The Hood River glacier. (Hood River, Or.) 1889-1933, 1905-02-09
PARIS GREEN
BURNS LEAVES
EXPERIMENTS IN PAJARO VALLEY
Aasenate of Lead Combines killing
Properties with Neutral Fleet
on Foliage.

Valley OrchaFdists Association EntO
mologist w. w. Volk gave review o
his Goblin moth Investigations. Tn,
following is synopsis of what he sale
on the subject, as reported by tn,
Watsonville Pajaronian:
| first took up the work of the cod
lin moth investigation in the middle
of the August last year. At that tim,
the injurious effects of too heavy
use of paris green had begun to bt
manifest in certain orchards. The
seriousness of this condition was
quickly realized by those in charge Of
the Investigation. and Professor Wood.
worth directed that a special study be
made of the problem at once Work
was begun early in September and a
large number of small experiments
were made and nearly all of the known
arsenicals were specially tested with
regard to their effect upon the foil
age. Counter experiments we're also
run to determine their value as in
secticides, These experiments result
ed in very quickly showing that under
the climatic conditions prevailing in
and around Watsonville of the So
called insoluble arsenic compounds
we're liable to break down and iberate
the arsenic in soluble form, in which
case it can readily gain access to the
leaf and bring about the poisoning
and killing of the tissue, known as
| burning.
The substances experimental with
were, i'll the main, the ked2ie formula,
paris green, arsenatc of lead-homo-
made and commercial varieties. All
of these compounds proved injurious
except the arsenate of lead and Dis
parine, a commercial form Of lead
arsenate, which proved the best of all,
not injuring the delicate foliage of
beans when applied in the greatest
possible concentration.
The addition Of lime was also made
point of study. 1t was found that
this retarded the injurious effects of
paris green hen added in moderate
amounts, but the small experiments
did not indicate that the excessive
use of lime brought about any marked
injury prevention. these results do
not agree with exactly the practical
spraying done in Oregon and to some
extent in the valley.
1t has long been known that the ad-
dit;on of lime tended to prevent in
jury from Paris green, and in theory
it las supposed 70 act chemically ON
the uncombined OF free arsenic aud
thereby fo"ll an i.htoluble arsenite of
lime. But on closer study il was seen
that the white arsenic, or suluble ar
senous oxide, which was supposed to
be the cause of all the injury, could
not be readily combined with the lime
in this manner. 1t was also dis
covered that the paris green itself
would break down some days, weeks
or months after the application, ac-
cording to the weather conditions and
the stability Of the product, Then
the chemical combination Of the lime
with free arsenic can hardly account
for its action in preserving the paris
green particle, 1t seemed then that
another cause must be sought for
Every one has observed that bucket
of lime water will form a skin over
the surface after standing few hours
This skin is lime bicarbonate and is
formed by the action of the carbonic
acid gas IN the air on the lime solu-
tion. The carbonate of lime is nearly
inscluble and so skin of it quickly
for ms at the surface Of the water.
This same skin is formed anywhere
a Iarticje of lime solution is exposed
A glass plate vet with lime water will,
as soon as The water has eVapOrated
be covered vita tenacious skin OF
lime carbonate. The same thing hap
pens with particle of paris green
wet with lime water. This skin is
nearly insoluble i'll water and is also
quite resistant to weather decOmposi-
tion and hence acts as a protection to
the particle. But so far nothing has
been found which will improve the
weather resistance of paris green as to
make it safe in the Paiaro valley
1t is safe for the reasons above stated
that we were forced to give up paris
green and substitute lead arsenate
which, in the earlier experiments,
was found to be the safest of all ar
senicals tested.
The small experiments of last sea
son were supplemented this year by
some on larger scale, a short ac-
count of which will not be out of
place here.
Such experimental work as was car
ried on in the field was conducted at
the Rodgers place on Lake avenue.
G. II. Rodgers kindly gave Us the lib
erty of the premises and stood such
expenses last we're conducted with the
work in the field.
The field work consisted Of three
principal spraying experiments, sup
plemented by number Of smaller
ones. In the principal experiments
the spraying was done with a power
outfit One set Of trees was sprayed
with the oil and paris green mixture.
the formula being changed somewhat
from time to time. The first spray
ing consisted Of 10 ounces of paris
green, 3 pints Of linseed oil and 6
pounds of lime in 30 gallons Of water.
The application was made on the 2lst
of June. At the time of the applica-
tion the foliage was in good condi-
tion. One month later, or at the time
of the second application, there was
a slight, through noticeable, injury
to the foliage.
In the second application l3 ounces
of paris green we're used, with 3
quarts of oil and 8 pounds of lime.
Only half the trees we're sprayed the
second time. the injury which was
just apparent at the time Of the sec
ond spraying developed slightly more,
and then was apparently checked,
so that at the time of the third appli-
cation, August q, it seemed to he less
seriously than formerly.
The formula used in the third spray
ing was consisted of paris green 10
ounces, linseed oil 3 quarts and lime
s pounds Shortly after this spraying
the trees lost heavily and at the time
of the hot spell in September many
leaves yellowed and fell, leaving the