl include copperbased
fungicides like Bordeaux mixture, Bravo,
lime-sulfur spray, or other brands that list the
control of peach leaf curl on their label.
5. Replace the tree with a more disease tolerant
variety. If you want to avoid using fungicidal
sprays, consider replacing the tree with a more
tolerant variety. ‘Redhaven’ and cultivars derived
from ‘Redhaven’ have greater tolerance to peach leaf
curl disease. | 
