Experts and BHG readers answer.
Why is my magnolia crying?
I suspect that your magnolia tree has insects that are exuding honeydew. Either aphids or scale insects could be the cause. Examine the plant closely for presence of either. Aphids would be on the leaves out at stem tips. Scale insects would most likely be on the branches themselves, and would look like raised bumps. Aphids are much easier to control than scale. Insecticidal soap is usually effective in controlling them. Scale is protected under its scaly armor, so most insecticides are ineffective except when new scale insects hatch out. So you need to watch for the crawler stage, and spray at that time