Fir Broom Rust
Leaf Rusts of Hardwoods and Needle Rusts of Conifers
Juniper Broom Rust - Gymnosporangium nidus-avis
Juniper with witches' broom.
The telia form firectly on the needles. This photo shows the telia (dark areas) when dry.
Telia on branches from a juniper broom during wet weather. The telia have expanded producing a gelatinous mass which contains the teliospores.
Serviceberry, Amelanchier, is the alternate host for Juniper Broom Rust.
Pycnia are produced on top surface of Amelanchier leaves.
Aecia are produced on the bottom of Amelanchier leaf. The aeciospores infect junipers
Melampsorella causes a withches' broom on fir. The alternate host is chickweed (photo not shown).
Pycnia and aecia are produced on needles of the broom on balsam fir.
A view through the stereoscope showing a needle with pycnia (black dots) and aecia (white structures that produce aeciospores).