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Ernest Hart

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1914

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THE DEVELOPMENT OF IMPROVED
DUSTING MACHINES AND DUSTING MATERIALS

by

ERNEST HART.
1914

May 1, 1920.
THESIS
THE DEVELOPMENT OF IMPROVED
DUSTING MACHINES AND BUSTING MATERIALS

To obtain a clear understanding of the
problems met with and the difficulties overcome in devel-~-
oping improved dusting machines and materials for the
control of orchard pests and diseases by the application of
insecticides and fungicides in the form of dry powders, a
brief review of the history of dusting up to 1914 seems
necessary.

For considerable length of time,the grape
growers of France, Spain and Italy had been uftlizing
the dusting method for the protection of their vineyards
against insects and diseases. The method of application
of the materials, which was called "sulphuring" was very
crude and therefore not entirely efficient.

In the southern part of our country, dust-
ing had been in vogue for & considerable period, as a means
of applying poisons such as Paris Green, London Purple,étc.,
to tobacco, cotton and similar crops. Here, the applica- —
tion of the dust was usually accomplished by the "bag and
pole" method which consisted of shaking a pole carried between
two horsemen riding opposite each other, so that the material,
by the shaking action, would be sifted through the muslin sauzks
or bags which were hung to the pole directly over the rows.

Orchard dusting had been in limited use and

had been the subject of considerable amount of experimental
work during a period of at least twenty years. The gachinery
used was either hand operated of of a very crude mechanical

~l-
96913
type securing its power from a small gasoline engine.

About 1910, much enthusiasm was mani-
fested over experiments conducted in Illinois and elsewhere
with & crude powdered form of Bordeaux Mixture, Bordeaux at
this time being widely used as a liquid spray. On account
of inadequacy of the machinery for making the applications,
and the crudeness of the dusting materials used, these very
promising experiments soon lost favor and the wave of dust-
ing enthusiasm soon died out.

In 1914 and 1915, the writer was closely as-
sociated with the Cornell Experiment Station workers in
their now wellknown series of dusting experiments, at the con-
Glusion of which, in 1915, they stated that, even with the
inadequate machinery and crude materials used; "it now seems
wettled that a mixture of an insecticide and fungicide can
be applied in the powdered form, using the air as a carrier
with better commercial results for the control of preventable
apple diseases and of apple insects than can be obtained by
spraying. At the same time, the dust method makes it possi-
ble for the owner of a large acreage to protect his orchard
at critical times, a thing he has not been able to do with
the slow liquid process".- Cornell Bulletin 369, New York
State Experiment Station.

It should be noted that Sulphur was used as the
fungicide for controlling Apple Seab instead of Bordeaux
Mixture. The idea of using Sulphur originated from prev-
ious successful experience of the same investigators with the

use of Sulphur against Hop Mildew in the hopyards of New York

fe
State.

The officers of the Niagara Sprayer Company
of Middlepért, N. Y., with whom the writer is and was -assoc-
jated at that time, were firmly convinced that the dusting
method as worked out by the Cornell dxperiments could be im-
proved and perfected go as to make the proposition a thor-
oughly practical commercial undertaking which would find
ready favor with large users of insecticides and fungicides.

The factors determining this conviction were
largely:

First: The success of the dusting experiments,
which clearly indicated that Sulphur in the dry form Was as
effective as Sulphur in the liquid form.

Second: Increasing trouble on the part of
the growers in securing enough and efficient labor to op-
erate liquid spraying equipment.

Third: The speed and ease with which the
dusting operations could be accomplished by the average or-
chardist.

Fourth: The elimination of dependence on
water supply.

Fifth: The evident simplicity and complete
reliability of dusters as compared to liquid aprayers.

Sixth: The lightness of dusting equipment
in the matter of weight and draft.

Seventh: The large acreage possible to
cover in short periods of time thus making possible, timely
applications over large acreages for the control of Apple Scab.

Eighth: The fact that ordinary farm help

adja
are opposed to the operation of liquid sprayers while it
was considered by those who hag used the method that dusting
as compared to spraying was an almost "pleasant" operation.

Sulphur being the most successfui dust fung-
ioide, and being the bagic material of all the successful
dusting mixtures, was naturally the first material to re-
ceive attention. |

Apples and peaches being of principal com-
mercial importance in the sections then becoming interested
in dusting machinery and materials, these two fruits were the
subject of the first investigations.

