Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1914-05-05
New Diseases of the Potato.

that many of the fundamental factors
concerned in the distribution and spread
of diseases of plants are essentially the
same as is the case with diseases OF man
and other animals. There is considerable
basis of truth in such observations as
1--WE never used to hear Of such things
as these" or "They did not have dis
eases like these when | was boy" but
it is not necessarily true that these So
called new diseases are mere creations
of the imagiuations of animal and plant
pathologists. No intelligent person, no
matter how skeptical he may be, can de-
nv the fact that during the past fifty
wears many important and far reaching
discoveries have been made which have
greatly added to our store of accumulat-
ed knowledge. Electricity is not new,
but man now recognizes and makes use
of manifestations of this force not
dseamed of by our grandfathers. Equal
ly as important discoveries have been
made relative to diseases of animals and
plants as have been made 10 the realm Of
electricity or similar lines of research.
Many so-called "pew diseases" were
simply not recognized in the past.
The rapid increase in trade, commerce
and travel during the last hundred years
is another very important factor con-
cerned in the appearance OF new diseases
of plants as well as animals. A malady
which is new for one locality may have
existed for years in some other remote
part of the world
Where considerable areas Of land are
given over to the cultivation of single
crop largely to the exclusion of all 9TH
ers, particularly il there is much traffic
back and forth in the line OF seed for
planting, problems of plant disease con-
| troll and spread are much more serious
than In those sections where there Is less
specialization in crop production. Spe-
cialized agricultural industries present
plant disease problems comparable in
nature to those experienced in large
cities and ports of entry like New York
relative to diseases of man. However,
in connection with our own potato grow
ing area certain important differences
should be noted. New York has for
years allowed no foreign emigrant to
land until he has been thoroughly in
spected aud declared free from danger
GUS diseases. With us, up to very re-
Gently, all the potato importer had to do
| was to pay the custom duty, and he
could import and plant without any in
spection whatsoever, as many bushels OF
potatoes as he liked from the worst dis
ease infected regions of Europe or other
parts Of the world.
Blackleg, which has spread to nearly
all the great potato growing districts OF
America, came to US 10 this way. 1t had
been common In England and certain
other parts Of Europe for some time.
Canada was reported to be pretty thor
oughly infested with 1t before it was re-
corded in the United States, and there is
plenty of evidence that it was brought
from there to Name.
Blackleg was aud is in many respects
a serious disease, but We have discover
ed very easy and efficient means OF its
eradication and control. Now we are
confronted by another undesirable Euro
pean emigrant, powdery scab. In Maine
this has come to US largely from Canada,
although there is reason to believe that
later investigations will show that II has
been carried to other parts OF the ooun-
try by means of potatoes imported d.
rectly from infected districts Of Europe.
Powdery scab has existed in Europe
for many years, and one English pathol-
ogist, some twelve years ago, stated that
il was well known to be of long standing
in Great Britain and Ireland and to be
widely distributed. The first report in
America came from Canada the latter
part of 1912. The first in the United
States, May, 1918, was from tuoers re-
ceived at this Station from Nebraska and
Massachusetts. Almost simultaneously
with this DR.. Melhus Of the Bureau OF
Plant Industry reported case from
Maine. Since then il has been found to
be very common in nearby portions OF
Canada and rather widely distributed in
one section of our own state bordering
upon the infested region.
| Powdery scab may be confused with
common scab. The individual spots
produced by the latter when mature are
| larger and as a rule are nothing more
than superficial ulcer which does not
iniure the keeping qualities OF the tuber
| Powdery scab first appears as minute
pustules or wart-like bodies occurring in
patches CT scattered over the surface oil
the tuber. The pustules enlarge, be-
come raised, and when they break
through the skin present ragged mar
gin where the latter has been ruptured.
| If the top of the pustule is removed the
interior is filled with dark colored
powder having slight olive tinge. II
affected tubsrs have been handled con-
siderably and the surface Of the pustules
rubbed off so that the dark colOred pow
der is removed 1t may be difficult for the
/ ordinary observer to distinguish between
| it and the small spots OF the common
type of scab. However, the arrange
ment, shape and size of the LESSONS often
give a clue as to the nature OF the dis
ease. II any of the powder remains 1t is
very easy to identify powdery scao oy
means of microscope. The average OBJ
server soon learns to distinguish the two
diseases without this aid.
| Potatoes affected with powdery scab
show a strong tendency to dry rapidly
and wither up making them unfit for
use. Sometimes decay will start where
these spots are numerous. Where the
disease is very severe another form may
appear. We have not seen this in Maine
except on tubers grown in the green
bouse. One English writer stated that
this form Is more apt to occur In wet
SOIL In this stage the tubers instead OF
showing the pustules as described show
rather soft tuberous outgrowths ire
quently at the seed end, these later dis
appearing leaving distinct, eroded,
cankerous area in the potato.
Powdery scab is caused by one OF the
slime molds which latter are classed
lamong the lowest living things on the
border between the animal and vegetable
kingdom.
| Both infected soil and seed may cause
the disease. One experiment 10 recorded
in Ireland where the spOre balls OF pow
dery scab were able to pass through the
digestive tract of pig uuharmed, max
Ing its manure q source of contamins
ton. Potato culls should not DO FED 10
stock without cooking.
There is some uncertainty as to nov
efficient germicides are iu controlling
, powdery scab. One Investigator IN ire
liand reports . material reduction oy
aoaking the seed in formaldehyde AND
by wetting the surface of tbs tuoers ane
rolling them in flowers Of sulphur a
clean crop was obtained BY soaking seee
three hours in one percent solution o.
: copper sulphate, but the yield was ma
terially reduced. No satisfactory re
ants were obtained from soil treatment
Various forms of lime applied to th'
II .-..oa.oA ha amnnnt n