Question
Recently I purchased a few rose bushes on clearance sale at a local store. They looked kinda bad, but thought all they needed was some TLC. The stems are turning black & the leaves are drying out. Some of them have yellow leaves, or black spotted leaves. Do you possibly know what these problems are, and what I can do to save them? Two of these are rose trees. Don't know if they are treated any different than a regular rose bush.

Answer
The black and yellow spotted leaves are probably black spot, which is a fungal disease. The black stems could be also be black spot or another fungal canker disease.  Sounds like you have your work cut out for you.  If it is possible, prune off the dead and dying plant material down to where there is healthy growth.  Destroy this material somewhere away from those plants.  You can then purchase a Bayer Advanced Rose Spray from Home Depot and treat the plants with this product.  It should contain both a fungicide and an insecticide.  There is no guarantee they can be saved, but you can try.  I hope this helps.  Good Luck.