The Redwood gazette. [volume] (Redwood Falls, Minn.) 1873-1940, 1890-07-31
AGRICULTURAL HINTS,
THE POTATO BLIGHT.

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Prof: Clarence NJ. Weed. OF the Ohio AZ.
rlcultural Experiment. st .tion, Gives
Some Inform alto, ABOUT 1t.
The disease commonly known as 10
tato blight potato rot or potato cholera
Is caused by one or more species OF the
minute parasitic plants known as fungi.
As rule American writers have as,
sumed that the'species concerned. is the,
same that has been present in Europe
for many years Phytoph thora in
festans. While there is no doubt that
this Is often the cause, there is also
good reason for believing that other
species of fungi are sonnet mes respon-
sible for the blighting of the leaves
and consequent injury to the. crop.
When attacked by Phytophthora in
festans~ the potato tops, blight, the
tubers rot and the leaves are covered
with fine, whitish mildew. But in
many of the Western States. the blight
often appears without the mildew On
the leaves or the rotting of the tubers.
Whatever precise species may be
found to cause the dis 'ased condition,
it is we'll settled that 1t is of fungus
origin, and that the fungi are chiefly
propagated by spores-infini tesimal
bodies corresponding in function to the
seeds of higher plants. When these
spores fall upon the. leaves of the potato
they terminate and enter the leaf It's
sues where the mvcelium-a growth
analogous to the roots of the higher
plants-develops at the expense of the
leaf to such an extent that the latter is
destroyed. Experiments made lastyear
in New Jersey by Colonel A. w. Pearson,
and in Ohio by the writer, indicate that
this disease may he prevented by the
use of Bordeaux mixture. Colonel Pear
son planted several plats of late pota>
toes and sprayed all but one of them.
The treated plats were little or not at
all affected, while the untreated one
was destroyed. In the Ohio experiments
fifteen feet of the ends of large num-
Der of rows were treated, and at the
time of harvesting it was found that the
treated vines had suffered very much
less injury Than those not treated, the
Increased yield of the former being at
the rate of sixty -four bushels to the acre.
The standard formula for the BOr-
aeaux mixture is as follows:
''Dissolve six pounds sulphate of cop
per in sixteen gallons of water; in an
other vessel slake four pounds fresh
lime in six gallons OF water. When the
lime mixture has cooled to the temper
ature Of the air, pour it slowly into the
copper solution, mixing the fluids thor
oughly by constant stirring"
In our Ohio exnerimontS we diluted
this solution about one-half. using six
pounds copper sulphate and four pounds
lime to fifty gallons water instead Of
twenty-five gallons. as ordinarily recon-
mended We usually made it by filing
our Nixon barrel machine, which holds
dfty gallons, nearly full Of water, and
then adding three or four gallons hot
water in which the six pounds of copper
sulphate crystals had been dissolved.
+ The freshly slaked lime was then poured
in, and after a thorough stirring, tho
mixture was ready for use. Sometimes
Instead of the crystals we used powdered
copper sulphate. in which case it was
i not necessary to heat water to dissolve
1t, the powder being simply put in the
barrel of clear water and was soon dis
solved. When we wished to add Lon
don purple, we simply put it in either
before or after the mixture was made.
| am not sure whether this dilution oil
the formula is advisable or not, as Prof.
Scribuer has found in his grape-rot ex-
periments that the best results were OBJ
/ tained from the standard formula riven
sbo g American Agriculturist.