Answer: Ordinary road dust should wash right off the glossy leaves of your camellias. If the residue is sticky, your plant may have an insect problem. Scale insects, whiteflies, and aphids can all leave a sticky substance called honeydew behind. This sticky substance can sometimes turn black (called sooty mold) or it can collect dust and dirt which is difficult to wash off. Check the stems and undersides of the leaves for insects. If you find and control them (the control depends upon the insect population you find), then the honeydew will be eliminated and the road dust should rinse off with plain water. Best wishes with your camellias!
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