Alma record. (Alma, Mich.) 1878-1928, 1909-05-20
TREATMENT OF POTATO SCAB.
Michigan Agricultural College issues Bulletin
Of Interest TO Potato Growers.

Bulletin No. 81, regarding the treat
ment of seed potatoes to prevent scab
has just been issued by the Michigan
Agricultural College The author of
the bulletin. Prof II j. Enstance,
says:
Potato scab is fungus growth
on the skin of the potato. From this
fungus grow spore which live over
winter in The soil and on the tubers
in storage. Therefore, planting scab-
by seed generally but not always
results in scsbbv crop. The soil
which has produced scabby potatoes
is almost sure TO produce a scaSby
crop if planted with potatoes again
the following season.
When potatoes are to be planted on
land free from scab the seed tubers
should be disinfected to prevent the
introduction of the disease by means
of scab spores on the seed but If the
LAND is already thoroughly infected
this is of little-use. Distinction may
be accomplished in different ways-bv
soaking the seed in corrosive sub
Innate solution or in formalin or by
exposing ii to formaldehyde gas.
: Make a solution containing one
ounce of corrosive sublimate in seven
gallons of water. Soak the tubers in
this for ~ hours. This treatme Mt
has been largely superseded by the
formalin treatment. which is equally
effective, more convenient and safer
Corrosive sublimate is very poisonous
In 30 gals. water pour one pint of
formalip 40 per cent formaldehyde
Soak the uncut tubers in this solution
for two hours. The same solution
NAV be used several times. Take
care that the treated tubcrs are not re-
infected by coming in contact with
bags or crates which have held scabby
potatoes. 1t is better TO make this
treatment only few davs before
planting. Formain is not poisonous.
Treated seed not needed for planting
NAV be used for food or fed to stock
with safety.
Scabby potatoes are more common
on clay and loan than on sandy soil.
These soils are more apt to be acid
and on acid soil scab is not common.
The scab fungus does not thrive IN
this kind of soil. Soils which are
neutral or slightly alkaline are most
favorable to scab. Unfortunately, the
soil conditions most favorable to large
yields are also most favorable to the
growth of the scab fungus. Puttirg
lime. wood ashes or stable manure
upon the potato field tends very much
to increase the trouble with scab.
These substances lessen the activity
of the soil and thereby make it more
favorable for the growth of the fungus
which may be in the soil They do
not cause the scab rs some believe,
simply make favorable conditions for
its growth.
BY blowing under some green crop
iihc ClONci vi rye "A SOll tndt 0hb De-
come alaline may he brought hack TO
an acid condition. This is some help
but cannot be relied upon entirely to
prevent scab. An application of sui
plate of ammonia will reduce the loss
from scab as we'll as supply plant food
A rotation of crops will assist. con-
siderablv. in the control of scab. On
soil badly infested with scab it is
usually cheaper to abandon potato
culture for a time than to try and
com bat the disease. Scab may persist
in the soil several years just how long
is unknown. Much depends on the
treatment of the soil and kinds of
crops grown. Probably, the time is
shorter in titled land than in sod.
Beets harbor scab so do turnips,
probably.