[Grubbypaws]

My parsnips have been brilliant this year with most looking as good as the 2 in the first photo  but I have just lifted one that was very poorly as you can see in the second photo. Does an one know what is wrong with it and if there is something I need to do to prevent others now and future from looking the same?

[jaydig]

Looks like canker to me, but I may be wrong.

[Grubbypaws]

Looks like canker to me, but I may be wrong.

Yep just googled some pictures of canker and I am sure that you are correct. Do I need to do anything to the raised bed that they were grown in before sewing seeds next year?
What has caused it; all the others have been super healthy and big?

[DD.]

I wouldn't stick a needle in my seeds next year. 

You often get a bit of canker in parsnips and it's nothing  really to worry about. It can be caused by a secondary infection from carrot root fly getting into the parsnip. I tend to grow my carrots & parsnips together under mesh.