The National tribune., 1899-05-18
POTATO DISEASE.
Timely Suggestions as to Treat
ment Made by the Depart.
ment of Agriculture.
BY D. T. GALLOWAY.

4 number of diseases affect the Irish
potato in this country, and the losses
they occasion are often serious drain
on the farmers income. The object of
this bulletin is To briefly describe the
most important diseases and TO outline
methods of treatment which experience
has shown TO be successful in holding
them in check.
POTATO LEAF FLIGHT, OR EARLY BLIGHT.
This disease is widespread and destruc-
tive. 1t is confined to the leaves and
green stems, and appears about the time
the tubcrs begin to form, but may be
noticed earlier if the growth of the plants
has been checked in any way. The FIRST
indication of its presence is the appear
ance on the leaves of grayish brown
spots. which soon become hard and brit
tie. The disease progresses rather slowly,
the spots gradually becoming larger, es-
pecially along the edges OF the leaflets.
At the end of 10 days To two weeks hall OF
the leaf surface may be brown, withercd,
and brittle, while the rest is OF a yellow
ish green color. Three weeks or Il month
may elapse before all the leaves sue
cumb The stems in the meantime re-
main green, but they. too, finally perish
through lack Of nouriShment. The tubers
stop growing almost as soon as the leaves
are attacked, and as a result the crop is
practically worthless.
Early blight may be held in check by
the application OF the fungicide bordeaux
mixture. This is prepared and applied
as follows: Pour into a 80 gallon barrel "a
gallons of clean water; then weigh out
six pounds of crushed bluestone, or cop
per sulphate, and after tying it in a piece
of coarse sacking suspend the package
lust beneath the surface OF the water by
means of string tied to Stuck lald
across the top OF the barrel. In another
suitable vessel, such as tub or malt
barrel, slack four pounds OF fresh lime.
Slack the lime carefully by pouring on
small quantities of water at Il time, the
object being to obtain smooth, creamy
liurid, free from grit. When the lime IS
Stacked add sufficient water to make %
gallons. As soon as the bluestone is dis
solved, which will require an hour or
more. pour the lime milk and bluestone
solutions together, using a separate bar
rel for the purpose, and stirring con
stantly to effect Il thorough mixing. IL
sometimes happens that sufficient lime IS
not added, and Il result the foliage
may be injured. To be certain that the
mixture is safe hold a steel knife blade
in it for two or three minutes, and if the pol
ished surface of the blade shows copper
coIored tinge add mo.e lime, but If it stays
bright the mixture is safe to use. Appll-
cation OF the mixture should begin when
the plants are four to six inches high,
and should be repeated at inervals OF II
to II days until five or SIX treatments
have been made. BY adding eight ounces
of Paris green to each barrel OF the Bor-
deaIx mixture a combined fungicide and
insecticide is obtained, and this Will pre-
vent the attacks of the Colorado potatu
beetle. the flea beetle, and other insects:
Before adding the Paris green it should
be mixed with Il small quantity OF water,
and when n thin paste IS obtained this
should be thoroughly stirred into the bar
rel of U5or;leauX solution.
The success attending the application
of the Bordeaux mixture depends IN large
measure upon the thoroughneSS with
which it is applied. To reach all parts
of the plants above ground with hne
spray requires good force pump and
suitable nozzle.
POTATO BLIGHT, LATE BLIGHT, OR ROT.
This disease attacks the leaves. stems,
and tubers. Generally the first noticea-
ble effect upon the leaves is the sudden
apuearance of browni5h or blackish areas,
which soon become soft and foul smell
ing So sudden is the appearance OF the
disease in some cases, that fields which
one dav look green and healthy may
within the next day or two become black,
ened as though swept by fire. The RAPID
SDread OF the disease, which IS caused by
a parasitic fungus, is dependent in large
measure upon certain conditions OF moist,
ure and heat. \ daily mean or normal
Temperature bI lFOii - itSICCo W 81 W
rrees Fahrenheidt for any considerable
time, accompanied by moist weather. fur
Dishes the best conditions for the spread
of the parasite. TUbers affected with
the disease show depressed, dark-colored
areas on the surface, while within are
blotcheS and strcalIS Of brOwnish oi
blackish color. Other diseases may pro
ducc similar effects, so that in this case
the changes are not so characteristic as
those shown by the leaves. For many
years it was believed that most OF the
injury to the potato was due to THIS dis
ease, but recent Investigations have
shown that view 10 be erroneous.
The same treatment as recommended
for early blight should be followed here,
and will be found to prevent the blight
ing OF the tops and rotting of the tubers.
In regions where late blight is known to
occur, care should be taken to begin the
application Of the Bordeaux mixture be
fore the attacks OF the fungus. In all
this work il must be constantly kept in
mind that the main object is prevention
rather than cure. Benefit will undOubt-
cdly result if only clean, healthy pota-
toes are used as seed. Decayed and dis
colored tubers should be fed to the hogs,
as it is poor policy to plant them.
BROWN ROT.
This disease occurs in many parts OF
the South, and, in addition to attacking
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