Stem Rusts


Comandra Rust - Cronartium comandrae

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Comandra rust canker on the main stem of pine.

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Microscopic view of aeciospores. The shape of these aeciospores is different from those of other stem rusts.

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Alternate host - Comandra umbellata

Sweetfern Rust - Cronartium comptoniae

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Sweetfern rust on main stem of pine. Infection is restricted to the lower bole.

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Seedlings infected with sweetfern rust. The top seedling is at the stage where pycnia are produced. The bottom seedling has aecia.

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Sweetfern, Comptonia aspenifolia, is an alternate host for this rust.

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Sweet gale, Myrica gale, is another alternate host.

Stalactiform Rust - Cronartium coleosporioides

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Main stem infection on pine.

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Cowwheat, Melampyrum lineare, is an alternate host.

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Indian paint brush, Castilleja species is another alternate host.