Evening star. [volume] (Washington, D.C.) 1854-1972, 1938-08-20
Fire Blight
Is Menace
Bacterial Infection
Requires Drastic,
Quick Action.

OWNERS Of pear ana apple trees
and ornamental varieties in the
same group, are naturally puzzled
when leaves, branch tips. or heavier
portions of their trees give sudden
evidence OF burning in the midst Of
pleasant, moist weather with plenty
Of rainfall. The withered, blackened
appearance Of the affected parts Of
the tree look as though some wanda.
had touched them with q blow torch
Strangely enough. the real cause
Of this trouble, known as fire blight
has no connection with heat or flame
in spite of the burned effect. Water
which would check and cure heat
injury. only tends to spread and aggra-
vate the condition. Its actual cause
is a bacterial infection Of tiny micro.
organisms invisible to the human eye
of which other varieties cause SO many
of our human aches and pains.
The ease with which this unfor-
tunately common tree infection may
be detected depends on the favorable
or unfavorable conditions under which
it is working. The shriveled, blackened
leaves mentioned above are the most
common symptom, and the most dis
tinguishable. Under favorable con-
ditionS, the bacteria spread so rapidly
that these blackened flags" remain
attached to the twig after the disease
has spread along the branch and down
to the main trunk. Fruit which il
may encounter on the way Is promptly
and thoroughly ruined.
Cankers which are formed when II
attacks limb or trunk may, If allowed
to 60 unchecked, girdle the tree. cut.
ting of the flow of vital sap and killing
the entire organism. AS these cankers
progress, they move from the oozy
stage of active infection to later dis.
coloration and eventual cracking away
of the infected tissue around the edge
of the wound.
Since the moist warm condition,
ideal for rank growth Of the tree are
likewise ideal for growth and spread
Of fire blight, a measure Of contro,
over these conditions Is indicated a.
one way of holding the disease ir
check. Any fertilization which tendi
to encourage the tree in growing ar
excess of tender twigs and water
sprouts, which help spread the bacteria
should be avoided. Pruning should
also be moderate, except for complete
removal Of all water sprouts
This regulation Is really only q help.
ing hand, however, and stronger
practices are necessary when there Il
danger of. fire blight getting a good
hold. Surgical removal of all infected
tissue under the most sterile conditions
is the only sure control method known
to completely remove the infection
Because Of the amount of time and
care necessary to do this work we'll
and there is no use doing 1t at all II
it is not done well, it is not advisable
to enter it unless the tree Is Of sui.
f1cient value to warrant the effort.
Careful, watchful tree owners will
generally be able to detect the disease
as it Is starting, often in the leaves
or outer twigs. They will then be
wise to prune out all visibly infected
tissue, taking care to cut out a margin
of sound appearing growth around the
diseased area where the bacteria may
have taken hold without yet giving
any indication Of their presence. The
tree should then be watched closely
in order to catch any further infection
If it reappears. and to be sure thai
all previously affected parts have beer
removed.