I have a magnolia plant. Most of its leaves have fallen off and they turn yellow/black before falling. It also has a cob webby sticky stuff on the branches. I've watered and fertilized it. Its not overly wet. Its also in indirect bright light and the room temp in around 70 degrees. There's nothing on the instructions except do not let the roots sit in water, take it out of the container to water. I got it when my father died in July. Its a real problem to grow. All my other plants are thriving. Got any ideas?

You'll want to check for any pest like spidermites and/or mealies bugs. The mites are small, so you'll need to use a magnifying glass or you hold a white piece of paper under some of the leaves in different spots rubbing the leaves lightly between your fingers, the mites will fall down to the paper and you should be able see them. Mealies look like little white pieces of cotton.

You'll need to spray the entire plant with a soapy water solution from a spray bottle, or, you can use an organic insecticidal soap or an inch of alcohol, the rest water in a spray bottle.
Spray every inch of the plant, get it dripping wet. You'll need to do this once a week for a few weeks to get rid of them.
I would stop fertilizing now because the plant is stressed by what's happening.

The sticky stuff is called "Honeydew" it's waste secreted from the pest after sucking the plant juices from the leaves and stems. It can be all over on the plant and eventually drip onto the floor or onto furniture if the plant is heavily infested, sometimes too infested to save, a real yucky mess!

If your willing to try what might become a long battle to save it,then I'd give it a try. If it's heavily infested, you might want to think about getting rid of it. Make sure that the other plants you have are not infested.