The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1906-05-10
POTATO SPRAYING.
It's Efficacy as Shown by Results at New


The proftableness of thorough
spraying to protect potatoes against
fungus diseases and insect enemies
was very strikingly shown in expert
ments reported by F. G. Stewart and
associates of the New York state ex-
pertinent station. The experiments
have been made under the direct
supervision of the station or in co.
operation with growers in different
parts of the state. In general thor
ough spraying with Bordeaux mix
ture was very effective against blight,
rot and hea-beetle.
While in few cases all loss from
these causes could not be prevented
even by thorough spraying, in every
case where there was a severe out
break of blight enough good was done
to repay all expenditure, both of
money and of time. Generally,
spraying was very profitable. OF
those whose tests were reported to the
station, thirty growers made a net
profit of Sl0, 1000 from spraying.
In fourteen cooperative expert
ments, covering $50 acres, made in
1904, the average increase in yield
due to spraying was 624 bushels per
acre, the cost of spraying was S4.98
per acre, the cost per acre for each
spraying 90 cents, and the net profit
per acre S24.86. Similar and almost
equally profitable results we're OBJ
tanned in six experiments made in
1908.
Not only were there gains in yield
due mainly ''to frightening the time
Of growth by preventing foliage de-
struction by late blight" but the
sprayed potatoes, being more mature,
we're of better cooking quality.
Chemical analysis showed about
one-sixteenth more dry matter in the
sprayed potatoes and one-ninth more
starch. Cooking tests confirmed the
analysis, as the sprayed potatoes were
noticeably more mealy than those not
sprayed, and were pronounced of much
better quality by all who ate both.
The mixture recommended by the
station is Bordeaux of the 1-to-8 form
ula; that is, six pounds of copper
sulphate to so gallons of water, the
acid of the sulphate being neutralized
by about four pounds of good stone
lime. Paris green may be safely
added to thoroughly neutralized
Bordeaux mixture, and this combi-
nation-Bordeaux and an arsenical
poison-has given better results in
station tests than any other fungicide-
insecticide treatment for potato pests.
If thorough spraying is the object,
it would be best to begin when the
plants are six or seven inches high
and to spray every ten days or two
weeks thereafter as long as the plants
remain green. If rain comes before
any application is dry on the vines
the treatment should be repeated, but
spraying should not be stopped be-
cause cit looks like rain.'
In the experiments reported the num-
Der of applications ranged from three
to ten and these were made with ap-
paratus varying in power and
efficiency all the way from fve-gal-
Ion compressed air sprayer carried by
the operator to a power sprayer treat
ing six rows at time and covering
Is acres in day. There was no
fixed relation between make or type of
sprayer and efficiency of protection.
Some homemade outfits gave excellent
results. The essential feature is a
good pump or other source of power,
so that fine spray can be secured;
all other factors are incidental.
If only three applications are to be
made during the season, delay the
first until it is necessary to treat the
potatoes for the potato beetle "slugs. -
Then use the Bordeaux and arsenicals
and spray thoroughly. The second
and third applications should also be
thoroughly made and at such times
as will keep the vines as we'll coated
as possible with the Bordeaux. It is
not safe to depend on resistant va
rieties and neglect spraying. There is
no good commercial variety, so far as
known, that is ''blight proof" and
claims to that effect may be discounted
at once. Some varieties are more
resistant than others, and these
should be selected, other things being
equal, but even these should be
sprayed.
In order to secure general spraying
at the most economical rates the sta
tion suggests that growers arrange
for "public sprayer.
That is, let some one man in the
neighborhood make business of
spraying and secure enough fields to
keep him busy throughout the season.
This plan combines several advant-