Question
We have several Camellia bushes in our yard and this year we noticed the leaves turning very dark, almost black.  We do know it is something on the leaves beause my wife said she could wipe some of the black off.  Do we have a fungus, desease, and what can we do about it?  We live on the Mississippi Gulf Coast

Answer
Hi Dana,

These are signs typical of sooty mold, a fungal infestation caused (usually) by sucking insects (scale insects, aphids, whiteflies, etc.)  The excretia of these insects is a sticky "honeydew" that serves as a perfect diet for the fungi that cause sooty mold.  In most cases, these fungi do not affect the health of the plants, except to decrease the photosynthetic rate.  It is essential to reduce the insect infestations to control the sooty mold.  The mold can be washed off the plants.

Examine the plants for scale insects as they attach permanently to the plant to feed.  They are usually oval to circular in shape, can be flattened, and they range in color from tan to black.  To the untrained eye, they may appear as "bumps" on the leaves and stems.  

If you find scale insects, consult your garden center for control measures.  Horticultural oils can be used, but they must be used with extreme care as they require specific concentrations for different temperatures.