Charlottes with mushy middle

My Charlottes have been great up to now, but I was dissapointed and a bit worried with yesterday's harvest. The largest potatoes of the crop looked great, but when I cut them in half for the pan, the middles were mushy, surrounded by a pale brown ring. Any idea what this is? Going back tomorrow to get some more and see what they are like.

Any advice would be great!

Sounds like they have grown really big and have what we call hollow heart. This sometimes happens if they get too big. I think off the top of my head that it can be caused by a lack of Boron. If the seed is Scottish you should not have brown rot.

Lack of Boron does cause brown hearts in sweeds and hollow stems in cauliflowers so that might be logical Iain.

(That's a nice web site, I've added it to our 'useful' sticky)

still got 2 full rows of Charlotte in the ground. Is it time to pull them all up? Do you think my main crop (King Edwards) will be affected? 

Thanks for the advice guys, I'll seek out some foliar feed (with added boron!) tomorrow. Fingers crossed I'm not too late 

I use Wilkinsons liquid growmore (must get some more)  it has boron on the list of nutrients.