Vernon County censor. [volume] (Viroqua, Wis.) 1865-1955, 1906-05-16

First, what Is early blight? The term
blight is often very broadly used
: among the potato growers. even to the
extent of calling an early whitening of
the vines blight. Early blight proper
is caused by a semi-par9sitic fungus
macrosporium solani, It seldom at
tacks the healthy vine directly, hut
, gains entrance after the vine has be.
come weakened by injury. Hence its
prevalence during seasons OF seri-
ols damageg from the beetle. The APP
: pe..rance of yellow leaves and dark
circular spots upon the foliage in
dicates the early presence of the dis
ease.
Under favorable conditions this
appearance may develop to the extent
of giving the entire field a speckleI
and blackened appea ance. The stalks
turn yellow, grow spindly, and ripen
prematurely several days in advance
of the season. During unfavorable
seasons for fungus development, tle
disease may exist unobserved during
the period of most active growth. and
later multiply rapidly at the expense
of the forming tubers microscopic
Z examination at this stage viii show
the presence of thousands of club
? shaped conidia in the tissues of the
plant. ne name Early Blight" is
} misleading because its effects may be
most noticeable during the months of
; August and September. It must be
} remembered also that the fungous
does not attack the tubers directly
but the yield results in an inferior
, grade of potatoes, with a high per
! centage of culls.
, quite in contrast to early blight
late blight is caused by an active,
; virulent, parasitic (Phytopthora In
festans) The disease is a native of
, the wild potato vine of South Ameri-
ca and was introduced into Europe,
early in the 18th century. In 1S45
it swept over Germany and the Brit
ish Isles as an epidemic, causing
practically the loss of the entire crop.
Due to its economic Importance in
these countries, the life history of the
fuhgous, as far as it is known, was
early worked out by German and
English horticulturlsts and scientists.
The greatest advance toward the con
troll of the disease has been made In
= this country in recent years, due In
part to the production of efficient
spraying machinery. suitable for
large commercial plantations.
Moist, warm weather during the
months of August and September is
especially favorable for the develop
ment of the late blight fungus Under
these conditions, in two days time,
, the disease may turn an apparently
healthy field into mass of putrefied
and blackened vines. most un-
fortunate feature of the disease is that
it not only destroys the vines, but
the summer spores may gain entrance
to the tubers and cause serious dam
age from rot The rotting of potatoes
in storage. which is very generally
: attributed to the late blight fungous, is
very likely due to bacterial causes.
The relative Importance of the early
: and late blight fungous to the Wiscon-
sin potato industry is not definitely de
termined The loss from early blight
is more steady and it is probable the
r disease does more or less damage
every season. Late blight appears
more periodically, but when it is
present causes more serious damag
to the yield
The success of any commercial
spraying venture depends upon the
+ efficiency of the selected fungicide in
, controlling the disease and upon the
actual increase in profit, which can
T be realized above the cost of treat
ment In New York state several po-
tato growers are cooperating with
the experiment station to determine
the profits under actual farm condi-
tons. A report OF that work for 1905
estimates the cost of each application
at 80 cents per acre. They obtained
an average increase of IS bushels per
acre which netted s22 per acre. Later
reports indicate that potato spraying
has made rapid progress in that state
and is becoming quite general among
the progressive growers.
Probably no spraying consideraticu
Of the horticulturist or gardener can
be accomplished as rapidly, as cheaply
and as efficiently as can potato spray
ing. The machines have reached d
high grade of perfection, making il
possible for two men and one team
to cover thoroughly about 25 acres in
one day. Also, combining a poison
with Bordeaux mixture not only facn
itatcs in controlling the bugs, but
also divides the cost between the two
treatments.
One Of the results Of the potato
spraying agitation win be the intro
duction Of better methods IN fighting
the beetle Serious loss resulted ip
the state last year, due to the clumsy
and careless methods of applying
Parise green These win undoubted-
ly be combined with BordeauXe next
season in Wisconsin for the control
Of the beetle.
Wisconsin is the second state in
the union In potato production. Dur
ing a normal year the crop approxi-
? mates 100000 bushels Last year
that yielu was probably reduced one.
half due to a combination Of the cause
I have mentioned The year proved