North American Fruit Explorers mailing list at ibiblio

[Douglas Woodard <dwoodard@becon.org>]

I don't think the implication was in my post, though I wondered if the
reason for the low budding that Sarah mentioned in the local course she
took was partly to protect the union from cold.

While I don't have enough personal experience, I have read from several
sources that graft unions are more vulnerable to cold than either stock
or scion. This may be limited to the early years, or especially in the
early years. My guess is that keeping the union low near the ground
surface (and possibly under the snow) will protect it. Getting it
underground on transplanting might protect it more. Scion rooting could
then be expected eventually.

If one were not worried about preserving the effect of a dwarfing
rootstock then scion rooting probably would not be a problem and might
be a benefit since there seems to be at least a little difficulty with
translocation of nutrients across most graft unions, or at least that is 
how I interpret the data from the small number of studies on this topic 
I have read. I am *guessing* that if the root makes a contribution to 
plant vigour, then the original root would be maintained, scion rooting 
would not take over entirely, and would not result in a decrease in the 
vigour of the whole plant.

For new members, use of a nurse root, which may not be fully compatible 
long term but will support the scion long enough for scion rooting to 
take place if the union is buried on transplanting, is a well known 
technique.

David, Sarah mentioned that she had mistakenly placed Corn Hill Nursery 
(near Petitcodiac, New Brunswick) in Nova Scotia in her original post.
It was from Corn Hill that she had bought her trees.

Doug Woodard
St. Catharines, Ontario, Canada



david.maxwell@dal.ca wrote:
> Do I sense in Doug's reponse an implication that on frost-tender rootstocks (eg. M-9), 
> budding (or grafting) low, (presumably with a frost-hardy variety), will reduce the risk of 
> winter-kill?  
>
> You are correct that hardiness is not a particular problem here in Nova Scotia, (zone 5), and I 
> have never had any cold damage to my trees.  But if the problem is cold-hardiness, then it 
> seems to me the solution has more to do with the rootstock chosen than the height at which it 
> is budded.  (Use something like Antonovka or Ottawa 3 rather than the Malling series).  Most 
> of my trees are (now) on O-3, and are grafted at least a foot up from ground level.  
>
> (Sarah, I am intrigued that somebody in NS is selling trees; I was unaware that anybody was 
> doing so.  Could you perhaps tell me (off list if you prefer) where you got your trees?)  
>
> David Maxwell in balmy South Shore Nova Scotia, zone 5. (Temperature today
> 34 degrees F, 
> and no sign of bud break.)
>
> > Sarah, that Nova Scotia nursery may have been concerned mostly with the
> > convenience of the people doing the budding, especially as it affects 
> > their productivity. It may be that most of their clientele (if in Nova
> > Scotia, especially if commercial growers in the Annapolis Valley) is not
> > much concerned with hardiness.
> >
> > Also, if the trees concerned were apples on dwarfing rootstocks, they 
> > would want to avoid scion rooting. On the other hand if you are 
> > propagating on "standard" sized stocks probably you don't care about 
> > scion rooting or you may prefer it.
> >
> > Doug Woodard
> > St. Catharines, Ontario, canada
> >
> >
> > Sarah Kehler Ewing wrote:
> > > I'm wondering if anyone would care to share their insight into the
> reason they graft at a chosen height.  
> > > When I took my grafting classes, we bud grafted just above the
> original level of the dirt so that the graft union would be just above the
> ground when the rootstock was planted out in the field.  However, I've
> bought fruit trees from a nursery in Nova Scotia and their trees were
> budded a good 8" up the trunk! 
> > > Thanks,
> > >
> > > Sarah
> > > zone 3 (can be -40F with no snow cover)
> > > Edmonton, AB