Summer fruit veg and flowers

The post title was going to be "Summer raspberry troubles" but I decided to go for something more positive given the number of other crop successes compared to failures.
All the alliums ; onions,garlic etc, seem to be doing well this year including Rossa Lunga sown from seed,and the gooseberries, currants and loganberries which I planted last year are all producing good crops of berries.

Rossa Lunga bulbing onions

Loganberries

Slideshow

The summer raspberries canes (Glen Ample and Leo ) were looking healthy enough a month ago and I even added more stakes to accommodate this year's strong growth.However,they have now become weak and sickly and are starting to die off.I've removed the worst of the canes to see how the rest fare but would welcome anyone's thoughts on what's caused the problem and any possible solutions.It could be root rot or a virus? They might all need digging up and throwing away.I'd hate it if any contamination spread to the loganberries and autumn raspberries.