All of my miniature roses have developed brown speckled leaves. I have used a fungicide and now there is no leaves and green stems
. Can I cut them back to several inches above the ground or what do I do
I would just prune off any brown to black cane material and leave what leaves you can that still look pretty good. The roses may have some stress shock going on. If they are still in the pot you purchased them in, it is likely time to either move them into bigger pots or move them to an outdoor rose bed. If they have dropped all of their leaves and only have the little stems/canes left, I would go ahead and transplant them into bigger pots for now. If the root systems are all very tight and forming into the shape of the old pot, try to break them up a bit gently. You will likely break some of the roots off but that is to be expected with tightly intertwined roots. Place them in the new pot and soils. Water them in nicely with some water that has both a product called Super Thrive and a root stimulator mixed into the same water. Use a fresh batch of this water mix the next 5 to 6 times they need watering. The super thrive helps the roses deal with all sorts of shock and the root stimulator gets the root system growing and establishing. It may take a while before you see things happening on the top side as the roots are working to get established. Once the recovery is well underway the leaves will return. As will some buds and blooms. Once you see the foliage returning nicely, you could transplant the rosebushes to an outdoor garden or rose bed location. If you are keeping them indoors, I highly recommend getting them outside ASAP. Do so slowly to break them in to the outdoor conditions and sunshine. Miniature roses are usually pretty tough and hardy.