Microfungus on Garden Pansy

Please try to include photos to show all parts of the fungus, eg top, stem, and gills.
Note any smells, and associated trees or plants (eg oak, birch). A spore print can be very useful.
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Please do not ask for the identification of fungi for edibility or narcotic purposes. Any help provided by forum members is on the understanding that fungi are not to be consumed. Any deaths or serious poisonings are the responsibility of the person eating or preparing the fungus for others. If it is apparent from a post that the fungus is for eating or smoking etc, the post will be deleted and a warning given. Although many members do eat fungi, no-one would be willing to take someone else's life into their hands.
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Simon Horsnall
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Joined: Mon Sep 14, 2015 3:50 pm

Microfungus on Garden Pansy

Post by Simon Horsnall » Tue Nov 21, 2017 12:16 pm

Can anybody enlighten me on what is causing the spotting on my Garden Pansy, Viola X wittrockiana leaves. I am assuming it is a hyphomycete. Apologies if this should have gone in the plant diseases forum, not quite sure what the protocol is with these.

Location: Ilkeston,VC57
Date: 21/xi/2017
Pale brown, dark-bordered spots becoming zonate with age
Colonies fasciculate, hypophyllous
Conidia hyaline 17 - 25 X 4.5 - 5 microns. At 600X and with careful tweaking of the light, some septa appeared to be present although I could not be absolutely certain how many

Photos of leaf upperside, close up of colonies and micrograph of conidia

Using Ellis and Ellis, I cannot find anything which matches the combination of characters so I've probably done something stupid.
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Chris Yeates
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Location: Huddersfield, West Yorkshire

Re: Microfungus on Garden Pansy

Post by Chris Yeates » Tue Nov 21, 2017 1:42 pm

Hello Simon

Of course you have done nothing stupid; this is a well-presented query. Ellis and Ellis, while excellent, is not complete and there has been a lot of work on these fungi since that book was published. Your fungus is Ramularia agrestis Sacc. I have double checked in Uwe Braun's monumental A Monograph of Cercosporella, Ramularia and Allied Genera, Vol. 2 and the only other taxon associated with Viola x wittrockiana is a var. deflectens (Bres.) U. Braun of the same species.
As far as I can see the chief difference between the latter and the nominal var. agrestis is that it can have up to 4 septa - var. agrestis has 0-1(2) septa. Most stains should clarify the matter.
If you look at the relevant page in Index Fungorum:
Ramagr.jpg
You can see that while both varieties are listed there (IF is a nomenclatural database); it points both to the parent species in Species Fungorum (green text) which is a taxonomic database. For years now this has been the case with virtually every infra-specific taxon. I still cannot understand why Paul Kirk (who is usually a very sensible guy, and a fellow Yorkshireman to boot) does this. Sub-species, varieties et al. can be particularly important categories when dealing with plant pathogens - Mycobank keeps them separate. The "paper-trail" is important with any biological record - what the original recorder called it (even if they were mistaken) should not be lost. Sorry, but this is one of my personal bugbears.

best wishes
Chris
"You must know it's right, the spore is on the wind tonight"
Steely Dan - "Rose Darling"

Simon Horsnall
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Posts: 51
Joined: Mon Sep 14, 2015 3:50 pm

Re: Microfungus on Garden Pansy

Post by Simon Horsnall » Tue Nov 21, 2017 2:44 pm

Many thanks Chris for such a swift, informative and comprehensive reply.

Ellis and Ellis describe R. agrestis as amphigenous and that was where I had ruled it out so yes, something stupid. Next time I shall use that to inform but not eliminate my selection.

I wholeheartedly agree with your sentiments on naming.

I shall try staining the tissues and see if I can determine the number of septa.

Simon Horsnall
Regular user
Posts: 51
Joined: Mon Sep 14, 2015 3:50 pm

Re: Microfungus on Garden Pansy

Post by Simon Horsnall » Wed Nov 22, 2017 10:50 am

Update

After staining in Congo Red, there appears to be 0 - 2 septa (2 being exceptional) in the spores therefore I think we can safely conclude Ramularia agrestis var. agrestis Many thanks once again.

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