I think it's fungal too - in John's last pic it seems like the furry white stuff is emerging from little bumps within the leaf and growing spores (and there are lots of tiny white spots in the leaf itself).
When you read the second link that bcday posted, the description fits, altho the pics don't, yet it would be interesting to see what this leaf looks like in another couple weeks.
The fact that it is mostly affecting C. chinenses could mean that chinense foliage type is simply more susceptible to this particluar pathogen.
PP
|