Question
I live in Memphis, TN (I do not know what zone).  I have recently acquired several rose bushes that are in a container.  Our property has lots of trees and shade.  I keep the rose bushes in a sunny area, but the leaves are tuning yellow with black dots and they are falling off.  Please tell me what is causing this.  Also, how do I get rid of snails?

Thank you

Answer
Two situations are basically causing your problems. The first is that roses hate warm roots and sitting in the sun in a container gives them hot roots. The other is summer is winding down now and the roses would, under normal conditions, start to look poor and drop their leaves.  If you are going to keep them in containers, I would place the roses where they have some shade during the hot part of the day and water them well.
The black dots are a fungus called Black Spot, which is very common at this time of the year. I would wait until spring and then get a spray for Black Spot, and use it  according to the  instructions on the label.
Snails are hard to get rid of permanently, but there is an organic type of snail killer which works very well. Placing a saucer of beer at ground lever near your pots makes a good trap. Here is a website that has more ideas on how to get rid of them or at least keep them away from your plants.
http://www.familymatters.tv/level_4/homeandgarden/snails.htm