Rust on Tall Grass beside Pond

Plant diseases
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Lancashire Lad
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Rust on Tall Grass beside Pond

Post by Lancashire Lad » Thu Jul 16, 2015 11:19 am

Found last week: -

I'm not holding my breath on getting a species ID for this one. :) - but any suggestions will be much appreciated.

The rust was almost certainly the uredosori/uredospore stage of whatever species.
Appearing as contiguous chocolate brown pulverulent sori on the undersides of the grass leaves.

The grass - which I thought would be easy to identify, proved not so! Although my best guess would be one of the Oat Grasses.
It was growing amongst Iris pseudacorus, in very wet soil, practically in the marginal area of a small pond.
Overall height of the grass to approximately 1 metre, width of leaves to approximately 10mm.

I only discovered that the close shot of the head of the grass was not sharp when I got it onto the computer - so too late to take another shot.
But I think it still might show useful features - such as the long awns (hairs) on the lemma/glume.

Click on images to view at full size.
Grass (a).jpg
Grass (b).jpg
Uredospores from Sori on Grass Leaf.jpg
Regards,
Mike.
Common sense is not so common.

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Chris Yeates
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Re: Rust on Tall Grass beside Pond

Post by Chris Yeates » Fri Jul 17, 2015 11:24 pm

Hi Mike
the grass could be Brachypodium sylvaticum (though that habitat is scarcely typical . . . .). In which case you would need to note whether there are capitate paraphyses around the uredosori.
Rusts on grasses (especially stage II) are not always easy, and if you are unsure about the host then . . . .
Although Puccinia brachypodii var brachypodii is not supposed to occur on B. pinnatum (Tor Grass) in this country according to published works (e.g. Henderson's BMS booklets), I have seen it on several occasions, including http://www.fieldmycology.net/FRDBI/FRDB ... rachypodii
regards
Chris
"You must know it's right, the spore is on the wind tonight"
Steely Dan - "Rose Darling"

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Re: Rust on Tall Grass beside Pond

Post by Lancashire Lad » Sun Jul 19, 2015 6:00 pm

Thanks for the suggestion Chris.

I don't think that the grass can be Brachypodium sylvaticum though, as (from what I've read) it didn't have the typical clump of leaves at the base, just three or four leaves spread evenly up the stems, and maybe five or six stems close together.

With a bit of luck, I'll be able to get back to the site and will collect a full stem, roots and all, and will then try to come to some sort of conclusion as to what species of grass it might be.

Regards,
Mike.
Common sense is not so common.

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