Observation 22388: Gymnosporangium libocedri (Henn.) F. Kern
When: 2009-06-13
No herbarium specimen
0 Sequences

Proposed Names

33% (5)
Recognized by sight
21% (3)
Recognized by sight: At least seven species of Gymnosporangium use serviceberry (Amelanchier sp.) as the alternate host in their life cycle. It serves as the host for the aecia stage and the primary host is Juniper.
Used references: 1. Bega, R. V. 1978. Diseases of Pacific Coast Conifers. Agriculture Handbook No. 521. U. S. Gov’t. Printing Office, Washington D. C. 206p.
2. Funk, A. 1985. Foliar Fungi of Western Trees. Canadian Forestry Service, Victoria, B. C. 159p.
3. Ziller, W. G. 1974. The Tree Rusts of Western Canada. Canadian Forestry Service Pub. No. 1329. Pacific Forest Research Centre, Victoria, B. C. 272p.
-1% (2)
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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Pacific Coast Pear Rust
By: Darvin DeShazer (darv)
2011-06-21 10:01:11 PDT (-0700)

The common name for Gymnosporangium libocedri is Pacific Coast Pear Rust and it has been verify from El Dorado County, California on Amelanchier as reported in the California Plant Pest & Disease Report, Vol 24: 48. (2007).

A photo similar to Alan’s showing this stage of Pacific Coast Pear Rust.
Click on the small photo to enlarge it and see the detail.

Andreas – States 0 & 1 make pycniospres (spermatia) and aeciospores and this might be state 3, which makes urediniospores. I’m not sure because I’ve NOT found a decent publication that shows all of the stages of the life cycle in one set of photos.

No Gymnosporangium
By: Andreas Gminder (mollisia)
2009-06-21 00:50:12 PDT (-0700)

Gymnosporangium is occuring in the 0,I state on different pears and related shrubs and trees. The 0,I states look very different from the discomycete-like structures of the Puccina shown here. It makes coloured spots on the underside of the leaves where some hairy protrudings are borne. Look for comparism e.g. here: http://www.biolib.cz/IMG/GAL/70323.jpg

The shrub looks a lot like Amelanchier alnifolia.
By: Daryl Thompson (woobs)
2009-06-20 18:44:39 PDT (-0700)

In British Columbia we called this Saskatoon Berry. The parallel venation in the leaves, the teeth along the outer margin, even the sheen (although somewhat dulled by the infection)resemble Saskatoon Berry, as do the berries themselves. I’m not familiar with the southern range of Amelanchier alnifolia, but it sounds as though Shasta-Trinity National Forest is in the mountains and therefore similar to a more northerly climate. As for the rust, if that’s what it is, I haven’t a clue!

Rust & bug
By: Darvin DeShazer (darv)
2009-06-20 13:58:54 PDT (-0700)

The orange is a rust and the fluffy white looks like an insect larvae case. Do you know the plant? Without a microscope, the rusts are impossible unless the host plant is known.

Created: 2009-06-20 13:10:44 PDT (-0700)
Last modified: 2011-11-17 00:49:40 PST (-0800)
Viewed: 242 times, last viewed: 2017-10-17 11:56:04 PDT (-0700)
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