What is happening to my lovely Spirea?

Well I noticed my spirea wasn't quite looking it's usual lovely self this morning, I gave it a water as it has been quite dry, then I noticed that some of the leaves were curling with silvery underside and in the worse effected area a sort of white power. I assume it is some sort of fungal problem any idea how I treat, I don't want to lose this lovely big shrub.





Love EGW x

 

It looks like a mildew, not seen it before on mine. I would cut out the afected branches and burn them. One thing about Spirea, it can handle a good prune.

 

Hi Celia, thank you very much for your reply. on closer inspection there was quite a lot of infected brances - I have cut most out. From what I have read it was quite dense with a lot of new growth (serves me right for feeding it - never bothered before) so I think this is the cause. I have sprayed with a fungus fighter as I really don't want to lose it as it is a well established big shrub. My garden is a fungus haven, half of my other plants have rust