Peach Leaf Curl and Oak Leaf Blister:
Taphrina strikes again
Tom Creswell, Plant Disease Diagnostician and Director,
Each year around late May or early
June we see leaves of peach, plum and oak start to show distortion,
cupping and blister like growths. These abnormal areas usually
start out pale green or perhaps tinged pink or purple, but over
the course of 2-3 weeks they turn dark and necrotic. The cause?
A fungus known as Taphrina sp. This fungus is also known to infect
Maple, Beach, Hop Hornbeam, Poplar, Sumac, American Elm, Hazelnut
On oak the problem is known as oak leaf blister
and it’s a
minor issue on trees that are healthy otherwise. It may cause some
leaf drop but won’t seriously harm the tree.
It’s called peach leaf curl on peach,
and plum pockets when seen on plum fruit. These infections happen
sporadically in home plantings and are rarely a significant problem
in orchards that are routinely sprayed for other fungal problems.
On non-sprayed stone-fruit trees it may cause leaf drop, minor
twig death and weaken the tree, making them less resistant to
other problems. By the time the symptoms show up in the spring
it is too late to spray for this disease.
Spores overwinter on leaf buds and infect
leaves as they open. Only one infection cycle occurs each season,
and mature leaves become resistant to infection. Cool and rainy
spring conditions favor infection. No control is needed on most
ornamental trees since the disease is brief and causes no real
harm. Plants in the nursery may need to be sprayed to keep them
in good shape for sales.
Spores spend the winter on leaf buds and infect leaves as they
open in the spring. Because of this there is little value in cultural
controls like raking and getting rid of infected leaves.
The following websites offer more information on this group of