North American Fruit Explorers mailing list at ibiblio

[Alan Haigh <alandhaigh@gmail.com>]

A few years ago I wrote an article for NAFEX about grafting to create tiers
by having 2 or 3 different varieties making up the trunk of a central
leader with each successive tier being a different variety.  This is a
pretty stable way to have up to 3 varieties on the same tree- especially if
you graft less vigorous varieties as you build upwards.  It actually makes
it easier to maintain as a central leader than when it's of one variety
because upper tiers will always eventually outgrow lower tiers- even with
summer pruning, I think.

At any rate, if the upper tiers are less vigorous it's easier to maintain
that Christmas tree shape.   Generally, sustaining a central leader tree
requires cycling the branches of the upper tiers when their diameter gets
close to the diameter of branches below.  No matter what you do during
summer, diameter regulates the flow of sap and that water and N. has to
have its affect.  Try to keep that thick branch small and get watery fruit,
is my theory.   A branches diameter determines how much secondary wood and
room it needs for balancing vigor.

In my variety by tier method every successive tier starts as a vigorous
water sprout attached to the trunk just above the lower tier that I do a
simple splice graft on.  Once it's established the trunk above the graft is
removed and the new scion becomes the trunk.

Someone mentioned that it might be useful to also avoid having higher tiers
grafted to varieties that will drop fruit on lower fruit before it's
harvested, but on same variety trees I've never had fruit that much damaged
by dropping fruit from above, even though most varieties have a pretty wide
spread of ripening time.

On the subject of summer pruning kiwis, my argutas seem to need  more than
two clippings to keep the light on fruiting wood and keep them in-bounds.
Maybe I start pruning them too soon  or my soil too rich but I wind up
hedging them 4 times every season and they still keep on growing vigorously
to the bitter end.