The ranch. [volume] (Seattle, Wash.) 1902-1914, 1904-05-15
The Field and Garden
Spraying Potatoes for Blight

growers to take a new interest in
remedies for it's prevention. Of all
preventative measures tested, spray
ing with Bordeaux mixture has proved
the most efficacious.
In summing up results of the test
at the Maine station, Director Chas.
w. Woods, says: "The increased
yield more than paid the cost of spray
ing with Bordeaux mixture. On the
average the yield of the early varie-
ties was one third greater on the
sprayed plots, and in one case of late
varieties, one-half greater than on the
unsprayed."
The New York station entered upon
a ten year test in 1892, and the result
obtained for the last two years lead
Prof F. H. Hall to say: "The potato
grower who sprays thoroughly every
year. insures his crop against serious
damage from blight and rot; and in
seasons when disease is epidemic, will
make enough profit to repay the cost
of treatment for many years. At
Geneva, in 1902, the gain from spraying
three times during the season was
fourty-fve per cent; and from spray
ing every two weeks, fiftysiX and one
third per cent; in 1903 the gains were
fifty and one-half and siXty-eight per
cent respectively, for similar treat
ment." Tests on a larger scale made
for the station by farmers in different
parts of the state showed similar res
ults. The average increase in yield
amounted to siXty-One bushels per
acre. The profit ranged from $23 to
nn1x ;y,D civ,
was there loss, and in that instance
the cost of spraying was needlessly
high and the attack of blight was light
and came late in the season. For
these reasons the increase of seven
bushels per acre did not quite pay for
the spraying.
We are aware that a few growers
have reports that spraying has proved
ineffective against the blight on their
farms, but in the large majority of re-
ports that have come to us, directly
and indirectly, the Bordeaux mixture
has proved effective in either prevent
ing or checking the ravages of the
blight and the rot that inevitably fol-
lows the attack of the fungus on the
leaves.
Spraying to be effective must be
done early often and thoroughly.
From the time when the potato tops
are five or six inches tall the foliage
should be kept covered with the Bor-
deaux. The spores or the seed of
the fungus alight on the leaves and
take root in the leaf substance, just
as clover or grass seed falls and takes
root in the soil. The first evidence
of this appears when the edges of the
leaves turn brown and begin to curl
At this period it is too late to spray
such leaves, for the fungus has emit
cred into the tissues of the plant and
will continue in spite of any fungus
poison that may be put on the surface.
If the leaves and stems are covered
with Bordeaux, the fungus spores will
be killed when they fall on it. Spray
ing is a preventative and not cure,
therefore keep the vines covered with
the prOte ctive fungicide.
The spraying at stated periods, three
times in the season, and again every
two weeks, adopted by the New York
station, is proper for experimental
work, but even the more frequent
Sprayings Of the station may not be
sufficient in certain conditions. The
fungus rarely appears when the soil
is dry and the atmosphere is dry and