Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1918-09-24


Another business prOposiiiun?"
asked.
'.No," he said, "but IFS the first NOV.
be has made during the last year and q
half without consulting his farm accoun,
book and figuring out whether or not !,
would be the thing to do from financial
standpoint"
Late Blight of Potatoes.
HOW DOES 1T LIVE OVER WINTER AND
HOW DOES IT sPREAD9
Letters addressed TO the Maine Agri-
cultural Experiment Station indicate
that there Is need OF wider publicity
relative to what has been learned in
Maine and elsewhere regarding the above
questions. A recent inquiry indicated
that the writer thought the disease lives
over winter in the SOIL This 10 . natural
| Inference since the organisms tina, cause
certain other diseases of potatoes not
only are carried by the seed tubers but
persist In the soil for varying periods
after they are once introduced. Since at
the present writing late blight can be
found to some extent in all but the most
thoroughly sprayed fields over q consid-
ersbls area Of the potato growing sec
tiOns of the state, . discussion of the
manner In which the disease apreads and
the agencies concerned therein 10 timely.
As is we'll known late blight, often in
correctly called "rust," 10 caused by q
fungus which not only destroys the foli-
age but causes Q destructive rot of the
tuber as we'll. Frequently the greatest
loss comes from tubsr decay. Typically
this is Q dry rot, causing q rusty-brown
discoloration of the outer portions OF the
tubsr. In severe outbreaks, occurring
In the field at harvest time and soon
thereafter, the disease on the tuber pro-
crosses with great rspidity aud the
entrance Of secondary organisms pro.
duces . soft, mushy, sinking decay
which is too familiar TO the experienced
potato grower to require description.
Fungi ss Q rule reproduce themselves
by means of relatively simple bodies
called spores which serve o similar pur.
pose to that of the seeds of higher
plants. The late blight fungus belongs
to class of which several representa-
tives produce reproductive body capa-
BILE of living over winter out of doors.
The results of certain Investigations
have indicated q tendency on the part Of
the late blight fungus to do this but
there is no conclusive evidence that
these bodies ever develop sufficiently to
function In this way.
The only known way that late blight
lives over winter is by means of tubers
affected With dry rot. Repeated observe
tions show that partially decayed seed
pieces from such tubers, when planted,
are stimulated to early germiuation.
The fungus attacks the young sprouts
and later spreads to the parts above
ground. It then throws out branches on
the surface upon which are produced
large numbers of delicate, thin walled
spores. The spores fall on nearby
leaves of healthy plants, germinate and
send fungus thread into the TISSUES.
Here the fungus branches and ramifies
through the leaf, killing the tissues and
eventually producing the charac! eristic
bro wuish blotches on the leaf. The un-
der sides OF the outer portions OF these
diseased areas, more especially In the
morning or on rainy or cloudy days.
show q Delicate frosty covering made up
of hundreds Of fungus branches, each
carrying numerous spores. All OF the
above takes place before the owner OF
the field 10 aware that the disease is
there, II the lower leaves Of the healthy
plants are thoroughly coated with Dor.
dssux mixture early in the season and
spraying 10 followed up to protect new
gro With the disease cannot get beyond
the first stage mentioned above, for the
pro otsctive spray ID on the Leaf In advance
of the spore of the fungus.
The spores of the late blight fungus
are also readily killed BY drying. Hence
hot sunshiny weather checks the spread
of the disease, while moderately, cool,
cloudy or rainy weather fsvors 1t. Tho
spores have no means Of getting from
plant to plant of themselves but they are
light and are very likely readily carried
by the Wind. Once the upper leaves are
diseased 1t 10 evident that those below
may be infeoted a. the result OF spores
falling on them. Rainfall both by wash
| ing and spsttering 10 undoubtedly an
important factor. Moreover II tempera-
lures are right the spores OF the fungus,
instead of terminating directly, may
each prod nee several free, swimming
bodies whioh move about in Alms of rain
| or dew on the leaf. After they come to
rest they also throw ont germ tubes
| which penetrate the leaf tissues and
ktbus start new centers Of disease. Sim
ple contact of diseased and healthy parts
| either caused By being blown By wind or
movemsut produced by any other agency
/ In also q factor. Potato tubers become
infected 40 the result Of the spores be-
ing washed down into the soil from the
ldiseased leaves.
/ Thsre 70 . common notion that insects
are an important factor In the spread OF
this disease and this seems 30 be rea.
,onable suppositioH. Some unpublished
obseryationa made by the pathologlst Of
shis station as the result Of IN outbreak
Of late blight In IN experimental green
house bear on this point. Ciroumstan.
tial evidence strongly tndicatsd that
either the f1es-beetle or the potato sphid
vere the respensibler agents In carrying
| the disease from the field to the green
house, but positive proof was not OBJ
tanned. No positive evidence Was oo'
taiued that the spores Of the fungus
adhered to the bodies of the aphids. On
the other hand itCwas apparent that fhe
flea- beetle might act - . carrier, oct
this was BY no means the universal rule
whore they were taken from plants On
vhich IN abundance of the spores OF the
late blight fungus were being Produced
ICHAs. D. WOODS, Director.
Watsr lnjurss Hggs.
Wsshsd eggs do not retain their keep
ipa qualities. There b . gslatinous sub.
stsncs on eggs, which seals The pores o.
The shslh and water seams 70 dl.solvs IL
When thls substsnos ID dissolved the sil
| n admitted and decomposition begins
| WsShine also has teudesey to harder
the shell, letting too much moisture
escape, and thus ipjuring the vitality o.
Dirsy ssgs should not b sent e
market, however. They may DO saieiy
treated b, using ~ Swoolsn rag Dol!
sliehtly dsmpsued With water to rub on
| the dirt. Stains on eggs may % re
moved With oiBse vinegar. O'san ness
viii Insure clean sgga.
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