Pine-Oak Gall Rust
(Eastern Gall Rust)
Symptoms and damage
The fungus Cronartiumquercuum causes gall rust on approximately 25
to 30 species of pine and oak. Infection of oak causes small brown or yellowing
areas on the leaves. On the underside of the leaves, yellow to orange powder
(spores) is visible.
All fungal spores, which infect both pine and oak, are primarily
windborne. High humidity increases the incidence of infection. Chemical control
is usually not warranted. The fungicide myclobutanil
may be applied to oaks according to the directions on the label. Follow the
directions on the label..