The Wellington enterprise. [volume] (Wellington, Ohio) 1867-188?, 1883-10-31
The Potato Rot.

The rotting of the potatoes Is caused
by a microscopic fungus, PeronosporG
infeStd,aS, which infests the potato plant
BY fungus is understood a plant of q
very low order, the more familiar MEM
bers of which are the toadstools, mush-
rooms, mildews, and moulds. Some of
the fungi live only on decaying organic
matter, and are comparatively harm
less; in fact, are often helpful in hasten
ing decay and preparing substances for
future usefulness. Other species of
fungi are parasitic, growing upon living
things. The bread mould is familiar
illustration of a small fungus which
feeds upon dead matter, while the po-
tato rot fungus is an equally striking
example of one thriving upon living
plant. The mildew of the grape, which
has caused great damage in many vine-
yards, is q close relative of the potato
rot. They both belong to the same
genus (PeronosporG), genus which
contains large number OF species, and
all are destructive to the host plants.
The potato rot fungus consists of
long filaments or threads, which grow
through the substance of the potato
plant, and rob it of juices and induce
a rapid decay. The fungus usually
thahCo It's aPBOdAanCC uDOh bnO
under side of the leaves as frost-like
patches, soon causing the foliage to
curl and turn brown. This frost-like
appearance is due to multitude of
spores which have formed upon the
ends of fungus threads protruding from
the breathing pores of the leaf. There
are many thousand stomata or breath
ing pores to the square inch, and q
dozen or more threads may come out at
each opening. Each of these threads
forms branches, and each branch bears
a spore. This helps to give an idea Of
the vast number Of spores formed upon
a single affected leaf. These spores
germinate quickly and In peculiar
manner-each spore giving rise to sew
eral smaller spores provided with hair
like appendages (cilia) by means of
which they move quickly around. This
is n most admirable provision for the
rapid and perfect spreading of the dis
ease when 1t has once "struck" po-
tato field.
After the foliage has become affected
the disease passes into the stems and
down to the tubers, when the most de-
structive work is done. The farmer
should be on the watch for this fatal
pest of his potato field. Like most
fungi this Peronospora thrives best in
warm, rainy or ''muggy" weather. In
one of the recent press reports It was
stated that the decay was caused by the
wet weather which has prevailed in
many parts of the country. The
weather was only a favoring condition
for the rot plant, as much so as the
rains are aids to the profitable develop
ment of the various field crops.
1t has been shown that disease is first
seen upon the leaves. When the foliage
begins to curl and turn brown, the po-
tatoes should be dug at once, and in this
way prevent the fungus from reaching
the tubers. The potatoes should then
be placed in a cool dry place-the con-
ditions least favorable for the further
growth of the fungus should it be pres
ent. All affected tubers should be
thrown out and gathered with the vines
and burned. This destroys multitudes
of spores which might otherwise live
through the winter and be ready to
propagate the rot the following season.
There has been q great deal said
about ''rot-proof" varieties of potatoes,
but they do not exist Some sorts are
more susceptible than others, probably
from constitutional weakness. Many
prizes have been offered in England for
ihe finding of the best sorts to withstand
the attacks of the rot fungus, but with
out any satisfactory results. Knowing
that this disease Is caused by q parasitic
fungus, the rapid developement of
which Is favored by moist, warm
weather, there Is little hope of finding a
variety of potatoes so abnormal as to
be ''rot-proof. .'-Scientifc american.