Landscape and Nursery - Fusiform Rust of Pine

The following is information on a rust disease we are currently seeing in pines.

Fusiform rust of pine is caused by the fungus Cronartium fusiforme, and is widely distributed in southern states up to Maryland and Delaware. Infections result in swollen, spindle-shaped (or oval) galls on branches of the pines with orange spore production in the spring. Loblolly and slash pine are both very susceptible. The disease may kill trees less than ten years of age, and cause deformed branches on older trees. This fungus requires an alternate host, oak, and there are usually oaks in the vicinity of infected pines. Black and red oaks are the most susceptible and symptoms occur only on the leaves. The best control is the use of resistant varieties. Pruning of infected branches or rouging out of infected pines will reduce infection. Some years may be worse than others for infection and sporulation. Do not fertilize infected trees and stimulate excess growth.



Nancy Gregory, Extension Plant Diagnostician, Department of Plant & Soil Sciences, University of Delaware