Rose Buds dropping off!!
 

I have a double flat pink rose with fantastic perfume (sorry don't know
name) growing up a fence. The very thorny rose was in the garden when
we moved in 6 years ago and had 3/4 years without problem.
Three year ago the buds formed up till 5-8 mm diameter then all fell
off.
Last year we had a few blooms but lost 80%.
This year all was well till this week when I noticed them dropping off
again.
The buds turn black and I cannot see anything eating them. I have now
sprayed it with a systemic fungicide just in case it helps!!
Can anyone tell me the likely causes and action I should take to save my
last few blooms?
Thanks
--
Peter Hemmings