Previous laboratory and field experimentation
with the Apple Seab disease by Experiment Station Experts as well
as the writer, determined beyond question that the fungicidal
properties of Sulphur dust were practically directly proportional
to the physical fineness of the material.

It was quite definitely determined that pure
Sulphur of a physical fineness sufficient so that 95% woulda
pess through a screen having 200 meshes to the lineal inch,was
comparable in fungicidal properties to ordinary lime-sulphur sol-
ution then in general use. Other important factors also determ-
ined the necessity of a 200 mesh Sulphur dust. They were:

First: Distribution and Covering Qualities:
Thoroughness of distribution and covering qualities being para-
amount in the fight against Apple Scab infection,it was quickly
seen by field experiments that a much more even and uniform
covering could be accomplished by the use of the smoke-like
Sulphur cloud than could possibly be accomplished by

coarser grades of materials.

ohLea
The reasons for this are obvious.

Second: Adhesiveness and Sticking Qualities: The
treatment with dust for fungicidal purposes being almost wholly
& preventative measure made the factor of sticking aualities
& highly important one. Field demonstrations showed at once
that Sulphur of less than 200 mesh fineness would not adhere
well to the fruit and foliage while 200 mesh material actually
stayed onthe trees longer than liauid sprays especially,
if applied under conditions that

NIAGARA SPRAYER COMPANY

EXPERIMENTAL ORCHARD fia

WE INVITE COMPARISON OF QUALITY-FRUIT

T &FOLIACE
WITH ANY SPRAYED ORCHARD IN WESTERN NEW YORK
" CO ;

weir? Deo. —
Ve ‘

 

 

allowed the dust to*"set". These conditions were prought
about by dews or light rains following within a few hours

after the applications. This factor was responsible later

-5- :
for the recommendation that the dust be applied in early
morning or late evening so as to take advantage of the damp
conditions then likely to prevail and thus secure the "set"
which seemed desirable for adhesiveness.

Third: Economy of Materials: Experiments with
materials of various finenesses showed that 100 pounds of 200
mesh Sulphur would give a thorough coating on about 50 average
size apple trees while sulphur of 150 mesh fineness would give the
same covering on only about 30 trees.

For this reason, if no other, 200 mesh Sulphur
became a necessity in the matter of economy of materials.

From these principal reasons it will be seen
that our problem was to produce a pure Sulphur having sufficient
fineness that 95% would pass through e 200 mesh screen.

To begin with, the finest Sulphur dust of ordinary
commerce at that time was but 80 mesh and no manufacturer had pro-
duced any finer product than this in commercial quantities, as
far as could be learned.

Special machinery was designed and various equip-
ment experinented with for 2 years in an effort to produce this
material. Progress on the problem was continuous but interrupted
by many disappointments and losses due to explosions, spontaneous
fires and every manufacturing trouble imaginable.

In 1916, however, in spite of all of the
trouble experienced,200 mesh Sulphur was produced in commercial
quantities and sold for orchard dusting purposes and each

year following, successive gaing were made in the

aha
 

 
 

 

quality and fineness of the product. Briefly, the system
of manufacture finally hit upon consisted of a series of
successive grindings, each reducing the material a little
finer and finally separating the fine from the coarse par-
ticles by means of air separation which automatically di-
vided the product into various grades of fineness of which
200 mesh material was used for dusting purposes. Danger to
life and property in the process has never been completely
overcome due to the explosive nature of the Sulphur dust when
confined under certain conditions.

The perfection of 200 mesh Sulphur dust gave
8 decided impetus to the dusting method and excellent results

were at once secured by commercial orchardists who used the

a
material. Experiment Stations in all parts of the country
where fruit is grown began to work with dusting and the U. S.
Department of Agriculture undertook a number of investiga-

tions in various fruit growing sections.

