On this forum, you'll often find a lot of emphasis on things of dubious value, like misting and using certain elixirs that in the overall scheme of things will have no measurable impact on your tree's current or future state of vitality. Most plant afflictions ultimately lie within the affects of a very few factors, those being your soil choice, which is inextricably linked to watering habits, light, nutrition, and how you've maintained the root system of your plant. The light and nutrition are pretty easy - you either have or do not have appropriate light. If you have it, that's wonderful; if you don't have it, you'll simply need to accept the limiting effects of inadequate light or supplement, which isn't easy on an 8' tree. Nutrition is also easy, but it leads us right back to your choice of soil (surprised at that?), I can tell you WHAT to fertilize with, but HOW you fertilize and how fertility levels combine with the level of other salts in the soil need more discussion. We can talk more if you're interested. Most importantly - if you can't provide cultural conditions that ensure happy roots, you have no chance of keeping the rest of the plant happy. This leads directly to soil choice and what you've done to maintain roots. This area of container culture, and I'm going to include over-watering with soil choice because of their close association, is rightly where almost all of the problems brought to this forum originate - including pest infestation and various diseases. It sounds probable that your plant is dealing with one of several fungal infections that affect roots. The roots of a plant that old would be climbing out of any size pot if the plant was healthy. If the bark peals away easily exposing what was once living cambium, you can be sure your plant has Southern Blight or any of several other fungal infections associated with this plant. Without being there to see the plant, it's difficult to assess whether the plant is savable or not. You must feel that it is, or you wouldn't be asking for help. The best time to undertake any kind of serious root work on your rubber tree would have been late Jun - late Jul. A picture would be very helpful, otherwise you'd need to unilaterally decide if you think an emergency repot is in order. Repots differ from potting up in that they include removing all (or almost all) the soil from the root mass, and in your case removing any dead/decaying/otherwise compromised root tissues. Trees in the condition yours are in just don't turn around because you decide to fertilize with something special or offer a plant tonic; and misting the foliage isn't going to do it either. It will take some fortitude and your willingness to take a risk, but in your case it sounds like that might the only option to keep the tree from staying its present course. I maintain MANY Ficus in containers, many of them very old specimens, and I maintain them in continual good health because of a good understanding of their needs and what they will/won't tolerate. Let me know if you want to establish a dialog and if you want additional/more specific help. Al

How large is the area affected? If it is brown at the base, cut it off, and cut up until you see good tissue. The material left can probably be rooted by cutting.

I water once a week and wait for the top soil to dry. I use about 2 cups of water. I repotted last month. There were about four stems and they were connected together in a root ball. I figured there might have been over crowding so I tried to separate the plants into two pairs. One pair died and I figured the pot was just too deep and I may have damaged some roots. This plant was dong well for two weeks and since two weeks ago all the leaves started falling off. I place it at an east facing window. I live in San Francisco. I added regular potting soil and removed the old soil. The plant seems to still be holding onto one leaf. I was told by some gardeners that if this last leaf falls of then the plant is dead. I notice that the soil is still very moist and its almost been a week since I watered. If the leaf does fall off, is there a chance that I can still save the plant? Perhaps repot or cut down some roots? It is still connected to the other stem which died already. Any advice for this beginner would be super helpful. Thank you!!

Hard to tell in pictures but what you're describing could be root rot or nothing at all. Overwatering is a pattern over several weeks not just how it's ben treated recently. What kind of potting soil is it planted in and also how big is the diameter of the container? Often times weekly watering can be too much if your container is much larger than appropriate for the size of your plant or if the potting medium retains too much moisture. That being said, Rubber Tree stems do turn brown and woody, and some amount of leaf shedding on the bottom is normal -- so this could all be normal -- need better picture to tell.