Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1879-08-20
LETTERS on NATURAL HISTORY.
THE POTATO DISEASE.

Mold is a word in common use, and all
will tell vou what mold is, yet each will
perhaps tell you of a different kind. This
very numerous family are called Hyp-
honycetes, that is. fungi that grow by
throwing out delicate threads.
OF course there are several distinct
groups.
To the common eye, unaided by the mi
croscope or observation, mildews, moldi-
ness, and similar microscopic plants
would be readily confounded. But the
mildew is much more highly developed
fungus, and though apparently as danger
Gus, is not so to the same extent. The
egg mold (Oidium) which covers and
suifocates the young gooseberry. or the
grape, readily yields to agents which will
destroy it, and set free from its threads
the swelling fruit; but the potato mold,
for instance, is the inception of the potato
rot, which is so dreaded. The "molds," q"
then, as Russell says, "are fearful para
site plants, which riot on the tender It's
sues of other plants, and eventually cause
their death. There is in this country as
many as ten known fungi infesting the
potato. 1t is on this account that those
attempting to describe the potato disease
have differed so widely from each other,
while all have brought up some facts
The true potato mold, causing SO much
mischief, is now generally admitted to be
the PorOnOSpOrd infcStanS, and were it not
for its effects it would be regarded as a
thing of beauty. Were the flies or insects,
which are are so literally endowed with
eyes, and quite unconcerned about crops,
to investigates; the leaves of the potato
would be quite pretty set of objects t.
examine, presenting white, many branch
ed, and beaded twigged plants, with egg
shaped seed bodies on the tips Of the
branches. These vegetable growths issue
from the stomata( breathing spores)of the
leaves, choke up the internal and external
passages, and prevent a healthy action
from being maintained. Soon the leaves
become paler, or yellow, then discolored
spots appear, and the stems are covered
with dark patches; even the stocks are
filled with clotted substances, and sooner
or later putrefy, and lastly the tuber suf
fers, and the rot rapidly increases.
1t was toward the close of the summer
of 1915 that the world awakened to what
they supposed new disease in the potato
crop; and one which threatened its entire
destruction. Erly in September its rava
people. 1t extended to Scotland, Englant
and the continent, and rewards were offer
ed for detection Of the cause and host Of
observations were made with no valuable
results.
1t is only by long years of patient study
that natures works are found out, and i
will be longer still before any sure pre-
ventative will be reached. There are
however, some things that tempt this fun
gus growth that is so destructive; Us close
planting, damp land, weeds that shade tht
crop, etc.
AS there are some differences of opinion
in relation to the actual condition of the
potato, favorable or otherwise, to the rot
l copy from the observations of others.
&" Some eminent chemists, such as DR.
Lyon Playfair. believe that the potato
plant, when healthy. is not subject to at
tacks from fungi. In lecture delivered
by the doctor before the royal agriculture
society of England, Dec. 9, 1915, he re
marked that much had been said anC
written with regard to the source of th'
disease, and since minute fungi had beel
assigned as its cause, potatoes, apples ant
other fruits had been inoculated with fun
gus spores, and had become diseased; bu
if there was not some previous disease il
the potato itself, how was it that some va
ricties of potatoes escaped while CROWN
in the immediate vicinity, while other
were attacked?'" The disease, he believ
ed, arose flom structural or chemica
causes.
When decayed potato was examine
it WAS found that the diseased spots wer
always in the region of the spiral vessels
whose function it is to carry air into tn
tissue of the plants. He believed the di
ease originated in the oxidation of tn
tissue. The Rev. M. j. Berkeley, tt
leading myoologist of England, on Ii
other hand, contends that fungus Botryt
infcSlanS, or, as now classed under til
new genus, PeronoSpora infeStans, wi
attack the healthy tubers; but the questio
arises at this point, what means have "
of ascertaining the perfectly health
structure. and chemical state of tubers
Every farmer plants what he deems sour
tubers, yet in the majority of cases, sin,
1945, the crop during very moist seasol
has been more generally affected than
was prior to that date.
The severity of attacks of fungi {
plants will depend in some cases on Il
density Of their organic structure and Il
solubilty of their nitrogenous matter. tt
nitrogenous principle of potatoes, for e
ample, is soluble in water, that of turni
nearly insoluble. The former, therefor
ferments more readily than the latter. II
leaves of healthy peach tree. VIII
placed in moist atmosphere at about Z
F., resist fermentation for months. viii
those Of peach tree affected with Il
yellows," placed under the same gener
conditions, will quickly ferment and
come covered with the fruit of the flung
mucor. The first possess an antiseptic
property, the second are deficient in it.
two blocks of wool, one of lockwood al
the other of soft pine, are placed in a fu
gold solution, the first will resist Il
action Of the mycelium for long tin