The Maui news. [volume] (Wailuku, Maui, H.I.) 1900-current, 1919-05-02
Insure This Years
Irish Potato Crop
II Can Be Done AT Light Cost Blu. Is
Something That Cannot Be Put OF
Till You Happen To Feel Like It
Prof. krauss Tells How


In submitting the following paper
on protecting Irish potatoes from wilt
and various pests, Z. G. Krauss, direc-
tor OF the Hawaii experiment sub
station, at Haiku, says-"I know of
no p~recaution that should be urged
upon our small farmers at this time
more forcibly than this matter of
spraying their potato crops. The
asses due to late blight have easily
run into thousands of dollars each
year. l therefore trust that you will
see fit to give it publicity.
Will you please say that practical
demonstrations will be given at the
sub-station to all interested."-Ed)
Potato growers on Maui, or else
where, continue to suffer serious loss
es on their crops through a~voidable
causes. At the Haiku Satisfaction eX-
periments carried on for the past
three years have shown that the late
blight, mites and aphis, either any
one alone or several in combination,
may totally destroy an otherwise
promising crop, unless guarded
against by seasonable spraying.
That such spraying will prove a
very profitable practice if done sys-
tematically and thoroughly, has been
proved over and over again. In a
cooperative spraying experiment in
the Makawao district in 1917. an in
creased yield of 76 bushels, value at
$114.O0 per acre was obtained from
an outlay of less than $4,000 for labor
and material. In a variety test at
the sub-station in 1918 a section of
each plot was left unsprayed. The
test variety yielding at the rate of
24O bushels per acre where sprayed,
was almost a total failure in the I'M
sprayed section. Another crop of 8
acres yielded only so bags of small
tubers due to non-availability of
spraying material. The loss in this
case, as demonstrated by a small
portion of the field which was ade-
q~uately sprayed, was conservatively
estimated at 500 per acre.
Materials for preparing the Bor-
deauX-mixture, the specific for late
blight on potatoes, so prevalent on
Maui can now be bought locally in
any quantity. Below we give the
formula for preparing Bordeaux mix
ture.
To make 100 gallons of the solution,
sufficient for one application to an
acre of potato plants 6 to 8 inches
high: Dissolve 8, pounds blue stone
"copper" sulphate) in eight gallons wa
ter. This is best done by suspending
the blue stone from a barley bag
placed in the water without touching
the sides or bottom of the container.
The container should be a wooden
barrel, since metal is cOrroded.
In another container Stake 8 pounds
best quality quick lime. This gives
the stock solution which may be
kept indefinitely. When ready to use
the spray, the blue stone solution and
milk of lime are poured together into
a third container of 100 gallons
capacity. The mixture is then made
up to 100 gallons by simply adding
water and agitating to keep the in
soluble matter in suspension. The
mixture should be used the same day
it is made up.
In spraying use a high pressure
spray pump and a fine nozzle. The
plant must be sprayed thoroughly.
the under sides of the leaves must be
reached as well as the upper. But
only a thin coating is necessary,
liquid that runs off is lost and this
can only be avoided by using a fine
mist-like spray.
Begin spraying the young potato
plants when they are about 6 inches
high, and select a dry warm day,
Spray every 10 or II days to protect
the new growth of the foliage. Ii
insect pests are prevalent such as
cut-worms, add 2 pounds arsenate OF
lead to the 100 gallons of Bordeaux
mixture. If aphis (plant lice) are
present (these may be found by look
ing carefully on the underside of the
l%eaves) add l pound "black leaf 40
(nicotine sulphate) to the 100 gallons
of Bordeaux.
The cost of the above spray solu
ton suficiS1 for an acre will be
about as follows:
8 pounds blue stone a zoe $3.50
8 pounds lime q 2ht 20
$3.50