This week we have seen and heard of several oak trees with blister-like growths and deformities on leaves. This disease is called oak leaf blister and it is caused by a fungus named Taphrina caerulescens.
If this description sounds familiar and you've seen it on your oaks, there's no need to panic. Oak leaf blister might make trees look sick, but this disease will not impact the overall health of trees. There is no need to spray or treat your trees. Instead, promote general tree health by adequate watering and fertilization. Vigorous trees will be less prone to severe oak leaf blister infections.
Oak leaf blister causes light green, raised areas on upper leaf surface.
There may be several oak leaf blisters on each leaf.