The Topeka state journal. [volume] (Topeka, Kansas) 1892-1980, 1915-12-04

or vital layer between the wood and
bark is killed, death of that particular
area, of course, results.
Spraying Not Successful.
For various reasons spraying has
not been practically successful in con-
| trolling the disease. The eradication
method. or actually cutting out the
| diseased area, is the principal way of
controlling pear blight. Other meth
DDS, such as withholding stable man
ure and heterogeneous fertilizers, mod
crate cultivation or Withholding it
completely, seeding the orchard down
to grass or clover, or sowing rank
growing cover crops after the blight
/ appears in the spring, such as cow
peas and sorghum in the middle
states, oats, millet, or similar crops in
/ the northern states, all help in a sec
ondary way in reducing the severity
of the blight. In the irrigated ORCH
ards the use of the minimum amount
of irrigation water is also advisable.
Direct Eradication.
The main method of controlling
pear blight, however, consists in cut
ting out the diseased tissue wherever
found and disinfecting the wound and
the instruments to avoid spreading the
disease. In the great majority of cases
fortunately the blight comes to a def
mite standstill in the bark, after killing
certain distance, and stops. The
{
crack or crevice forms between the
live and the dead bark, and the case
ends itself naturally and heals out.
In many cases, however, the disease,
while dying out in the older parts
keeps on spreading on the margin, the
germs renewing themselves by null
tiplication and injecting new areas of
fresh bark. When they manage to
live through the dry, hot summer
weather and keep alive until autumn,
when the leaves drop from the trees,
they almost invariably live over win
ter, and though greatly checked by the
killed or apparently even injured by
the cold.
Flies Infect Blossoms
Such cases become holdover blight
and by this means the supply of
germs is kept over in the orchard for
the next season. The holdover blight
cases may extend considerably and
result in further damage to the tree
by the extension of that particular
area, but their worst feature comes
from the fact that they supply the
gummy eXudate and the virus for new
infections on the blossoms the follow
ing spring. When warm weather
comes in the spring and root pressure
fills the tree with sap the holdover
cases start off vigorously and exude
the gummy matter, especially in moist
weather, literally teeming with the
pear-blight bacilli. Insects, many
SONS.
Cutting out pear blight, therefore,
has a double purpose, first of stopping
the blight and cleaning up the tree,
and second of preventing the hold
over. Much good work on blight can
be done in the summer time, but the
final cleanup shoul occur in the fall
Summer cutting, beginning as soon as
the blossom blight shows plainly and
continuing until the fruit is about half
grown, is helpful. The best time to
do it is in periods of dry, sunny wealth
er. On young trees il is often very
and apple trees, to head off the blight
by cutting well below it as soon as IL
shows up in the spring and summer.
Examine Bark Thoroughly.
In all blight cutting, either summer
or autumn. it is important to examine
thoroughly by cutting off the bark
around the lower edge of the infec-
ton to determine the lowest point at
which any change of color, even a
water-soaked or transparent condition,
can be detected with the eye. Young
or active blight on the lower margin
is readily distinguished by its moist,
water-soaked or usually reddish dis
celebration of the bark. This is in
rather marked contrast with the dry,
dead bark where the germs have died
out Having found the lowest margin
Of the disease, if it is on a limb, the
knife, pruning shears, or saw is used,
cutting well below the Infection If
the disease has stopped and the dead,
dry bark is sharply defined in contrast
with the live portion, the cut may be
made quite close below the margin,
or it may be made where any con-
venient branch energies or where the
limb leaves the main branch or the
trunk.
If the freshly blighted area is short
and the blend is rather abrupt between
the dead and live portion, the cut may
also be made rather close to the dis
eased area if required by the nature
of the branch. Six inches may be suf- |
ficient in such cases, but the cut
should always be made onto sound |
bark and wood. If the saw is used it |
the edges of the bark and the surfaces
of the saw cut on the wood with a !
sharp knife to see if the whole surface |
iS normal. If a water-soaked appear |
ance is found on the surface of the !
wood, this indicates that the germs !
have penetrated the woody vessels /
and a lower cut is necessary, repeat /
ing the same process.
If the disease has run into the bark /
of a larger branch or extended down !
on to the body, the bark should be j
removed from this area,
and four 20 six inches or even more
at the bottom, according to the viru-
lence of the case, as suggested for /
work on the branches.
A large bladed pocketknife, a scra-
per, and a three-fourths inch carpen-
ter's gouge. kept well sharpened. are /
useful in cutting out the bark on !.
these areas. The same principles of ,
looking for water-soaked areas in the
wood should be applied here, and the
gouge, or perhaps the chisel, used to 4
remove all suspicious wood and bark.