[NAFEX] multiple apple cultivars on one tree?

Lon J. Rombough lonrom at hevanet.com
Wed Apr 16 23:42:33 EDT 2003


   It's very likely that one or more of the varieties you grafted on the
crab was a symptomless carrier of virus.   There are viruses that have
little or no effect on cultivated apples, but will attack a number of
species of crab apples, causing the death of the tree.  If you peel the bark
off the crab apple, you may find that the wood is pitted, while the wood of
the scion is not.
   I've gotten letters from NAFEX members that were pretty irate about
multiple graft trees as a cause of spreading virus, with some who left the
group because they didn't want to be part of it, or even because they got
virus infected material from someone with a multiple variety tree.  It's
much better to graft one variety per dwarf rootstock than a collection on a
single large tree.  I have a multiple graft tree for my own enjoyment, but I
also have the important varieties on individual stocks if I share scionwood.
And there ARE signs of virus in my big tree - apple mosaic and burr knots -
which don't show up on the individual trees.  I destroy all the wood from
the big tree. 
-Lon Rombough 
    
Grapes, writing, consulting, my book, The Grape Grower, at
http://www.bunchgrapes.com

From: list at ginda.us
Reply-To: North American Fruit Explorers <nafex at lists.ibiblio.org>
Date: Wed, 16 Apr 2003 22:38:29 -0400
To: North American Fruit Explorers <nafex at lists.ibiblio.org>
Subject: Re: [NAFEX] multiple apple cultivars on one tree?


I grafted a bunch of varieties onto two crab apples.  One of them had
some leaves that were oddly shaped after that.  It may have had them
before I grafted for all I know - I hadn't looked at it too closely.
But I did worry if I might have given it a virus.  Two years ago we had
a serious summer drought, and that tree nearly died.  It finished dying
last year (in more dry weather, although I watered it.)  The other crab
did fine, and I haven't seen any other dead or dying apples around
town.  So I think it's likely that something from the multiple grafts
weakened the crab.   Whether that was a virus, or some kind of
incompatibility, or just that there were "holes" in its skin where the
grafts hadn't fully healed, I couldn't say.  I do know that if I'd just
pruned it and not put on the extra wood, it would have been minor
pruning.  (That is, I didn't chop off much of the tree to graft it.)

I was very careful to graft each type of scion onto only one of the two
crabs, and to wash all my tools carefully between trees.  So a virus
transmitted to one would likely have missed the other.

The other crab is looking very happy right now, with 5 different
cultivars grafted to it.  Interestingly, the crab twigs have tiny
leaves showing, and the grafted twigs just have swelling buds.  I don't
know if that's because the crab is naturally earlier or if its because
of some compatibility thing.  But some of the grafts look like they
might flwoer this year, which would be very exciting for me.


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