The Wilmington morning star., 1947-03-04
POTATO DISEASE
FOUND in STATE
Internal Cork Discovered
. In Southeastern North
Carolina Counties

The discovery of internal cork,
a new potato disease, in Fender,
Columbus, Wake and Scotland
counties was revealed yesterday
by Howard R. Garriss, extension
plant pathologist of the State Col
lege extension station, Raleigh.
Indications are that the disease
is much more widely spread in
North Carolina, than the prelimi-
nary survey reveals, he stated,
and warned that growers SHOULD
be over careful in the buying of
seeds and plants as the disease is
carried in them.
A survey now being conducted
by the Plant Pathology section of
the State College station in order
to determine how widespread the
disease is in North Carolina, and
is being made in cooperation with
the N. c. Crop Improvement AS
ISOLATION and the Department of
Horticulture.
No traces of the disease have
been discovered in New Hanover
county, R. w. Galphin, county
agent, said yesterday. but he ex-
planned that nc tests have been
made of the sweet potatoes grown
here. Any farmer who detects any
symptoms of the disease on his
plants are advised to notify the
farm agent in order that tests can
be made.
The internal cork disease is
characterized by the formation OF
hard, dark brown spots of irregu-
lar shape and size in the flesh of
sweet potatoes. Externally, the po-
tatoes usually appear to be sound
and the spots cannot be detected
without slicing through the potato.
Experiments indicate that it is
caused by a virus carried in seed
stocks and may be spread from
plant to plant in the field, posi-
bly, by certain insects. The cork
like spots in the potato a often
be detected at harvest time, but
they may increase in size and
shape during storage.
Certain leaf symptoms, especial
ly a purple ring spot, are often
associated with the disease in the
field but the connection with in
ternal cork has not been con-
clusively established.
The survey now under way is
being conducted in order to de-
termine how widespread h G
disease is in North Carolina, and
is being made in cooperation with
the N. c. Crop Improvement As
ISOLATION and the Department oil
Horticulture. Samples of all seed
stocks inspected for certification
in North Carolina this year were
examined for internal cork.
While the disease was found in
only one sample, it was pointed
out that the survey to date has
.sbeen largely confined to these
stocks which have inspected for
ce~rtification. furthermore, in a
field survey last fall, the ring spot
leaf symptom, vas found general
" distributed throughout eastern
North Carolina, it was explained.
In order to guard against the
spread of internal cork and the
introduction from outside sources,
the following suggestions were
made. ,
l. Growers should cut 2 potatoes
from each bushel Of seed stock to
be bedded into "A inch slices. Al
low samples of any slices showing
suspicious internal corky spots to
dry and send to the Plant Path
ology Section, N. c. State College,
for diagnosis.
2. No potatoes from stocks in
which the disease is known Oh
suspected to be present should be
bedded for producing plants.
3. Sweet potatoes should not be
planted in fields in which potatoes
known to have internal cork were
grown last year.
4. No seed stocks or plants
should be brought into North Car
DINA from sources outside the
state unless they are rejected by
qualified authorities arc stated tt
be free from internal cork.