The Manitowoc pilot. [volume] (Manitowoc, Wis.) 1859-1932, 1902-07-24
TO PREVENT
APPLE BLIGHT.
important Paper Sent Out From
Madison.
BY AGRICULTURAL DEPARTMENT
Valuable information for the Farmers
WHO ARE TROUBLED WITH PEST
How the Blight Is Distributed AMI
its RamificatiOns II Left
Unchecked.

Numerous inquiries have recently
been received at the agricultural
station, Madison regarding injury to
apple and pear trees. Affected twigs
have usually been enclosed which were
black and shriveled, the attached leaves
being Drowned as if by fire. The in
jury in every case was caused by
blight"
What is blight The disease known
as blight" pear blight" and fire
blight" is contagious bacterial disease
attacking the apple, pear. ounce and
allied fruits. 1t frequently attacks the
wild crab and is occasionally found on
the Mountain Ash.
What it does. Blight assumes two
different modes of attack known as
twig blight and blossom blight the
cause of the two being the same. In
the former the new shoots, growth of
the current season, are affected; in the
latter the blossoms and fruit spurs are
destroyed and commonly a portion of
the adjoining main branches.
The conditions that favor blight. A
wet season favors blight dry season
hinders it; a dry season entirely checks
it. The blight microbe soon perishes
when exposed to drying conditions.
Unfortunately, conditions that favor
growth of the tree favor blight Heavy
pruning during the dormant period in
duces strong growth of the new wood
and favors the development of the
blight germ. Trees heavily manured
with barnyard manure are apt to be
more affected than those not 80 well
fed Trees that are we'll cultivated
often blight more than those growing in
sod.
How distributed Blossom blight is
undoubtedly distributed by bees and
other insects that collect honey and
pollen. The blight germs find lodg-
ment in the rootary where they multi
ply rapidly and are carried from tree to
tree at blossoming time. The blight
microbes are held together by "a sticky
substance and are not therefore readily
disseminated by the wind. In the case
of twig blight they presumably remain
within the affected tissues until set free
by some agency that ruptures the bark
The mode of infection in this form of
the disease is not we'll understood but
presumably occurs through the agency
of insects. Several species of minute
insects inhabit the terminal buds of
growing shoots.
Remedies. AS the blight organism
works wholly in the inner tissues OF the
plant, it is not possible to control it by
spraying. The only remedy, at present
known, is to remove and destroy, by
burning, the affected twigs. As the
blight does not, presumably, live over
winter in the ground, it may be checked
if not eradicated by this method.
Usually the blight progresses most
rapidly during the period of most rapid
growth Of the trees and generally stops
at the end of the growing season. At
this time there il usually distinct line
of separation between the live and dead
wood. All parts below this line are
healthy and may be preserved In
some cases, however, especially those
that appear late in the season, the line
of demarcation is not distinct and the
field of injury blends gradually with
that of uninjured bark. 1t is probably
that the blight is carried over winter by
these cases as the germs are not sus-
ceptible to cold and receive sufficient
moisture for their maintenance from
the sap Of the tree. 1t is essential then
to exercise great care in cutting to re
move these cases OF "hold-over" blight.
In removing blighted twigs it is ad-
visable to cut far enough back to insure
the removal of all affected tissues. The
removal for six inches of sound wood
below the line of separation is not too
much. This work is best done in the
fall before the leaves have fallen as the
blighted twigs may then be more
readily observed. The shears or other
cutting instruments should be dipped
frequently in an antiseptic solution to
guard against transferring the disease to
uninfected branches. A five per cent
solution of normalin will answer the
purpose A cloth moistened with this
may be carried and used to wipe the
shears In the case of blossom blight
on old trees nothing of value can bt