[Grubbypaws]

I planted 3 polkas last year and one of them has started to look very poorly.

Its leaves are yellowing with brown edges and the new cane is black along one side. They are next to a wall so should have been dryish over winter and are now drip watered. Could this be root rot? If so what should I do? The temptation is to dig it up and hope its neighbours are not also affected.

Help!

[Trillium]

No, not root rot. Simply dying from excessive dryness too long and at a crucial time. Raspberries, being shallow rooted, can't survive their first 2 years without adequate water. Once they've got their larger root systems spread out, they'll cope better with dryness but that will affect how they fruit, which will be small and few.
You'd be better off to move the rest to a location where they'd get regular rain or a drippy tap or something. The one in trouble now may or may not make it but if you cut it down to about 3-4" and keep it watered, it might recover.

[Grubbypaws]

Ever since May I have had the drip hose on. I thought they liked to be dry in winter and well watered in summer so thats what i have done. It is one of 9 plants in a row and all the others seem fine.