I had couple of small rose bushes that were planted last year in my front garden and were looking very healthy. Three weeks ago, my well-meaning parents were house-sitting and while doing a bit of weeding they noticed that soil was quite poor, so they mixed in a lot of all-purpose plant feed pellets around the base of the roses. A week later, and all the leaves had turned brown. Now the stems are bare. I can only assume it was down to the pellets? Is there any hope of saving them?