See:
Camellia - Ramorum Leaf Blight and Shoot Dieback
Cause Aside from the physiological oedema problem, there have been a few fungal leaf spots reported from Oregon and Washington including Pestalotia sp. and Phyllosticta sp. These fungi may be colonizing tissue damaged by sunburn or other problems. Several other fungi can cause leaf spots on Camellia but are not common in the Pacific Northwest.
Symptoms Dead necrotic spots, which are large, well defined and sometimes marked with small, black pimple-like fruiting bodies.
Cultural control Remove and destroy old leaves, flowers, and other plant debris, especially under the camellias.
Chemical control Not generally needed but many of the fungicides labeled for flower and petal blight will also be effective on these leaf spots.
Reference Maharachchikumbura, S.S., Chukeatirote, E., Guo, L.D., Crous, P.W., Mckenzie, E.H., and Hyde, K.D. 2013. Pestalotiopsis species associated with Camellia sinensis (tea). Mycotaxon 123:47-61.