I have about eight different dahlias, and I left every last one outside over the winter. But this one…

It was planted late last year, never did much, and I knew it wasn’t planted deep enough at the time. I did have a go at digging it out, but it didn’t want to come so I left it.

It is in a deep pot with tulips and ornamental variegated ivy (unknown variety, I found a bit on the pavement/sidewalk that had broken off from a planter, and made it mine) . The tulips did naught but one bloom this year, but I didn’t expect them to. The ivy was going crazy last year, but looks horrible this year.

The dahlia, however, looks like maybe it has a virus?

Lower leaves and stems look normal, but the budding bits of recent weeks look diseased.

So, should I chop all the icky looking parts off and hope new growth is healthy? Or is this entire plant for the bin? 

Other dahlias in pots, thriving and budding within less than a foot of this one are just fine.