Ask-a-Dave's-Gardener: Climbing rose with black spots and yellowing leaves HELP, 4 by vaneperez

vaneperez wrote:
HI, I recently bought a small Zephirine Drouhin climbing rose and It has new growth and buds, but I noticed some leaves are starting to yellow and get black spots also some leaves dropping. I also bought a New Dawn climbing rose and that one seems to be having no problems so I'm unsure of what I am doing wrong. Can anyone recognize if it has disease or could it be that it's because its still in its pot? I am new to roses, the only other ones I have are knock out roses bushes and those are darn near impossible to kill. I did add a tablespoon of Epsom salt to the top soil as I heard they love it and I fertilized them with a flowering fertilizer. Please help! I really want to make sure I get it off to a good start!