I have been growing Roses for a few years and I recently planted a new bush at the end of my flower bed, after removing an old one that never did well in that area(I thought it was the bush). The new bush died, the 2nd one died and now I am on the third and it may die. It is turning the leaves a little brown at the base of the plant before it travels up and kills the rest. The other four bushes in the SAME flower bed are fine. What can it be? And can it only be at one end of the flower bed and its only been the last few weeks. It wasn't killing roses in that one area before a couple of months ago. And it is getting plenty of water. If it is a fungus what do I use? Thank you very much!!