Galls slowly enlarge each year. During the spring blister-like fruiting bodies break through the pine bark releasing yellow spores, which are spread by wind and infect the leaves of oaks, the alternate host. Orange specks develop on the underside of the oak leaves. In early spring spores are spread back to pines by wind. P. echinata and P. alustris are resistant to fusiform rust.
Chemical control is usually neither necessary nor practical.
This disease is caused by the fungus Cronartium quercuum . On Southern pines the disease is sometimes confused with fusiform rust. Infection results in the formation of spherical galls, which completely surround the stem. The galls disrupt the sap flow, often girdling and killing the part of the tree above it. Trees are greatly weakened and subject to wind damage.