Rust on Dog Rose

[jaybie]

I found this single sample growing on a dog rose and from what I can find out I think this is Orange Rose Rust- Phragmidium sp. Is this right and is it a fungus or a gall (or a fungal induced gall)?



Thanks for any help, JohnB

[Lancashire Lad]

Hi John,

I would agree with your Phragmidium sp. ID.

It is a type of rust fungus, rather than a gall.

Likely P. mucronatum, but there is a lesser chance that it could be P. tuberculatum. - Although microscopy would be required to be certain.

Looks very similar to this, which I found last year: -


Regards,
Mike.

[ashgale]

i read somewhere recently that P. mucronatum is more frequently found on the wild variety and P.tubercalatum is more typical on cultivated roses,
which, if correct might help narrow it down a bit ?
i cant remember where i read this and didn't make a note either


ashgale

[Chris Yeates]

Originally Posted by ashgale

i read somewhere recently that P. mucronatum is more frequently found on the wild variety and P.tubercalatum is more typical on cultivated roses,
which, if correct might help narrow it down a bit ?
i cant remember where i read this and didn't make a note either


ashgale

hi

(don't forget there is a plant parasites thread - sticky at top of page)

the safest way to tell these apart is by examination of the teliospores (the 'chocolate/black' spore stage), later in the year; as opposed to most of the rusts you do need microscopy with these two

if anyone would like a copy of my rusts review (in PDF form) do let me know via PM

cheers

Chris

[jaybie]

Thanks all for the input.

Chris, I will need to spend a bit of time reading through the sticky - looks like some good stuff in there.

JohnB