The Greenville journal. [volume] (Greenville, Ohio) 1850-1918, 1917-06-14
AREA COVERED BY ROOTS OF APPLE TREE.

(By LEONARD r. HARTILL, Instructor
in Fruit Growing New York State School
of Agriculture on Long Island, Farm
ingdale, N. "
OF all the diseases of fruit trees
there Is none more dreaded or more
destructive than the disease commonly
known as fire blight. This disease is
of bacterial origin and is extremely
Infectious. 1t attacks the pear the ap-
pie, the ounce, the wild crab apple,
the hawthorn, the mountain ash and
other trees. Owing to its ravages the
commercial growing of choice varieties
of pears is now limited to a cOmpara-
lively small area of the country.
Modes Of Infection.-Under favor
able conditions fire blight may attack
any part of the tree, but usually infec-
tion takes place In the blossoms and
In the actively growing tips of
branches. 1t is brought about by in
sectS, usually bees. The bees visit the
old hOld-Over cankers of the blight and
become covered with the organisms in
their search for nectar. The organ
isms multiply rapidly in the nectar of
the blossoms and enter the living tis-
sues through the unprotected nectaries.
Having entered the tissues they quick
ly blight the blossoms, pass down the
blossom stem into the fruit spur, kill
Ing the tissues and cutting the leaves
off from supply of water, thus pro-
ductng ''fruit-spur blight" the latter
occurring several weeks after blossom
Infection. In serious cases all the
fruit spurs may be blighted In this way
and consequently set no fruit. Some
times the infection ends with the blight
Ing Of the spurs and does not extend
to the twig or branch, but frequently
1t extends into the bark of the branch
at the base of the blighted fruit spur,
resulting in the formation Of typical
blight cankers. Blight cankers are
also originated either through In
fectiOn taking place at the tips
of young, actively growing branches,
particularly If these be water
sprouts, or through wounds of any
kind. Such cankers when on the larger
limbs or trunk may retain active germs
over the dormant season and form the
so-called hOld-over cankers, which
very likely form the only source of in
lection for blossoms In the spring.
Description.-If the infection begins
in flower cluster or at the end of
shoot the leaves will wilt, and in the
case Of the pear, drop. The bark of
an infected tree becomes darkened.
The disease spreads rapidly, running
down the limbs and trunk until the
tree becomes dormant with the ap-
prOach of winter. The following spring
the disease renews its activity. The
progress of the disease is most rapid
in the fieshy outer layers Of the bark.
At first 1t produces watery appear
ance In the affected area, later develop |
Ing dark-colOred, sunken cankers. A |
sticky substance exudes from the can
kers when they are active. This |
substance contains myriads of live
germs.
controI.-The only known remedy
for fire blight is to use the knife and |
saw thoroughly, cutting out all the in
'ected wood: In cutting out blighted
limbs or twigs, cut when possible at
east foot below the infection and
hen examine the cambium below the
:ut to make sure that no blighted por-
ion remains. Large limbs when in
ected should have the infected area
'laned off down to the sap wood. All
Wounds made on a tree In cutting out
Infected wood should be Immediately
washed with solution of corrosive
ublimate Corrosive sublimate one part
o 1000 parts of water). When the
wound Is large 1t should also be paint
d over with good white lead paint.
he tools used in cutting out blighted
VOOd should be kept sterile by being
reQuently immersed In the corrosive
ultimate solution.
During the growing season all trees
q the orchard should be kept under
onstant inspection so that outbreaks
f the disease may be noted at once
nd any blighted wood Immediately re-
loved. In the autumn, in an orchard
here the disease has made it's appear 1
nee, the soil should be removed from ]
round the crowns of the trees and
he trees gOuged at the crowns with a
uarter-round chisel to detect the pres
nee of any blight at the bases of the j..
rees. With large trees the main
mbs should also be gouged at the
)rks.
The most serious development of the
isease is obtained when 1t attacks the t
)Ots of the tree. The usual method of c
rocedure in such a case is to expose f
le roots and cut out all infected por- t
ons, taking the usual precautions of 7
EaalU VIinkaa 4 ~ua..