If mold and fungus has grown from high humidity levels, it should be addressed before more costly damage is done.
Some companies will offer to treat your mold or fungus with a spray only treatment. While this is usually inexpensive, it is a temporary fix. If moisture levels stay high, the mold and fungus will come back to life. The mold is also still visible and worrisome. This is another case where you get exactly what you pay for.
Treating, scrubbing and removing is a solution that will last much longer and leave your crawl-space looking clean and healthy. If the humidity is controlled, the mold will not come back.