Photinia red robin leaf spot?

HappyHealthyPlants

I have a row of red robins planted at the front of my garden which borders a path and a road into the town I live in. The plants have been in for 2 years now, after struggling in the cold winter of 2018 several almost died. They have all grown now however last autumn we noticed leaf spot, I use a treatment every few weeks. Having removed the worst infected leaves often hundreds (not all as there would be none left) the new growth coming through this year has black ends which are crispy on many of the plants. 

What’s best to do? Should I prune hard? Remove all leaves? The plants are approx 80cm-1m tall. 

I’m hoping that the spring weather may allow me to revitalise the plants.

BobTheGardener

They don't look happy at all, do they?  I think I'd lift at least a couple of them, inspect the roots for any rot or pests and, if clear, pot them up to see if their health improves.  If so, there may be something about the position (eg open and windy - they need a bit of shelter) or soil (a couple of varieties don't like chalk) which they don't like.  If all else fails, I'd dig them up and fork in a substantial amount of well-rotted manure before replanting them.