The Hawaiian gazette., 1917-03-27
DISEASES |
Menace IN HAWAII
Practical Methods Of Combating
Them Described BY Fed
,faie eral Experimenters

The presence of numerous potato
diseases in the Islands keeps the acre.
age of Irish potatoes much less than
would otherwise be the case. The
United States experiment station has
under way a special series OF investiga-
tions regarding the most practicable
methods Of combating these diseases.
Any one with diseased fields should at
once communicate with the station a.
II may not be too late to save the
crop by judieiohs spraying. Complete
instructions for spraying and informa.
ton regarding the most satisfactory
types of sprayers can be had upon APP
plication TO the experiment station and
in case any considerable area is affect
ed IL is probable that the station ex-
perts can arrange for spraying dem.
onstration such as was Conducted at
Castner last week and as Is being con.
Quoted in the Kula region of Maui BY
Mr.. Carpenter this week. The recent
heavy rains have caused the late blight
Of the potato to spread much more
rapidly in the fields than Is usually the
case and prompt measures must be 70.
sorted to IL the trouble is TO be rene,
died or held in control.
As general rule the late blight an
pears shortly after the potato vines
come into full bloom, but younger
stands are found to be infected due to
the conditions commented upon. A
potato that Is relatively blight resis.
tant has recently been developed but
the seed stock has not yet been in.
creased sufficiently to make possible
general distribution as yet, and until
disease resistant strains are establish
ed u will be necessary to spray the
biighted plants with such a spray as
the Bordeaux Mixture.
The late blight attacks the under
side Of the leaves first, and unless the
foliage is closely inspected daily, traces
OF its inroads on the vines will not be.
come noticeable until the spores have
penetrated the leaves to the upper
surface causing black or brownish blots
to appear. Examination will reveal the
white fungus spores eneircling the
dead leaf portions, like a mildew.
During such seasons as the present,
| precautionary measures must be re-
sorted to, TO prevent the fungus spores
from entering the foliage. The most
effective of these is to spray the plants
with Bordeaux Mixture at intervals OF
ten days each until the plants have
| attained their growth, the first applica.
tion of the spray to be applied as soon
as the plants have assumed a height
of from six to eight inches. In spray
ing particular pains should be exer
cised to apply the mixture TO the I'M
der as well as the upper side Of the
foliage, and at the highest pressure OBJ
tainable for effectiveness, the object
being to coat the entire leaf surface
with a fine film of the spray, thereby
preventing access of the fungus spore.
70 the leaf cells. About fifty gallons
of the spray are required to spray eff
feetively an acre Of medium sized
plants, as g PC. - w
The mixture is made up of bluestonC
| "copper" snlphate) and unslaked stonC
lime, five pounds each Of the bIueston,
and lime being required to make vi
atty gallons of Bordeaux mixture. II
the potato fields are considerably lesl
than an acre, smaller amounts of thu
mixture may be made up for ten, TWEEN
ty or thirty gallons in proportion I,
the area to be sprayed, as given in tn,
instructions following for mixing VI
ten gallons. a
l. Weigh out one pound Of blueston,
"copper" snlphate). Place in cloth sael
and suspend just below surface O
water in glass jar or wooden containe
containing five gallons of clean water
Bluestone dissolves slowly and it i
advisable to be, left to dissolve owe
night. y, s.E...