Frustrating Rose plant

Bought a lovely rose tree about six years ago - had two years of beautiful and plentiful creamy white flowers. Now we get plenty of flowers but before long they go “mouldy” - we’ve tried ordinary Rose pesticide but no success - beginning to think we should dig up and start again. Apologies , not an experienced rose gardener and don’t have details of type of rose. Photos enclosed...

 

Looks like botrytis blight to me. Can you see anything grey and fuzzy on the blooms?

 

Yes - a sort of grey dampness inside the flowers which seems to turn rusty brown once dried...is that consistent with botrytis ?

 

Are you getting a lot of rain?

 

No more than anyone else - west London - it has been like this for five years so doubt its weather related though I’m certainly no expert ...

 

To me it looks like " balling ". That's when the flowers get excessively wet and the moisture just sits there and doesn't evaporate. It turns the flowers into " balls " of petals that can't open. Most common causes are either rain or being sprayed with a hosepipe etc. I am wondering if it's down to your watering methods, try not to get too much moisture on the flowers. Also, what I do after a lot of rain is gently shake the branches so any excess runs off.
For now, just cut the flowering stems off as you would normally, say if you're deadheading or cutting them for indoor use.

I don't think it needs any sort of spraying at all, just careful watering

 

It is. Botrytis can cause balling, so it might be difficult to tell whether you need to spray or not.

Personally I would to be on the safe side, but it's really up to you. The more important thing is what @KFF said - deadhead promptly, and keep them well-spaced and dry. That's good advice for all roses really - there's at least 3 nasty fungal things that can happen to roses when they get too wet (botrytis, powdery mildew, and black spot).

What I would do is to treat the deadheading and any fallen matter as "infected", just in case - so clean it up quickly, don't put it in your garden waste bin, and burn it if you can. That way if it is botrytis, it won't spread.