Evening star., 1939-03-23

bNVtSOOVA VI SSueuSS'u IVY uSSS
In Field, Laboratory
And Study
BY Thomas r. Henry.
New tree diseases-their spread favored
by automobile and air trafac-are . con-
stantly increasing menace to American
forests, DR.. g. F. Gravatt, Department
Of Agriculture botanist, warned mem
bers Of the Botanical Society Of WASH
ington the other night.
The ravages of the chestnut blight,
which has practically eliminated chest
nuts in the Appalachian region, are well
known and much publicity has been
given to the Dutch elm disease in the
last few years. Less attention is paid to
more obscure maladies of the forests
which do not kill outright. There is a
new root rot Of chestnuts, new persim-
mon wilt, bark disease affecting
beeches and a recently identified virus
disease Of elms.
The persimmon wilt, Mr.. Gravatt said,
is OF particular concern. It has become
established especially In Tennessee and
Florida, but has not yet spread to the
few remaining persimmons around the
District of Columbia. Pathologists study
ing the infection are by no means conf
dent that they can stop it before 1t de-
stroys tree celebrated in American folk
lore. Chinese and Japanese persimmons
seems to be resistant and it may be DOS
sible to introduce them into the South
eastern United States.
The persimmon, which hangs on the
tree late and is often available when
other foods are covered with snow, is a
valuable source Of food for birds, opos-
sums, skunks, foxes and deer.
The white pine is. subject to q rust
which can be eliminated only by erad-
icating wild currant and gooseberry
bushes. These also are important sources
of food for wild ufe Some species of
willows are being killed by . combina-
ton OF two diseases, one from Europe
and the other from Asia. The willow
also Is valuable source of food for
game.
I'VE are all very much disturbed" said
Mr.. Gravatt, "at the rapid rate at which
new destructive tree diseases are appear
Ing IN this country. We are faced with
increases in international commerce, in
automobile travel north and south in
America, and in airplane transport all
over the world. The introduction of dis
eases into the country and their spread
are thus greatly facilitated. Any predic-
ton for the future would be only specu-
lative. It is probable, however, that thus
far our forests have been exposed to rela-
lively few Of the potential tree disease
organisms present on other continents. !"
A large proportion of deafness in
adults is due to overgrowth of gland
like tissue in the nasopharynx-the
pharynx just above the soft palate. ac-
cording to a report just made to the
American Medical Association by Drs.
S. j. Grove and John w. Baylor of
Baltimore.
It would be possible, they claim, to
reduce deafness In half in a generation
by following out the implications Of this
theory. School children, they hold,
should be examined at least once q year
and those with such an overgrowth
should be treated by x-rays.
THE abnormal growth OF such tissue"
they report, partially obstructs the
Eustacian tubes, causes an oversecretion
Of mucous and produces a chronic irri-
tation in the tubes and middle ears.
Hearing of the middle tones becomes
impaired but children at first may have
no evident difficulty in school or at home.
If they do it is ascribed to inattention.
III this overgrowth of tissue is allowed
to go untreated the deafness progresses
by involving one octave after another
towards the low end of the scale and
becomes evident only when the tones of
the speech range are affected. Thus
the primary cause may be insidiously
damaging for several years before 1t is
recognized"
The location Of these enlarged tissues,
the two doctors say, makes it impossible
to remove them surgically without doing
more hurt than good. Safe doses Of
X-rays or radium do not destroy or
totally remove them but reduce them in
size and temporarily inhibit their growth.
The most common result Of neglect, they
say. is an insidious, slowly progressing
deafness that begins with the highest
tones. Recurring attacks of Inflammation
OF the middle ear constitute the second
most frequent symptom. A third is long
continued discharge from the ear. The
growth is stimulated by every slight in
lection in children. 1t ceases at puberty
but the damage already has been done.