The Republican. [volume] (Oakland, Md.) 1877-current, 1915-11-04

ease can prevent renewed attacks upon
our trees; consequently, it is advisable
to put forth a vigorous effort to bring
the disease under control. It has been
demonstrated in other States that
blight can be controlled, and that it is
feasible and practical to control it.
However, it is necessary for the orch.
ardist to have an accurate knowledge
of the essential facts concerning the
cause, spread and control of the dis.
ease.
Spread OF Blight
Blight is caused by a microscopic
germ which lives in the tissues of the
tree. 1t lives over winter in those In
fected parts of the tree that do not dry
out. As long as they remain moist
the organism can live, but if they dry
out at any time the germ dies. Those
parts that carry it over winter are
called "hOld-over cankers." Only a
relatively small number Of the cank-
ers are hold-over cankers, because the
dead bark of the canker often breaks
away from the living bark, thus cut.
ting the supply of sap off from the
canker In such cases the canker
readily dries out and the germs die.
This is more common in apples than
In pears, for pears are usually more
susceptible to the disease than apples;
and, too, the diseased bark of pears
does not break away from the healthy
bark as readily as in apples. Hold
over cankers are, therefore, more com
mon in pear trees than in apple trees.
For this reason a few old pear trees
very often constitute the source of in.
lection for adjacent orchards.
From the hold-over cankers in the
spring a yellowish, sappy substance
oozes out through the bark. This sub
stance contains countless numbers of
the germs, 1t is visited by flies and
other insects, some of which later
visit the flowers and tender twigs,
leaving the germs on whatever they
happen to come in contact with. By
this means, the germs are carried to
the nectar in the flowers where they
increase in number very rapidly, so
that bees visiting these infected flow
ers get the germs on their mouth parts
and their feet and carry them from
flower to flower dropping the germs
wherever they happen to alight, In
few days the disease can thus be
widely spread in an orchard, although
It may have been confined to a very
few hold-over cankers a week before.
It Is the hold-over cases then that be-
come of prime importance in the dis
tribution of the disease.
Control OF Blight.
All cases of hold-over blight must be
cut out Of all pomaceous trees in the
orchard and in the immediate vicinity
between late summer and the begin
ming of growth the following spring.
This includes practically all infected
parts Of pear and ounce trees, and all
cankers and branches that have not
previously dried out Of the apple, crab
apple, service berry, hawthorn and
mountain ash, both cultivated and
wild. A canker is treated by cutting
OUT all CQe du6CCeQ DARK WlJn KNIFE
and gouge, or it may be removed by
cutting off the branch just below the
canker. In those cases where the
whole branch has died, the branch
should be removed few inches below
the diseased tissue. In spring and
summer the tender sprouts from the
trunk and larger branches can be
shipped off best with the fingers with
out danger of reinfection. The tools
used and the wounds made, must al
ways be sterilized after treating every
case to prevent reinfection. This is
done by wiping them with cloth or
sponge wet with the sterilizing solu-
ton which is carried in bottle in the
pocket.
In addition to the above, wherever
blight has been severe, 1t is not ad-
visable to use fertilizers or practice
summer tillage and winter pruning,
for anything that stimulates rapid or
prolonged growth tends to make the
tree more susceptible to the attack Of
hituhA