[bayleaf]

Two of my five apple cordons have canker real bad.   They are four years old. The canker is in the main stem about third to half way up. Should I get rid and start again or is there an alternative solution which is better?

[muntjac]

can you cut the bad out and seal with woundheal preferably a canker curing one ? if so you could bring newer branches up to preserve the trees?   also really good hygiene is  neccasary with this problem get rid of diseased wood by burning it and try to keep a space between trees ,birds can even spread it .another thing is actually buying in the dang thing on the roots from tree suppliers ,grafting can also be tried .taking sound wood from the top sections and grafting it after the bad wood  i dont know a great deal about this so maybe others can help .i have fruit trees but am fortunate in not having any problems ..YET !!!!!

[penance]

can you cut the bad out and seal with woundheal preferably a canker curing one ?

No no, wound seal treatment was shown a long time ago to cause more harm than good. It more often than not seals in harmful bacteria or spores and in some cases stops the codit from working correctly.

Im afraid the only cure is to remove infected wood, but do not do it during the winter. This time of year is when the fungal canker spores will be floating around, they will enter via a wound and you will be no better off.
As muntjac said, burn all infected wood as soon as it is removed.
Also be vigilant on removing fallen leaves.
I have been asked quite a few times to treat canker infected prunus, mostly the tree looks very odd after due to the removal of infected branches, and sadly they tend not to live to long after.
I mostly recomended removal of the tree, sad but the only true way to get rid of canker.

Grafting is not easy, in particular if it is large section wood.

Any remaining fruit trees near by should be treated with a bordeaux mixture spray at bud time in spring, obviously this is only practical for small trees.

[muntjac]

thanks for the update penance  

[bayleaf]

Thanks for your advice guys. I thought they would have to go but it was good to get the info that confirms this.
Cheers