Photinia - disease or shock ?

Hi, thank you for allowing me to join Gardeners Corner, I was hoping for some advice regarding some Photonias I have in my Garden, they are dropping leaves and as the picture shows, have some discolouration to the leaves. I’ve tried reading up on it but am unsure as to whether it is black spot or shock ?
If it is shock, what could cause it and how can I cure or prevent it happening again ?
They are planted in a row close to a perimeter fence.
Many thanks in advance for any advice.
Regards
Chris (Norfolk)

 

It could be shock over winter but looks more likely photinia Leaf spot. Photinia leaf spot is a fungus attack and the best way of tackling it is good general garden hygiene, stop /slow the cycle of the fungus by cleaning up any fallen leaves and I would mulch with compost in autumn or late winter. They is probably a spray for something like this but what I've mentioned before is more valuable in the long run, the spray is a prevention not a cure just like cleaning the leaves up .

I'd clean up any fallen leaves now and apply a feed could be fish blood and bone / growmore / chicken pellets / others ( not bonemeal ) , fork it or mix it up gently with the soil around the shrub and apply a mulch of compost. Any leaves affected will eventually fall off so keep an eye on them .

If the photinia is planted in a damp cold shady corner you may have to remove and try something else . Worth a go at what I've mentioned above though .