Rust Small, yellowish-orange areas of powdery spores form on the underside of leaves. These spores spread to the alternate host, hemlock. Melampsora No control is recommended since little damage occurs. Scab and Shoot Blight Branch tips and young leaves blacken and die rapidly. Olive-green spores of the fungus develop on the surface of dead and dying tissue.
Small trees are most susceptible.
Venturia tremulae Remove severely infected trees.