Spots on my Camellia
My husband was complaining that the Camellia bush by the garage was putting black spots on his truck hood. So yesterday we looked at the bush to see how it could be cut back so branches don't hover over the hood of the truck. Upon close investigation I found the spots on his truck must be from the black spots on the bush. This is the first year I have ever notices them I will cut back some branches as it just about finished blooming but think some other intervention is needed. Please advise.
Howard County Maryland
The black substance looks like sooty mold, which is a symptom but not the problem.
The problem is probably an insect called scale. In this case, cottony camellia scale.
Scale insects have a cover over their body, much like a turtle has a shell. Some excrete a sweet substance called honeydew. This drops down on leaves and then a fungus starts living in it. That is the sooty mold that makes the leaves look black. The sooty mold eventually washes off with rainfall, but it is unsightly and shades the leaves a bit.
However, the real problem is the scale insects because they are sucking insects that suck the juices out of your plant. Here's more: https://extension.umd.edu/hgic/topics/cottony-camellia-scale-shrubs
To verify this diagnosis, you are invited to send close-up photos of the leaf undersides and stems.
We looked at your photos. We cannot for sure what is covering the top of the foliage. It may be granular particulates from the roof or soil that is being splashed.
Top left photo on the leaf underside - this looks like a type of scale insect, called cottony camellia scale. It is a sucking insect that exudes sap as it feeds and this fosters the growth of a black sooty mold. Here is our webpage for photos and control https://extension.umd.edu/hgic/topics/cottony-camellia-scale-shrubs
Monitor the new growth, look for evidence of scale insects, as per the above links. You can attach double sided sticky tape to the branches to monitor for crawlers. When you see the crawlers, you can spray with a summer rate of horticultural oil. Follow label directions.