Year: 1876

! ~ Is NIcIc I'LL 1tflAIso CiAAiASo iiioe SAeSi'' .
wide new territory, it grows more
vigorously and increases more rapidly
than ever again. All the great scour-
ges that have cut short the food sup
ply of the world such as weevil, smut,
rust, blight, are caused by some min
ute form of life. Within twenty-four
hours from the time field Of potatoes
has been green and growing, without
a sign of blight, the same field has
been seen with nothing but a mass of
rotten vines and rapidly rotting tubers.
Many were the conjectures at that
time as to the cause. The common
opinion was, that L" The cause is the
heat of the sun and the moisture of
the soil and air, and the effect of cer-
tain manures." Many also felt sure
that it was because the tuber, being
long reproduced without starting again
from the seed, had deteriorated till it
could do nothing but rot, all of which
conjectures were about as much to the
point as that answer to the famous
conundrum-' &c What is the cause of
the potato rot % Answer, It is caused
by the rotary motion of the earth
so the common-taters say To-
day, we know that nothing "rots"
of itself; that the reason that air and
moisture " cause decay" is that the
air sows fungus germs and heat of
the sun and moisture" are favorable
conditions for their growth. At any
rate, the cause of the potato rot is q
fungus that has been carefully and
accurately studied, and when we are
told that observations have "proved"
heat moisture and certain manures
originated" the rot or caused" it,
we know that the observer has simply
made the old mistake of saying
"cause" instead of &c condition."


Perouospora infestans is a fungus
which is found on all varieties of
the potato, occurring even upon the
wild varieties in South America. The
conditions of it's growth are like those
of all funguses moisture and warmth.


It affects both leaves, stems and tu-
bers, sending it's mycelium throughout
the entire individual it infests and
coming to the surface with it's little
mushroom forests of reproductive seed
vessels, after the manner I have de-
scribed. The spore of the perouospora
infestaas furnished with celia, by which
it can swim away at q very lively rate
whenever there is a heavy dew. The
mycelium of this fungus destroys the
vegetable fiber, through which it runs,
and once it has possession, the other
forms of funguses come in and there
is nothing left of vine or tuber that has
any roundness or life. When the rot
first makes it's appearance, generally
the last of July or the first of August,
you will see the leaves in certain spots
over the patch beginning to turn black.
Examine the under side of the green
leaves and you find something there
like a very delicate frost. That is your
mushroom forest of spore cases that
are burdening every wind with billions
of spores. Your patch is doomed, and
there is no escape. And yet let us
think about it and consider whether
something may not be done. If the
tubers are already formed in the
ground much may be done toward
saving them.
When the blight first becomes visible
not tuber in the field-new-is pro-
badly affected. But there are two
ways in which the tuber may become
affected, 1st, the mycelium already in
the vines and rapidly growing may
and will soon extend down the stems
to the tuber. End, The spores set free
above may be washed down through
the soil and there find the proper con-
ditions for it's growth. Now a simple
preventive measure will occur to any
one to prevent the first method of in
fection-that is to pull the vines. I
may tell you here that I tried this
method this year with marked success.
I pulled the vines within a week from
the time my patch was struck"
Only left about 50 hills in one corner
where they seemed to be yet growing
nicely and as I fondly hoped not much
touched. In digging those potatoes
last week. I did not find three tubers
affected in the whole patch till I came
to the hills upon which had left the
vines. In the first hill of these I found
six potatoes perfectly rotten and al
most all affected Other hills were not
SO bad, but they were nearly all more
or less affected. Now this in itself is
almost conclusive in favor of pulling
the vines as soon as the patch is
! touched. Moreover, as sustaining the
argument that the mycelium of the
fungus will continue down the stem
and affect the tuber I have this evi-
dence to offer. The rotten potatoes
we're mostly on the top of the hill.
Many in a half-decayed condition
showed that the rot had begun at the
point where the vine and tuber were