North American Fruit Explorers mailing list at ibiblio

["woodard214" <dwoodard@becon.org>]

Tree nutrition is important in fireblight susceptibility. 
Fertilization with nitrogen wherever the tree roots can reach it, is 
extremely dangerous for the susceptible cultivars. I have seen a row 
of Bartletts badly damaged because a patch of sweetcorn was planted 
nearby and fertilized with nitrogen.

I have also seen several Sheldon trees which were topworked to Bosc, 
ruined after they were fertilized with nitrogen. Sheldon is quite 
susceptible to fireblight, even more than Bosc. 

I was told in 1983 by a local grower that work done at the Geneva 
station (New York) had shown that high calcium and potassium improved 
resistance to fireblight. Growing in sod increases soil potassium; 
straw mulch even more.Growing in sod has long been known to decrease 
the susceptibility of pears to fireblight.

Wounds and secondary blossom provide entry points. Pruning tools 
readily carry the infection in the growing season. There a a lot of 
variables.

Doug Woodard
St. Catharines, Ontario, Canada


--- In nafex@y..., Don Yellman <dyellman@e...> wrote:
> Doug:
> 
>     I planted a little Flemish Beauty from Mellinger's in '83, and 
it
> grew up into a nice tree by '89, at which time it suffered an 
attack of
> fireblight.  The blight returned in the summer of '90, and there 
was so
> little tree left that I took it out.  (In the very same spot I later
> planted a Shinseiki, which is extremely healthy).
> 
>    Nothing daunted, I planted another Flemish Beauty, also from
> Mellinger's, in '91, and as of this writing it is healthy as a 
horse.
> This tree has never shown the slightest sign of fireblight or any 
other
> disease, and in '98 it started to produce the most delicious pears 
that
> I have ever eaten.  It is now quite a large tree, and I am pruning 
to
> keep it down below 15 feet.  This past summer's crop was, 
unfortunately,
> taken by a late freeze.  The tree is sited in one of my best spots, 
with
> all-day sun and good air circulation.  But I am, after all, on the 
zone
> 6/7 border, and summers here can be brutally humid.  Nevertheless, 
the
> tree is entering its 12th healthy year.
> 
>     Now you may say : "Just wait, Don Yellman, fireblight will
> getcha.......", and you may be right.  But I also wonder whether
> individual trees of the same cultivar might occasionally show some
> fireblight resistance that is not shared by all.  It's not that I 
don't
> have fireblight around.  I had a moderately severe attack on a 3-
year E.
> Spitzenberg this summer, and some obvious fireblight on two mature
> Braeburns.  Dr. Tom Burford advised me to just take them out, but I 
am
> still dithering about it, wondering whether they might be saved by
> careful pruning.  Probably not.
> 
>     So, while the fireblight may catch up with my Flemish Beauty
> someday, in the meantime this tree produces the absolutely juciest,
> tartly-delicious pears that anyone can imagine.  Of course, my 
little
> Magness tree is not yet in production, and I have never had the
> privilege of eating a Warren.  They would have to be pretty good to 
beat
> the F.B.
> 
>     There is lots of scionwood available on this tree right now if
> anyone is interested in grafting.  Just name your caliper and I've 
got
> it.
> 
> 
> Best Rgds, Don Yellman, Great Falls, VA


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