What's killing my Russet apple tree? pics inside..

[Lazgaot]

I bought an Ergemot (sp?) Russet Apple tree a couple of years ago from a local garden centre and planted it out on the allotment.

It was about 7ft tall and when I put it in the car the tip of the plant bent and snapped. I didn't think anything of it and planted it out. Over the next few months the bark at the top of the plant turned dark and rough and started to creep down the stem and the small branches started to die off. I thought I'd intercept it and sawed the top of the plant off well below the "rot" to try and stop it. No luck, its still descending and killing off the plant from the top.

Any idea what it is and how I can stop it? Pics are here, here and here.

[purplekat]

I was going to say it's sounds like canker in which case you'd done the right thing in pruning below the rot but after looking at your pictures, I'm not sure it is.

I can't think of anything else you could do, you've already pruned back below the rot and I'm not sure how much more you can prune back.

Does your garden centre have a guarantee on it's plants? - ours has a five year one although you'd have to prove you'd got it from there.