The Wilmington morning star., 1940-02-19
POTATO GROWERS
FACE new MENACE
Presence Of Bacterial Ring
Rot Reported BY Patho-
logist Garris

There's more trouble ahead for the
Irish potato growers of North Caro-.
lima, says Howard r. Garriss, as
sistant Extension plant pa~thologist
OF State college. The latest menace
is a new bacterial wilt. disease
which is being called Bacterial
Ring Rot" in the 26 states where
the disease has been reported.
although this disease has not
become widespread in North Caro-
lima, the sooner we learn about it's
symptoms, cures, ETC., the better we
will be-" Garriss declared. "The
chief way the disease is spread is
through seed stock, and because Tar
Heel farmers annually import a
large part of their seed potatoes,
especially in the commercial areas,
there is a strong chance that grow
ers in this state will experience the
disastrous losses suffered in other
areas unless they take steps to pre-.
vent and control the disease"
Here is what the State college
specialist knows about the disease:
1t is caused by a germ which at.
tacks the vascular ring OF tubers
and causes a grayish to prownish
d~iscoloration of the ring. This is
often followed by soft rot, with a
final loss of the whole tuber. In less
serious cases of infection, the germs
may be present in the tuber for a
long period Of time without any
noticeable symptoms.
Explains Symptoms In Field
In the field, the top symptoms are
best detected from 80 to 80 days
after planting, or just before the
tops begin to die. A rather sudden
whiting of the tops takes place with
final browning and drying. When
the tops become seriously diseased,
they frequently fall over and the
basal parts may turn black. some.
what similar to black leg symptoms.
The evidence to date indicates
that the disease does not live over
in the soil from year to year, except
possibly in volunteer potatoes. How
ever, it may live over in certain sol
types. The main way in which the
organism is spread is through the
seed stock. Seed-producing areas
are now carrying the blame for the
spread of ring rot to other states
When any of the potatoes in the
seed lot are infected with ring rot
the disease is very rapidly spread
to healthy potatoes by the cutting
knife. For example, it has beer
shown that with as low as one-hal
of per cent of the seed potatoes
infected, the disease can be spread
while cutting to the extent that II
to 20 per cent infection will result
in the field.
Experiments have shown that Il
you cut through a potato with ring
rot, the next ten and sometimes
many nor healthy potatoes cu1
with the same knife will result ir
infected potatoes.
Another way the disease is spread
is by contact of infected seed pieces
with healthy ones during the pro
cess of planting.
Advice On Control Given
Now for some advice from Garriss
on how the disease can be kept Out
of North Carolina to any large ex
tent, and how it can be controlled
when and if it does occur:
l.. If possible, get seed from a 10
cality that is free from the rot.
2. Buy seed from a state that has g
good certification system. CThe of
flee of the Extension Plant Patholo
gist at State college will gladly fur
nish the latest available information
to growers on d~isease-free areas an6
states with good certification sys
tems.)
3. Try to buy seed with a flat
money-back guarantee that they are
not infected with ring rot.
4. Sterilize the knife frequently
when cutting seed by dipping it for
a few seconds in a germicide disin'
fectant solution, Of by dropping ii
into boiling water for a short tine.
5. If you think the. disease is
present, treat the cut seed pieces by
dipping them into a solution of
S~emesan-bel or Mercural (prepared
according to the manufacturers di.
rections) and dry before planting.
6. Discard seed pieces that show
%discolored tissues, because such
pieces indicates a diseased condition.
In conclusion, the Extension spe.
cialist said that it is not his inten-
ton to unduly alarm any Irish po-
tato grower, but merely to warn
him in order that the potato indus.
try may cont; nue. to prosper in
North Carolina and not suffer the
severe detbacks experienced in other
states where Bacterial Ring Rot has
virtually wiped out the crop.
pound is about the story" Mr.