The Pascagoula democrat-star. (Pascagoula, Miss.) 1878-1920, 1898-11-25
PEAR BLIGHT.
b. T Galloway, Chief Division Vegetable Physi
0lo-y and Pathology.

B. 7. Galloway, Chief DIVISION Vegetable Physi-
olosy and Pathology.
In the laboratory it has been found
that blight is invariably accompanied
by minute organism, bacillus, alli-
ed TO those which cause such danger
Gus diseases as tuberculosis and ty-
phoid fever in man. These minute
germs have been found in countless
millions in the delicate cells of the
plant, but to prove that they were the
actual cause Of the disease it was
necessary to separate them from the
pear tissues and all other organisms
present, to grow them wholly apart
and in an absolutely pure state, aud
finally to bring them again into con-
tact with healthy pear trees and pro-
duce the disease. This has been done.
The germs OF pear blight, free from
all other organisms, have been made
to grow on pOtatOS. on various kinds
OF gelatin, and other media, just as
the farmer grows a crop Of corn to a
soil free from all other plants. The
germs grow in this way, when picked
into the delicate tissues of young
pear shoot, multiply rapidly, aud in a
few days there is well developed case
OF the disease being thus definitely
determined, it remained to find out
how it was spread from tree to tree,
and how, after seemingly disappearing
in late summer, 1t would break out
again the following spring. The work
was now transferred from the labora.
tory to the orchard itself. Here il
was found that insects, particularly
bees, play an important part dissent
mating the disease. One very dis
tructive form of blight occurs in the
blossoms, and the bees in visiting
these for honey carry the germs tt
healthy flowers. Thus, from one cen
ire a whole orchard may soon be-
come infected, and with what results
will be easily understood by those ia
mliar with the way the blight works
Coming back to blight, the studie:
in the orchard further revealed tht
very important fact that, while tht
branches killed during the summer
usually contain no living germs.after
4 few weeks, in a certain small pro
portion of them, at the point where
the diseased part merges in to the
healthy, they do remain alive, and al
so that these germs pass the winter in
a partly dormant condition. AS soon
as spring opens, the germs in these
few "hold over" cases again start into
active life, and in short time be-
come so numerous that they ooze from
the wood in gummy masses. Insects
are attracted to this more or less
sweetish gum, and by visiting it and
then going to other trees, especially
to blossoms. So much, therefore, for
what has been developed by long and
careful study of this disease. 1t now
remained to apply the knowledge in a
practical way, which was done by
what has come to be done as the win
ter method of combating blight.
They consists simply in acareful in
spection of the orchard in the fall or
early winter and cutting out OF
every branch showing any sign Of the
hold-over blight. Not only is 1t nec-
essary to cut out these branches, but
it is important that they be CON-
pletely destroyed by fire. Following
this practice carefully it has been
found practicable to eradicate blight
no. ouly from the orchard, but also
from the nursery, where the condi-
tions for spreading are much better,
owing to the way the trees are plan