Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1915-02-11
ARSENITE OF SODA SPRAYUSED
EFFECTIVELY in PINET|ELDS

This was boiled for about Is min.
.utes or until the solution was clear.
II was then diluted with water to make
100 gallons of solution ready for use.
This amount was applied over approx
mately an acre of weedy land having
a large proportion Of manienie and
Hilo grass. The results were quite as
effective as with the sprays used by
Anderson and Eckart, If not more so.
but this may have been apparent rath-
er than real, as the weather conditions
may have been more favorable in the
latter experiment. Ihe important thing
is that the caustic quality of the new
spray was greatly lessened, and in
this must lay its main advantage. How
ever, there may also be slight saving
in the cost of using the soda ash in
place of the caustic soda or the sal
soda.
The former costs 81 cents per
pound, while the sal soda and soda
ash cost about az cents per pound at
wholesale Theoretically the soda ash
is two or three times as efficient in
combining with the arsenic as is the
sal soda.
Strength Doubled.
While the use of FIVE pounds of
arsenic per loo gallons of water ap-
piled per acre was fairly efficient in
destroying or at least suppresSing
most of the weeds encountered, the
water grass (Kyllingia brevifolia) as
well as the honohono were not ma
terially affected. A second spraying
within a week of the first application
increased the suppression considera-
bly,. This suggested that doubling the
strength of the solution might save
spraying the weeds twice. According
ly in October, 10 pounds of arsenic
and five pounds of soda ash were used
to make up 100 gallons of solution.
This has been very effectively applied
to the. following weeds: Pualele or
SOW thistle (Sonchus oberaceus) rat
tie pod tCrotalaria longirostrata) i,
white wood (Crotolaria var, pig weed
or pursiane (Portulaca oleracea), Ho-
nohono (Cammelina nudiflora), mani
enie or Bermuda grass (Cynodon dac-
tylon) Hilo grass (Paspalum conju-
gatum), water grass tKyllingia BREW
folia) and the common guava.
These weeds were affected in about
the order named. When young, say
from three to six inches tall, most of
the weeds turn brown in from two to
three days, the young pualele usually
wits within 10 to 20 hours after spray
ing, especially when the weather is
bright and warm. Should it rain with
in IL hours of spraying the effect may
be nil or nearly so on all but the most
tender weeds. When the weeds were
nearly mature, IL required fully four
days before the full results were &C.
complished. While the honohono, wa.
ter grass and guava were not wholly
destroyed in any case, they were sup
pressed to an extent that proved OF
great economic value. ">
Naturally, the spray affects all plant
life with which it comes in contact.
The pineapple is apparently unusually
to the effects of the arsen-
lite of Soda and it was soon found
that every brecaution must be taken
to avoid contact. ....h.> =.
AS the writer Is now paying SO to
$40 per acre to have his pineappies
the spraying will effect a saw
ing of from SIS to SO per acre less
the cost of spraying. %..:..". ...>...
The cost of spraying per acre as
now practised is about as follows:
Labor of spraying one acre of "
pineapples az day at $1.50)..$ rs -
loo gallons spray solution: (maX)
5 to 10 pounds arsenic at IN
cents NEUTRALITY-SUSPICIOUS.. 10
21s to pounds soda ash at w
cents -. ........:......... .37k
Cost of preparing solution. 49,. .25
Spraying outfit, interest and de-
probation .................. 17k
=. 90 -t' --.
Total cost of spraying 1 acre. $3.50
The materials used in the spray can
be bought, at wholesale, for about one
third the prices given above. thus eff.
fecting a large saving. 1t is suggested
that the pineapple growers of a dis
trict get together and buy their ma
terials in original packages at whole
sale. - <.~. .:a.:'. >@-@
1t should be remembered that this
method Of weed suppression Is com.
new. In so far as the
writer is aware, arsenite of soda spray
has not been used among pineapples
except in the demonstrations here re-
ported. 1t is, therefore, not yet known
what may be the effects of accumu-
ated arsenic upon pines growing un-
Ter conditions where the weeds are.
sprayed A word of warn
ng is, therefore, given to operators to
ook carefully for signs of any possible
injury that might result from the re-
Deated use of arsenic spray among