Sharp County record., 1880-11-04
Blight of Fruit Trees.

Prof. T. J. BurriIl of the Illinois In
dustrial University, read paper be-
fore Section B, of the Association for
the Advancement of Science, on the
"Anthrax of Fruit Trees" The wide
spread and disastrous disease of the
pear tree commonly known as fire
blight, and that no less prevalent one
known az twig-blight of the apple-tree,
are due to the same agency. They are
identical in origin, and as similar in
pathological characteristics as are the
trees themselves. The ounce, Lom-
hardy poplar, American aspen and some
other trees suffer from the same or sim
liar affections.
The immediate cause of the disease is
living organism which produces buty-
ric fermentation of the material stored
in the cells, especially those of the
liber. This organism is allied to, if not
specifically identical with, the butyric
vibrione Of Pasteur, the Bacillus amy
lobracter of Van Tieghem. After re-
counting the history of the disease in this
country, which goes back at least cen
turv, the experiments which were made
with the specific poison or ferment, in
inoculating healthy trees and IN other
Uavs, were recounted in detail.
After it was determined that Spe-
ciic living organism, the Bacillus named
above, was always present in the llber-
cells of the affected trees or branches,
an isolated acre of ground upon which
there were ninety-four pear trees OF
different ages and varieties was selected
for the experiments. The method OF
experiment was to cut of fsmall portions
Of the bark of diseased trees and insert
them beneath the bark of other healthy
trees, as in the ordinary process OF
budding. The results of these expcr-
iments are given iu table, which
shows that very large percentage of the
experiments were perfectly successful
in communicating the blight from the
diseased tree to the previously healthy
one. Sixty-three per cent. OF all the
pear-trees thus inocuated became dis
eased. Of the peartreeS that were
inoculated from the virus from diseased
pear-trees, ffty-four per cent. became
affected. Of those pear-treeS lnocu-
lated from blighting apple-trees seventy
three per cent. received the disease.
When the poison was taken from the
pear-trees to inoculate apple-treeS the
percentage of successful operations was
much below that obtained when the
process was reversed, probably because
IFhe apple-tree is the more hardy of the
two. The virus seems to be quite harm
less when it is applied to the epidermal
surface of the leaves of a tree; it does
not seem to enter through the Stomata.
OF the entire number OF recorded OBJ
servations, 24.7S per cent. were sue
cessiul, while of the whole number of
inoculations with the knife, 52.O7 per
cent. were effective.
The organism to which the disease is
attributed is so minute that a very great
magnifying power is necessary to enable
one to study it or to make out its form.
1t assumes various shapes during its de-
velopment, and these different forms
may usually be seen at one view in the
microscope. The most characteristic
form is that of two oblong joints with
rounded ends. Their transverse dame
ter is about .0O2 millimetres, and the
length of each joint about .OO3. They
are comparatively thicker and shorter
than the common Bacterian termo, and
they move less rapidly. If this should
prove to be the organism which is the
well-known agent in converting starch,
sugar, ETC., into butyric acid, hydrogen,
and carbon dioxide, this would not in
validate the assumption that it is the
cause of this disease, but it might rem
der the discovery of remedial treatment
less hopeful The most conspicuous
change in the tissues of the affected
plants revealed by the microscope is
the almost total disappearance Ofstarch
/ +bn calls