The Hood River glacier. (Hood River, Or.) 1889-1933, 1917-06-07
How to Treat Winter Kill
Leroy Childs--

| Die-back, or so-called winter kill
of apple and pear trees is a common
disorder in many orchards of the val.
ley this Spring The term "die-back'
has been adopted in many sections OF
the country for this trouble and ii
is more appropriate than the old
name of winter KILL" Winter con.
ditions have nothing to do with fully
80 per cent of the trees that have
failed to throw out normal foliage,
and for this reason the term was
very confusing, especially so as it
sounds much like the term winter
injury" Winter injury is a term u.s.
ed for mechanical disorder of the
tree brought about by freezing and
thawing. Our commonest form of
winter injury is manifested in the
form of severe splitting Of the
trunk, usually on the southwest side
of the tree.
Die-back, for the most part, is the
result of mis-treatment of the tree
during Summer and can be prevented
by proper irrigation only. BY irriga-
tion is meant the maintaining of a
uniform moisture condition of the
soil during the growing season of the
treo. Each orchardist must deter
mine the condition of the soil at Ill
tervals during the Summer; different
soils demand different treatment.
This determination can be made on
ly by digging to depth of three or
four feet with shovel or by using
the soil augur at rather close inter-
vals mot to exceed three weeks dur
ing the growing season.)
The cause which produces di.
seased tree suffering from die.back
has not been completely proved from
an experimental standpoint. Obser-
vations of all workers, however,
seem to indicate that it is the burn.
ing off of the root hairs or root feed
ers. Root hairs are the tender wat
cry rootlets-soft and extremely de-
licate-by whose aid the plant draws
food and water from the soil. These
root hairs are very sensitive to heat
and drought and if the soil-even
though it be for few days only
is permitted to become thoroughly
dried out, these small rootlets are
killed, resulting in a tree suffering
from die-back the following Spring.
Increasing soil fertility and ne
glecting the proper irrigation of the
trees will work havoc in our or
chards unless more attention is CIV
en- to the proper use of water By
increasing fertility the number of
root feeders is increased. The tree
responds to this stimulus, forming a
vigorous top which requires much
moisture to maintain in a normal
condition. If this supply of root
feeders is all wiped out at one time,
the tree undergOes tremendous
shock and the Transportation, which
occurs in the portion of the tree
above ground quickly drains the tree
of available moisture and food. Most
trees suffering from die-back make a
slight growth in the Spring. This
feeble start consumes all of the stor-
ed-up food and moisture and as there
are no more root feeders to supply
more food and moisture, growth
stops. The result is that the tree
dies back until it can reorganize it's
feeding system.
There are good many orchards in
the valley which are just on the edge
of a die-back condition. A close OBJ
server can detect this condition by a
few simple warnings given out by
the trees before a serious condition
has been reached. The writer has
observed three which have proven
tn1 snI
worthy of consideration. C) Trees
which have burned badly in the de-
layed dormant spray. (2) Dying and
dropping of the fruit buds (before
the pink stage is reached) on trees
that appear fairly vigorous. (S)
Premature yellowing and dropping of
foliage in early Fall. All of these
indicators could be due to some
other disorder than drought, but as a
general rule drought condition could
be suspected.
We are now more than 10 inches
behind in normal rainfall and for this
reason irrigation should be started
at once, especially in the orchards
that are in cover crops.
This article has been written in
the hope that it might bring to the
grower the serious results that will
continue if irrigation is neglected.
During the past two years this ne.
glect has cost Hood River many
trees and many thousands of dol
lars. Unlike some of our plant di-
seases and insect pests, remedial
measures lie in the hands of the Or
chardist and Of him alone. This re-
medy is the proper use of water.
In the near future the writer will
submit few suggestions for the
handling of trees that have become
so diseased.