Oak Leaf Blister
Symptoms and damage
Oak leaf blister is a disease caused by the fungus Taphrinacaerulescens. Most oak
species are susceptible, but pin oak and the white oak group are especially so.
Minor infections cause little harm, but midsummer defoliation can occur when
infections are severe. Blister-like patches appear on the leaves. They are
often lighter green than the surrounding tissue and later turn brown. The
blister-like patches result from overgrowth of infected leaf tissue, which is caused
by substances secreted by the fungus.
Leaf blister is rarely severe
enough to require control measures. Once infection has occurred, fungicide
treatments usually are ineffective. If infection is very heavy and if the tree
is small enough to obtain good coverage, a fungicide could be applied in the
spring just before bud break.
Examples of Fungicides (Myclobutanil - Neem
Oil – Propiconazole - Thiophanate-methyl