are you asking if you can use the old mature understock already there .. and add the resistant type????

ken

Yeah that's what he's asking. He wants to graft from a more-resistant type. The answer is no. Surely you could graft a more-resistant type but there will be no flow of "DNA" to help combat the already disease-prone 30-year trees.

Best Regards,

Dax

i was picturing him cutting the stump to 3 feet.. and grafting a few new pieces on ...

is that possible.. imagine the root mass on those fresh grafts.. lol ... probably shoot right out of the graft .. lol.. 45 caliber grafts ...

ken

Ken, it is possible, and people do it to make use of established rootstock, but it does look strange:

http://www.infobharti.com/how-and-why/plants-and-animals/can-one-tree-produce-the-fruit-of-a-different-tree.php

To the OP, Dax is correct...only the branches you graft on would have resistance.

Alex

Here is a link that might be useful: cleft grafts

Youtube has a pretty good cleft graft demo video, for anyone interested.

In this case though, it sounds like replacement of the entire tree with a disease resistant cultivar might be better.

Here is a link that might be useful: Fruitwise apple tree grafting, the cleft graft

Wow, thanks everyone for all of the excellent info! From the video, it looks possible, but I think that would look terrible in the front yard. I'd rather deal with the leaf drop at this point, lol...

That's some funny sheeeeaaaat Ken. Pretty much true actually!

Dax