Arum maculatum: a full set

Plant diseases
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Simon Horsnall
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Arum maculatum: a full set

Post by Simon Horsnall » Wed Apr 18, 2018 1:34 pm

So I went out today in the hope of finding several of the microfungi associated with Ficaria verna given the excellent information posted by Chris last year and everybody else's finds. Unfortunately, I managed only Uromyces dactylidis. However, I did manage what I think is a full set for Arum maculatum.

Puccinia sessilis, I didn't photograph this one.
Ramularia ari, this is the one I am least confident on but it looks very Ramularia like.


Melanustilospora ari, I have checked the black pustules and they do contain spores so I am fairly confident on the determination. I understand this represents a considerable expansion on its known range.
Attachments
IMG_0344.JPG
Ramularia ari

Simon Horsnall
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Re: Arum maculatum: a full set

Post by Simon Horsnall » Wed Apr 18, 2018 1:37 pm

Forgot to add: SK4841, Cossall, VC56, 18/iv/2018
IMG_0329.JPG
Melanustilospora ari upperside

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Chris Yeates
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Re: Arum maculatum: a full set

Post by Chris Yeates » Fri Apr 20, 2018 5:41 pm

Hi
I won't comment until I can see the pics - not your fault, I fully appreciate, Simon. Do you have images of the smut spores?

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

Simon Horsnall
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Re: Arum maculatum: a full set

Post by Simon Horsnall » Tue May 01, 2018 11:20 am

I shall try again. Unfortunately, I cannot get images of the smut spores. What looks like a very good spore through the eyepiece looks like a blob of gunk through the camera. I really need to improve my micrograph technique.

I collected fresh material today from the same plants so if anybody would care to look at a dried sample, I am happy to send.
Attachments
IMG_0344.JPG
Ramularia ari
IMG_0329.JPG
Melanustilospora ari upperside
IMG_0331.JPG
Melanustilospora ari underside

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Chris Yeates
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Location: Huddersfield, West Yorkshire

Re: Arum maculatum: a full set

Post by Chris Yeates » Tue May 01, 2018 9:51 pm

Hi
Not easy to see but the Ramularia looks to be OK - I think I can make out the white tufts of conidia. I think the dark markings on the other hand are simple anthocyanin pigmentation, very often seen on Arum maculatum; a good clue is that thin dark margin to the leaf - again due to anthocyanin pigmentation. Vanky in his monumental book on European smut fungi (1994) talks of lead-coloured pustules; these are not pustules but depressions in the leaf. There appear to be a lot of misdentifications on the web, which doesn't help matters.

Perhaps the "gunk" is made up of the pigmented cells of the plant, true ustilospores would be quite distinct, obvious, and float around in a water mount.

Sorry but that's my honest opinion; I'd be happy to look at specimens for you, and next time I come across a spotted Arum leaf - they're pretty frequent in this part of West Yorkshire - I'll try and do a mount, just to see what the pigmented plant cells look like.

Here is the relevant image from Vanky (1994):
Mel-ari.jpg
Mel-ari.jpg (23.65 KiB) Viewed 1347 times
Regards
Chris
"You must know it's right, the spore is on the wind tonight"
Steely Dan - "Rose Darling"

Simon Horsnall
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Re: Arum maculatum: a full set

Post by Simon Horsnall » Wed May 02, 2018 8:15 am

Thanks Chris for your opinion.

I was lead to believe that the spotting (very common round here too) was different to the sunken depressions as the spotting tends not to be visible as greyish markings on the underside (this is how I initially screened the leaves).

When I say gunk, they look reminiscent of WW2 sea mines down the eyepiece, I just can't seem to get the lighting/focus correct to get a decent image through the camera.

Anyway, I am willing to bow to your superior knowledge.

Simon

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