Problem with a raised bed

I've been busy this year creating a new bed for the garden. I previously used it for onions but I wanted to plant it up this year. I went off and bought a couple of climbing roses from David Austin, a honeysuckle and a couple of clematis from the local garden centre and a shrub rose from b&m. 

All were doing absolutely fine, no sign of any fungal issues, major pest problems and they were all growing and flowering well. All these plants were put in place in spring, they've been watered consistently and fed. I've not had any roses in that space since I put the raised bed in there 4 years ago plus the soil always gets a good compost dressing every spring. 

Over the last couple of days I have noticed some die back on 3 plants that are within 2 metre square of each other. It began with the shrub rose; half of it had dead wood and crisp brown leaves. I passed it off to the weather so pruned the dead wood and cleared the leaves. Today I have noticed that the rest of the shrub rose has started to go brow and that both the honeysuckle and one of the climbing roses have brown leaves.

Does this look fungal related or down to the heat? The bed is facing west so gets full sun from late morning till early evening.