Tuesday, 26 June 2018

Rust on Rosa

Spotted this on some kind of wild Rosa sp. in the car park at work.

The undersides of the leaves are covered in an orange rust, with fuzzy black patches.

Zoom in and those black patches look like this, kinda bushy!

Those black 'bushes' are clumps of teliospores that look like this:

Teliospore mounted in water. 100x magnification.

I reckon what I've got here is Phragmidium tuberculatum. The narrow pointy bit on the end (the 'apical papilla') is a distinctive feature of this species, according to Ellis & Ellis's Microfungi on Land Plants.

For the record
Date: 24/06/2018
Location: Woods Mill, Henfield
Grid reference: TQ218138

Record entered into FRDBI 07/09/2018

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