Move.

+1
Be prepared to move. Mold can be eliminated and it takes money that the property management firm may not want to shell out.

First, document the current mold problem (pictures, a repair estimate from a mold remediator, etc.). Take this documentation to the property manager and tell him how concerned you are about mold and the related health risks (documentation of health risks -- printouts from government/health websites or something similar -- might help make your point). Remind him that mold can continue to grow even after drywall has been replaced. Suggest that he hire a company that specializes in mold remediation to do the repair, and ask if you can get a statement from the repair company that the mold has been successfully remediated. A large management company should realize that mold can be a health hazard, and they open themselves up to serious liability if they let dangerous mold conditions remain in their property.

There is green and black mold growing on the drywall ceiling of our basement. It looks like there is moisture coming through from between the ceiling and floor above, near the foundation wall. We rent from a large management company. I don't trust them to get all the mold out vs. a patch job. What should I ask for? Thanks!