Rusts from dunes

[adampembs]

Forum a bit quiet, so how’s this to liven things and my apologies for not knowing my plants. 3 rusts found on the dunes.

All leaves are smooth.

Plant A (dunes further from sea)

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Plant B (dunes further from sea)

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Plant C – close to sea – at edge of beach

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Are these fungal? (not the aphids 😆 )

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[Chris Yeates]

Hi Adam

you say you don’t know your plants – but surely the first one 😯

it’s a dandelion Taraxacum offinale (agg.) so it’s between Puccinia variabilis and P. hieracii var. hieracii (you need to check the pores on the uredospores)

second one is Sonchus oleraceus – I would like to see a micro-shot but the dark rings around some of the uredosori strongly suggest Miyagia pseudosphaeria

third one is not a rust (as you suspected), but the galls of the cecidomyid fly Cystiphora sonchi on Sonchus arvensis

cheers

Chris

[adampembs]

1) Lots of dandelion lookalikes, especially in the dunes, well thats my excuse 😳

I can see 2 pores on a lot of the spores, but as to whether they are equatorial or supra equatorial

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2) The Sonchus oleraceus has some interesting microscopy (all in L cotton blue, the last one heated)

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This one heated

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[Chris Yeates]

I know what you mean about rusts on dandelion – I’ve always tended to ignore them in the past, must have another go. I’ll spend a bit of time getting some images re this equilateral / supra-equatorial thing. At least I can see that what I said about staining is making it a bit more straightforward for you – point of attachment showing well . . .

The Sonchus oleraceus rust is showing lovely clavate paraphyses around the uredosori – perfect for Miyagia (as are those rather elongate uredospores). It’s those paraphyses which produce the dark rings I mentioned in my previous post. Once this character has been appreciated you can generally recognise Miyagia in the field with a x10 lens.

cheers

Chris

[adampembs]

Thanks Chris! Last recorded in Pembrokeshire 1928!

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