Iowa state bystander. [volume] (Des Moines, Iowa) 1894-1916, 1914-02-27
POTATO FOOT ROT.
New Disease Of. the Sweet Va
rjety Is Discovered
ht Attacks Primarily the Lower Past
Of Stem From tse Soil Line
70 Four or Five lnchse
Abevo Il

WashiHston.-A new diseasA. Tie
6oot rot OF the sweet potato. has 70
ceatly been discovered BY the patholo-
xists Of the United States department
,oS agriculture, which threatens to ma
tssially restrict the production OF tho
crop In certain localities. 1t was nrst
observed on sweet potatoes growing
In the vicinity Of the Dismal Swamp.
Virginia, during the summer OF 1919.
AT that time It was believed to be very
limited In It's distribution. since search
for II elsewhere was unsuccessful. The
next summer, however, 1t was found
in other parts Of Virginia. namely, ut
Cape Charles and Keller. 1t is prob
able that 1t occurs elsewhere. At all
OF these places considerable damage
was done to the crop, and tn some
fields N much ~ so to 95 per cent
OF the plants were diseased.
The disease h known a. foot rot
and attacks primarily the lower part
OF the stem from the soil line to four
or I'VE inches above it. The fungus
kills the plants by the destruction Of
the epidermis or bark OF the stem.
Sometimes the organism may attack
the vine several feet from the hill,
usually where the leaf Is attached. and
from there spreads in both directions
Small black bodies about the size OF
. pin point and just visible to the
naked eye are formed on the diseased
spots. These are the fruiting bodies
OF tho fungus. From the destruction
occasioned by this disease during the
seasons OF 1912 and 1913, It Is not I'M
likely that It may be serious men.
ace to the crop in localities where 1t
occurs. To what extent 1t may spread
cannot be foreseen, though it is likely
to be confined to somewhat humid
regions.
The disease may be distributed in
several ways. It has been found In
the hotbeds on the slips and is prob
ably. carried on them to the field. 1t
has been shown also that the growing
organism will grow from the affected
potato onto the slips growing there
from. Furthermore, the fungus will
grow from diseased plants onto the
potatoes produced from them. The
organism causing the disease lives
over the winter on the dead vines in
the field and may infect healthy plants
when set out In the spring.
The sale and exchange of potatoes
or slips is another method of distribut-
ing the disease from one farm to an
other, or from one locality to another
This disease, like many others of q
similar kind, may be distributed on
farm implements, on the feet Of cattle
or horses which roam from one field
TO another. The spores may even be
carried with dust during strong winds.
In view OF these facts, 1t Is apparent
that sanitary methods should be en-
pl0yed In controlling the disease.
These should consist in the careful
selection OF only sound, healthy pota-
toes for seed. The soil for the hot
bed should be obtained two or three
feet below the surface after throwing
on the top layer, or from woods where
there is no possibility that it might
be infested. Healthy slips produced
by these methods should be planted on
ground where sweet potatoes have
never been grown, or at least where
the disease has never occurred.
Healthy slips planted on diseased soil
will become diseased. Neither seed
sweet potatoes nor plants should be
purchased from localities where this
,djcoaan 10 .nrovooonf Tho HiCao1a will
likely increase each year If sweet po-
'tatoes are planted continually on the
same ground.