El Paso herald. (El Paso, Tex.) 1901-1931, 1916-01-06
Pear Blight Cause Not Definitely Known
But Its Presence Is Menace To Orchards
Destroyed Affected
the Disease Still Present; Authorities Causes Are Quoted
By R A FomgC Park Cmusi

IN The Ell Paso Herald OF January 4,
an article appeared stating that
i pear blight is here and that there
is no doubt Of the identity Of the
disease. as it has been fully deter
mind nv state college experts and the
United States agricultural department
There is no reason why this may
not be the case, although IN many sec
lions other conditions have been mis-
taken for the blight. such as sour sap,
die back, or where a pear branch be
comes blackened from any other cause
Real Cause Not known.
The real cause of pear blight and
lust how the disease is transmitted
fror, one tree 10 another have never
full treatment by outward application
has been found, or is likely to ever
prove effective. The disease is eyi-
IDENTIFY q poisoning OF the sap and not
susceptible to outward applications.
1t is evident, however, that the
disease is transmitted from branch to
branch and tree to tree. by insects
either feeding on the bloom or sucking
the sap. and this poison is thus carried
from tree to tree and from one location
10 other locations
According to Downing, recognized
authority on English horticulture, the
frozen sap blight OF the Americans
may be the starting Of all the trouble.
The circumstances under which this
disease is apt to occur are given Dy
Downing as: a very sudden and early
winter, succeeding a damp and warm
autumn. and similar conditions where
trees are kept growing in vigorous
condition by late irrigation The trees
are forced into a vigorous second
growth. which continues late, while
the sap vessels are still filled with
their fluids: q sharp frost takes place
and is followed in the day by a bright
sun By suddenly freezing and thaw-
a If
loses its vitality and becomes dark
and discolored-
In the ensuing spring the upward
current of sap rises through its ordi-
leaves expand, and for some time, near
" all the upward current being taken
up to form leaves and new shoots, the
tree appears flourishing. Toward the
beginning Of summer. however, the
leaves commence sending the down
ward current Of sap to increase the
woody matter OF the stem This cur
rent has to pass downward through
mains portions of the poisonous sap.
which had been arrested in its course
the previous autumn. This poison is
diluted and is taken up by the new
downward current. distributed toward
the pith and along the new layers OF
alburlum. thus tainting all the neigh
boring parts
When Branches Turn Black.
Should any Of the adjacent sap YES
sells have been ruptured by frost. so
that the poison thus becomes mixed
with the still ascending current Of sap,
the branch above it Immediately turns
black and dies. precisely as If poison
were introduced under the bark, and
very frequently il is accompanied with
precisely the odor Of decaying, frost
bitten vegetation.
Mr. Downing also observes that, II
poison becomes largely diffused, the
NIL ~ ina 4 In DO Ff7=
two; but that if 1t is only slightly
present. the tree may recover.
AS this disease is mainly owing TO
vicissitudes OF climate. over which,
regards a pear orchard. We can have
little control. care should be taken 10
use preventive means.
Encourage Growth Of shoots.
The growth of shoots should be en-