Comandra Rust - Cronartium comandrae
Comandra rust canker on the main stem of pine.
Microscopic view of aeciospores. The shape of these aeciospores is different from those of other stem rusts.
Alternate host - Comandra umbellata
Sweetfern Rust - Cronartium comptoniae
Sweetfern rust on main stem of pine. Infection is restricted to the lower bole.
Seedlings infected with sweetfern rust. The top seedling is at the stage where pycnia are produced. The bottom seedling has aecia.
Sweetfern, Comptonia aspenifolia, is an alternate host for this rust.
Sweet gale, Myrica gale, is another alternate host.
Stalactiform Rust - Cronartium coleosporioides
Main stem infection on pine.
Cowwheat, Melampyrum lineare, is an alternate host.
Indian paint brush, Castilleja species is another alternate host.