Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1890-11-07
THE POTATO DISEASE.


dicnIe Remedy.
The following is taken from pamphlet
OF the Danish Professor j. l.. Jensen, di-
rector of the bureau Ceres" in Copenha
gen
The potato disease first appears in the TO
lage of the plant, and then spreads to the
tubers The disease consists of fungus the
spores Of which propagate at an extraor-
dnarily rapid rate, and are blown by the
wind from field to field, as well as from
plant to plant By a great number of ex-
periments, carried out very carefully all
over Denmark, it was found that the dis
ease spread from the foliage down to the
tubers in about seven days after the foil
age was attacked. The way it spread was
10y the spores falling from the leaves and
stem of the plant on to the soil and being
then washed down to the tubers by the
rains. On taking up the potatoes in lay
ers, the top layer, consisting of those near
est the surface and nearest the stem, was
diseased to the extent of about 50 per cent,
the middle layer to the extent of 30 per
cent while the low est layer was only dis
eased to the extent of 3 per cent.
Those potatoes nearest the stem of the
plant were also always found worse dis.
cas,d than those farther away. This also
went TO prove that the spores came from
the surface, and in this case came down
the opening in the soil made by the stem.
This gave the idea that the spores could not
reach the tubers if the soil was dense
enough, and a great number of expert
ments were tried all over the country to
prove or dsprove this idea The result
was startling, and may be roundly put as
follows Where no moulding or earthing
up was done the percentage of diseased
potatoes was "a, where the moulding was
imperfect -, and where the moulding was
perfect one only
Some 100 farmers were engaged in these
experiments, and the results were all care
fully tabulated, and the experimental fields
visited and carefully inspected. The knowl-
edge thus obtained proves that to entirely
prevent the spores of disease reaching the
potatoes it is necessary lst, To plant the
seeds about II inches apart, and have the
rows about 30 inches apart I'd. To mould
up into broad ridge, three or four inches
high and 10 to - inches wide, after the
first wedding. 3D.. To mould up again
when the disease first appears in the leaves
of the plant, or within seven DAYS of its
appearance The second moulding up to
be as high as possible, and 50 arranged as
to bend over the tops of the plant, so that
the spores when mature may fall into the
space between the rows, and not on the
ridges. This can be done by earthing uI
ON one side only. There should not be less
than 81 inches of soil on the top of the
uppermost layer of tubers 1t was found
that one moulding up would not do. II
the ridges were moulded up high enough t.
repel the disease at the beginning, the crop
of potatoes was less, in consequence Of the
young plant being too much covered up
The first moulding or earthing up should
he when the usual wedding takes place
and should be flat and broad. The second
moulding should not be done till the diseas,
shows itself in the plant.
A small special experiment was made il
one field where the disease was very prev
alent. In the second thigh moulding up
the soil was beaten close with the spade a
the operator went along, and this so effect
uallv kept out the disease that the percent
age fell from "a to D. Hardly a bad pota
to could be found, though two-thirds wer
bad in the ridges not moulded up. 1t wa
found that the presence of worms, grubs
etc, in the soil increased che disease in pro
portion to their numbers, that is, their Dor
ing operations let in the disease spore
through the soil
Though the method of double earthinI
up was found to almost entirely protect tn
potatoes from the disease, it was feare
that, when taken up, they would still com
in contact with the spores while bein
taken up, and thus become infected afte
all A great many experiments were mad
on this point, and the results may be put a
follows If taken up before the tops ha,
completely withered, they did become in
fected and to a very large extent. If tn
tops were cut off and taken away befOr
the tubers were lifted, disease still shove
itself in few days, though they were per
tectly sound when taken up This was ex
pected, as the spores which had alread
fallen from the tops were on and in tn
soil, If the tops we're allowed to complete
w wither before the tubers were lifted, tn
spores died from want of food, and no dis
ease whatever showed itself, either at lift
ing or afterward If the tops were Gu
and taken away as soon as the tubers wer
ripe and before the spores had fallen i
any great quantity on the soil, the diseas
which made its appearance in the potAtot
was not very great If the tops were Gu
and taken away, and the tubers not LITE
for another week or so, very little dseas
resulted as the spores were mostly deaC
If the tops were allowed to wither, an
then month allowed TO lapse before tn
tuhers were taken up, no disease at all e'
er manifested itself and it is believed tn,
fortnight's time would have been equal
effective.