[NAFEX] Cold Hardiness in Peaches

Dennis Norton dmnorton at royaloakfarmorchard.com
Mon Jan 2 14:03:31 EST 2006


Jim,

Paul Friday at http://flaminfury.com may be a good person to assist with 
this quandary.  He has done quite a bit of experimentation with cold 
hardiness in peaches.

Dennis Norton
Royal Oak Farm Orchard
http://www.royaloakfarmorchard.com


----- Original Message ----- 
From: "Jim Fruth" <jfruth at uslink.net>
To: <nafex at lists.ibiblio.org>
Sent: Monday, January 02, 2006 8:41 AM
Subject: [NAFEX] Cold Hardiness in Peaches


    Bernie answered why his apple trees die while mine thrive in that his
climate has a longer sustained low temperature than my climate.  Some months
ago, Dave Griffin wrote about his zone 3 peach tree experiment having
noticed that the boles fail to harden off in time for Winter.  I see both
conditions happening in my (zone 3) peach orchard and suspect that, while
the above two conditions contribute to the demise of some of my trees, there
seems to be another, unidentified, factor at play.
    First, to answer Dennis Norton's concern about excessive nitrogen
applications in Fall, the nitrogen I apply is never excessive - I follow my
soil testers recommendations.  Secondly, I apply fertilizer ONLY AFTER
dormancy has occurred.  Also, I ALWAYS drastically thin the peach crop
allowing no two fruits to be closer than 4" apart and not more than 3 per
branch.  Dennis also asked about age; after last Winter's -38° F I've only
got one tree left that is over five years old.  It did get beat up a bit in
that upper ends of branches died back.  Worth mentioning is that it was
genetically different from all others in that part of its fruit were
(typically) borne on spurs whereas fruit on all others were borne only on
new wood.
    Before last year's big freeze, only some tree deaths could be attributed
to non-hardening off.  Most often winterkill occurred in the crown among
branch ends.  Sometimes trunk (bole) death occurred (characterized by Spring
crown growth that soon withered).  Occasionally, trunks would winterkill
down to the snowline sprouting from below that point the following Spring.
Whenever trunk death occurred, trees re-sprouted from the roots.  About a
third of the time, though, trees would winterkill(?) and not sprout from the
roots.
    So, from my observations, while sustained low temperatures and failure
to harden off are two factors that contribute to the demise of peach trees,
there's got to be one, or more, other factors.  What might they be?
-- 

Jim Fruth
Brambleberry Farm
Pequot Lakes, MN
www.bberryfarm.com
Jams, Jellies and Syrups

I have never heard of peach trees withstanding fairly colder temperatures
than about -12?F; however, hardiness is also affected by the preconditioning
the trees receive before being exposed to winter temperatures. How old are
the trees when they die off?

I know you mentioned hardening off is not a factor, but if the tree is late
in going into dormancy it will be more susceptible to cold winter
temperatures. I notice that you fertilize some of your crops in the fall.
Excessive levels of nitrogen fertilizers in late summer or fall can delay
the onset of dormancy and increase the tree's susceptibility to winter cold
injury.

If a tree is cropped too heavily, especially in late summer, its reserves
are depleted and the tree may be susceptible to winter injury.  These are
all factors that may or may not exist in both your and Bernie's situation.

Dennis Norton
Royal Oak Farm Orchard








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