Southern Fusiform Rust

Description:

Galls on branches (image #1) and trunks (images #2, #3) of young Loblolly pines (Pinus taeda) appear as swollen ‘Fusiform’ or spindle-shaped areas up to six inches long. Bark has expanded with areas of orange (aecia) beneath. These aecia are hard until the spores mature, at which time the bodies aecia (image #1), releasing large quantities of orange aeciospores, approximately 30 µ x 20 µ in size (image #5).

Habitat:

Galls occurring on branches and trunks of young Loblolly pines in an open field.

Notes:

Southern Fusiform Rust occurs more frequently in trees young than 10 years. The disease is heteroecious, requiring two hosts, pine trees and oak trees, and occurs in five stages: Pycnial Stage, formation of pycnia under the epidermal lays and release pycniospores in orange viscous fluid in September-February. Aecial Stage. Large numbers of aeciaospores are produced in the galls, and are released in February-April. Uredial Stage. Aeciospores infect oak leaes and, after approximately 2 weeks, uredia - pale green spots - are formed on the undersides of leaves. Uredia rupture epidermal layers of the leaves and release urediospores that reinfect oaks. Telial Stage. Telia/teliospores, produced in February-June, are hair-like, black chains of teliospores which overwinter. Basidial Stage. Teliospores germinate and produce wind-borne basidiospores, in early April-June, that complete the cycle by infecting susceptible pines. Loblolly Pines are particularly susceptible to Southern Fusiform Rust infections.