Camellia shrub

Question

My camellia shrub has just developed black edges around perfectly green leaves. I would like to know what causes the leaves to blacken on the outside.

Answer 1

This could be sooty mold, a fungal growth caused by insect infestation:

https://www.gardeningknowhow.com/ornamental/flowers/camellia/sooty-mold-on-camellia.htm

Alternatively, it could be physical damage from a heat wave, or from high salt or fertilizer content in the soil:

https://www.gardeningknowhow.com/plant-problems/environmental/what-causes-brown-edges-on-leaves-of-plant.htm