Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1915-02-11
Value of Chemicals Against
Weeds In Pineapple Sec
tons Demonstrated

A few months ago the attention OF
, the entire territory was attracted to
the work of Manager c. F. Eckart OF
Olsa plantation in combating weeds
! in the cane-fields with chemical
sprays Now there has appeared a
! bulletin from the Hawaii Agricultural
Experiment station, written by F. G.
Krauss, superintendent of extension
work, which tells of splendid results
obtained on the suppression Of weeds
among pineapples by arsenite of soda
/ spray. -:..
This bulletin says:
The Haiku region on the island of
Maui is noted for its large yield of
| fine pineapples In years of good prices
and normal rainfall the crop is profit.
able one to grow. The season just
closing, however, has been most dis
astrous because of prevailing low
prices, bad roads caused by an I'M
precedented rainfall, and last but by
no means least, an unusual growth of
weeds which it has seemed almost i'm
possible to bring under subsection.
Even in seasons of normal rainfall,
which average about IS inches per
annum, the weed factor has always
been an expensive item in the cost of
producing pineapples. The usual con-
tract price for wedding pineapple fields
in this region is $3.50 per month per
acre, or $50 per annum, for monthly
wedding. At the present time, owing
to the suspension of wedding during
the excessive wet season, growers are
paying $40 to $40 per acre to have
their fields weeded, the average price
being $40. ! ..s..
Under the conditions prevailing in
the Haiku district, no sooner has a
field been gone over than new crop
of weeds appears. In fact, the weeds
are always present. 1t is perennial
fight to keep them under subsection.
Under these conditions any practical
methods of control will be welcomed,
even If they help only partly to solve
the problem. r.. ..
1t was with this view in mind that
the writer began experimenting with
arsenite of soda spray on his home.
stead last June.
Two lots of the arsenite of soda
solution were made up for compare.
tive test, one according to the formula
recommended by the Hawaii Expert
ment station, and the other in ac-
cordance with work done among sugar
cane by C. F. Eckart of Olaa
In the former formula two pounds
of crystal sal soda and one pound
arsenic is boiled in one gallon water
until clear. This stock solution is d.
luted in "a gallons of water in the
field and applied at the rate, rough
ly. of about 100 gallons of the dilute
mixture per acre, more or less, ac-
cording to the length and thickness Of
the growth.
Effective on Grasses.
This has been found effective on
all the grasses and on the Hitchcock
berry on the Nahiku Rubber Com.
papy's lands on Maui. The manager,
w. A. Anderson, reports that it has
not been effective on pualele" (mnk
weed), ginger and wild taro. For best
results on honohono little stronger
solution, perhaps one gallon of stock
mixture to 20 of water, is necessary.
Further on Mr.. Anderson says: "Hilo
grass is actually disappearing from
our fields that have been plowed, and
thereafter, treated with the spray, con-
siderable areas are free from it.; it
has been thinned out everywhere"
Our experience with this spray has
been fairly effective. With us it quite
effectively destroyed the young pua-
Ill nd
it ineffective. The so-called water
grass (Kyllingia breyifolial which is
one of the worst weeds the Haiku pine
apple grower has to contend with, es-
pecially during wet seasons, was but
slightly affected, as well as some other
weeds, notably the honohono, but even
these succumbed to a second or third
spraying when all conditions, especial
ly that of the weather, were favorable.
1t will be noted that Mr.. Anderson's
normal spray solution contains about
four pounds arsenic per 100 gallons,
but that he recommends about five
pounds for best results on honohono.
One hundred gallons of spray are
usually used per acre.
The first spray used by Mr.. Eckart
on Olaa Sugar Plantation, Hawaii, is
substantially the same as far as the
amount of arsenic is concerned as that
used by Mr.. Anderson at Nahiku Rub
Der Plantation on Maui. Both regions
are characterized by heavy rainfall.
The Olaa stock solution consists of
20 pounds white arsenic, four to five
pounds caustic soda, and 10 gallons
water. This is boiled for 10 to 15 min
utes. Two and half gallons of this
stock solution are diluted to 100 gal.
Ions with water. Thus it will be seen
that 100 gallons contains five pounds
arsenic. But only about one pound
of caustic soda is used at Olaa against
about eight pounds crystal sal soda as
used at Nahiku. Theoretically the
caustic soda would be about three
times as efficient as the sal soda.
Effect on Operator.
In the experiments among pineap-
pies at Haiku, both sprays gave sub
stantially the same results, which were
as noted above. However, the main
drawback to both these sprays, espe-
cially where the excess Of caustic soda