I have some basil growing on my deck, and overnight, it developed a strange white substance, not on the plant, but on the soil around the plant. I am thinking it may be some sort of fungus or mold because the weather has been rainy over the past week. Plus, the container is fairly shaded even though the leaves get enough sun.

The picture is a close up of the top of the soil.

Any ideas about how to treat? Or should I just put in new soil and get new plants (don't want to get sick)?