The Abbeville press and banner. [volume] (Abbeville, S.C.) 1869-1924, 1910-04-13
CLEMSON EXTENSION WORK.
Black Rot Of Sweet Potato.

One Of the most wide spread and most
destructive diseases in this state at pres
ent is the black rot of sweet potato
This disease occurs quite commonly and
does considerable damage on potatoes
both in the field and in storage. The rot
is caused by a parasitic fungus which
under certain conditions, is able to pass
from one plant to another and thus spread
the disease.
The trouble first appears as brown OF
black patches or notified, discolored areas
quently these discolored areas are OBJ
served in potatoes when they are dug, but
at this stage the only seems to penetrate
the skin and is apparently doing no Sc
rious harm. Later the rot extends Into
the potato'and causes the affected area to
turn black and to emit the Odor which Is
so characteristic Of rotton potatoes. When
such potatoes are stored in warm, moist
places, the rot producing fungus becomes
especially active and by means Of tiny
spores, which are produced in small
areas, spreads rapidly from one potato to
another. Under such conditions the dis
ease is also spread by the filaments OF the
fungus growing from the rotten potato
directly into adjoining healthy. potatoes.
In this way the rot might spread to every
potato in a bank.
II slightly diseased potatoes are stored
in a place where conditions are unfavor-
able for the development Of the rot, they
frequently remain partly rotted until
spring. The real danger Of spreading the
bedding such potatoes. Slightly diseased
potatoes seem to sprout as readily as
healthy ones. and the slips from such po-
tatoes are diseased. The disease trans.
ferred with such slips to the field remains
on the plant and attacks the potatoes when
they develop. The fungus which causes
black rot also lives over In the soil from
! year to year and where potatoes are plant
ed every year on the same land, the dis
ease constantly gets worse.
To prevent black rot then we must:
First, secure disease free seed for plant
ing. Second, avoid planting potatoes on
the same land for two yearsin succession.
Qnite frequently it is impossible to Sc
cure potatoes for bedding which are en-
tirely free from disease. In such case 1t
is we'll to use vines instead Of slips, for the
fungus which causes the disease remains
in the vicinity of the the plants. 1t does
not live in the vines and leaves, 70 vines
grown from diseased potatoes. il planted
on land which Is free from disease, will
produce sound potatoes.
ENONJ 90 L NdNC Solu, DluCh lOU OSSuio va
the majority OF the farms in this state,
and is responsible either directly or in
directly for the loss Of thousands OF dol
lars worth Of potatoes annually, 80 it is
well for every farmer to look out for 1t
and guard against it's spread. If you have
already bedded your potatoes and are not
sure that they are free from disease,
plant as much Of your crop as you can
from vines and on land not previously
planted in potatoes. When you gather
these potatoes, bank separately the ones
grown from the vines and the ones grown
from the slips and note the keeping
qualities Of each.
|! Potatoes should not be banked for two
years in succession In the same place, be-
cause IN fungi which cause these rots
will live over in the old banks and attack
the new potatoes as as soon
as they are banked. Where potato houses
or cellars are used for storing, they
should be cleaned out and disinfected be-
fore the new crop Is put in. This can be
done by cleaning them out thoroughly and
then spraying the walls and floor with a
8 per cent solution Of formaline or a l per
cent solution Of copper sulphate (Blue
Stone).
Fl. w. Barre,
Botanist S. c. Experiment Station.