Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1915-02-11
ARSENIIE OF SODA spray USED
effectively IN PINEFlELDS


This was boiled Tor about Is min
utes or until the solution was clear
II was then diluted with water to make
loo gallons of solution ready for use.
This amount was applied over approx
nately an acre. OF weedy land having
large proportion OF manienie and
Hilo grass. The results were quite as
effective as with the sprays used by
Anderson, and Eckart, IL 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. Ine 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. So e = ~
The former costs 3h cents per
pound, while the sal soda and soda
ash cost about 2h 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. -, -. ...E
Strength Doubled. ......t
While the use of five pounds of
arsenic per loo gallons Of water APP
piled per acre was fairly efficient in
destroying or at least SURPRISING
most of the weeds encountered, the
water grass (Kyllingia breyifolial as
well as the honohono we're 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 i've 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 (Crotalaria longirostrata),
white wood (Crotolaria war;, pig weed
or purslane tPortulaca oleracea), Ho-
nohono (Cammelina nudiflora), mani
enie or Bermuda grass (Cynodon dac-
tylen) Hilo grass (Paspalum conju-
gatum), water grass fKyllingia breyi-
folia) and the common guaya.
These weeds we're affected in about
the order named. When young, say
from three to six inches tall, most Of
the weeds turn bfown in from two to
three days, the young pualele usually
willis within 10 to 90 hours after spray:
ing, especially when the weather is
bright and warm Should 1t rain with.
in IL hours of spraying the effect may
be nil sof nearly 50 on all but the most
tender weeds. When the weeds were
nearly mature, IT; required fully four
days before the full results were ac.i
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
susceptible to the effects of the arsen-
tie. Of soda, and, 1t was soon found
that every precaution must be taken
to avoid contact.
As the writer is now paying $40 to
$40 per acre to have his pineapples
weeded, the spraying will effect saw
ing of from So to $40 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 y day at $1.50l IS rs
loo gallons spray solution: (max.)
5 to 10 pounds arsenic at 7k
cents ....s....... 10
2h to 5 pounds soda ash at "
cents ........ ............. 81 "
Cost of preparing solution rs
Spraying outfit, interest and de-
probation TN
Total cost of spraying 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 large saving. It is suggested
that the pineapple growers Of dis
trict get together and buy their ma
terials IN original packages at whole
sale.
It should be remembered that this
method of weed suppression is COM
paratively 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-
lated arsenic upon pines growing I'M
der conditions where the weeds are
repeatedly sprayed. A word of warn
ing is. therefore, given to operators to
look carefully for. signs of any possible
injury that might result from the re-
peated use of arsenic spray among
pineapples.