Observation 156251: Ascomycota Caval.-Sm.

When: 2013-12-21

Collection location: Tahoe National Forest, California, USA [Click for map]

Who: Byrain

Specimen available

Notes:
Found on fallen Arbutus menziesii (madrone) leaves near the mushroom expo.

Conidia hyaline & mostly uniseptate.
Conidia range = (21) 22 – 29 (30) x 5.5 – 7 µm
Average conidium = 25.45 × 6.03 µ
Q range = 3.5 – 5.09
Average Q = 4.24
20 conidia measured in H2O.

I’m not sure this species is in ’Westcott’s Plant Disease Handbook’ & I see nothing known from Arbutus at all in Ellis & Ellis.

Images

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Pycnidium, 100x, Mounted in H2O
Conidia, 1000x, Mounted in H2O
Conidia, 1000x, Mounted in H2O

Proposed Names

57% (1)
Recognized by sight

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= Observer’s choice
= Current consensus

Comments

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Re: Paper on Madrone diseases (Edited)
By: Byrain
2013-12-26 02:59:58 CST (-0600)

The paper is available online, here.

http://extension.oregonstate.edu/...

It pretty much shows the same options as ’Westcott’s Plant Disease Handbook’. Here are some thoughts on the options:

Ascochyta hanseni – With brownish & smaller conidia? http://bit.ly/1e9Gwi0
Cryptostictis arbuti (= Seimatosporium arbuti) – 4-septate conidia? http://bit.ly/1bp5Htv
Didymosporium arbuticola – “Conidia are slime-spores in acervuli; dark, two-celled.” – Westcott’s Plant Disease Handbook
Mycosphaerella arbuticola – Different macro & conidia. http://bit.ly/19d2ttp
Phyllosticta fimbriata – Far smaller conidia. http://bit.ly/K1cFP6
Diplodia maculata – Short Latin description, maybe? http://bit.ly/JbPsd3

There is also Septoria unedonis known from Arbutus unedo, but I don’t have the description (Desmazières, J.B.H.J. 1847. Quatorzième notice sur les plantes cryptogames récemment découvertes en France. 8:9-37). Septoria images I have found online mostly show different kinds of spores though, maybe similar macro at least…

Edit:

That Diplodia maculata description says it should have brown conidia, also this link corroborates that. http://website.nbm-mnb.ca/...
And the Septoria unedonis description can be seen here on pg. 20, not that it helps very much… http://bibdigital.rjb.csic.es/spa/Libro.php?Libro=2228

I also found this about Septoria, “Most taxonomists adopted a generic concept of Septoria that included fungi forming pycnidial conidiomata with holoblastic, hyaline, smooth-walled conidiogenous cells with sympodial and/or percurrent proliferation and hyaline, smooth, filiform to cylindrical multi-septate conidia (Sutton 1980, Constantinescu 1984, Sutton & Pascoe 1987, 1989, Farr 1991, 1992).”
http://studiesinmycology.org/content/75/1/213.full

Paper on Madrone diseases
By: christopher hodge (christopher hodge)
2013-12-25 23:58:48 CST (-0600)

Bennett, M. and Shaw, D. 2008. Diseases and insect pests of Pacific madrone. OSU Extension Service EC 1619-E

maybe if you can access it there will be reference to this species.