KU

 

Poisons such as Paris Green and Lead Arsenate had
been used for sometime as a direct application by dusting and it
wes not difficult to secure the production of an extremely
fine powdered Arsenate of Lead with physical properties somewhat
similar to the Sulphur. The matter of fineness and cubical
density of this material held none of the unknown or difficult
problems encountered with Sulphur and a suitable poison to

use in dusting work was quickly produced. Free

-8-
arsenic or water soluble arsenic being detrimental for direct
poisoning purposes, this content of the Arsenate of Lead for
dusting purposes, was reduced to the lowest possible minimu,
With the result that practically no arsenical injury resulted
from the use of the material even in excessive quantities, on
apples.

On account of the necessity of using combined
applications of both fungicide and poison, the same as was
in vogue in liquid spraying, the problem of suitable
mixtures were next attacked. The combinations used in the
early work by the Cornell Experimenters were mixed on a board
or in a barrel by means of a shovel and in one or two cases,
an ordinary cement mixer was utilized for this purpose.

The first mixtures used in the Cornell experi-
ments consisted of 50% Sulphur, 10% Arsenate of Lead and 40%
filler, (in this case Gypsum). Later field experiments as well
as commercial experience clearly demonstrated that on apples at
least, the use of a filler was undesirable as it did not mat-
erially accomplish its object, namely, to reduce the cost of the
mixture ,but did interfere to some extent with the proper fune-
tion of the Sulphur. In other words, pure dusting mixtures
containing no filler gave better commercial results than
mixtures containing fillers.

Our experiments over previous seasons had prov-
en that 90 parts of Sulphur and 10 part of Lead in the mixture
had given excellent results. No better results were secured
with a mixture containing 15% poison, yet, it was thought wise
to recommend the latter mixture to orchardists who were just
beginning the dusting work as this at least would insure a

=In
full measure of poison. Largely for this reason, the 85-15
Mixture was most popular at the outset of the dusting work but
it is now almost entirely replaced by what is termed the Stan-
dard Apple Mixture, namely, 90-10.

The success of the 90-10 Mixture on Apples
led to its application on Peaches and other fruits. Exper-
ience and experiments here however, soon showed that a cer-
tain element of danger to Peach foliage existed in the arsenic
content of the material and so, 10% of Hydrated Lime was add-
ed to the Mixture to neutralize this possibility. 80% Sulphur,
10% Arsenate of Lead and 10% Hydrated Lime, known as the 80-10-10
Mixture may now be termed the Standard Peach Dusting Mixture.

The commercial production of these Mixtures in-

volved a number of problems which had to be overcome before

 

-10-
the product could be marketed. Special machinery for
mixing the various materials was designed and after a consid-
erable period of factory experience, homogenously mixed and
therefore dependable mixtures were produced,

It may be readily seen that disaster would re-
sult if materials were improperly mixed. as, one tree might re-
ceive all the Arsenate of Lead, and another tree ail Sulphur and
vice versa. Other problems to be overcome in mixing were the ob-
taining of materials and fillers of nearly equal fineness and
neerly equal specific gravity so that a separation would not
occur when the dust was blown from the machine into the air.

In 1916, the perfected mixtures of Arsenate of
Lead and Sulphur were marketed and excellent commercial results
were secured. This again gave further impetus to the method.

Dusting, by this time, had gained a great com-
mercial momentum and the demand became very urgent for a matar-
ial that could be used in the Mixtures as a contact insecticide
against such sucking insects as Pear Psylla,4pple Aphis, Red
Bug , eBc.

To meet this demand, manufacturing experiments
were begun upon the grinding of tobacco stems to a powder have
ing 200 mesh fineness. In a few weeks the desired product was
produced and field experiments on Aphids and Pear Psylla were
then begun. These covered a period of two years.

Tobacco stem dust was used experimentally in
three distinct manners:

‘Pirst: The clear Tobacco stem dust.

Second: The simple mixture of 50% Tobacco stem
dust and 50% Sulphur.

-ll-
Third: A mixture of 50% Tobacco dust, 40%
Sulphur dust and 10% Arsenate of Lead.

All three of these materials proved to be effect-
ive against the sucking insects involved in the field exper-
iments namely, Apple Red Bug, Green Aphis and Pear Psylla. At
the conclusion of the experiments, the combined mixtures

containing Tobacco dust for contact insecticide were placed

 

r ts 1 iy d

on the market and met with a large demand. Unfortunately, varying
results were secured by commercial orchardists in the matter of
effectiveness and these materials again came under close investi-
gation. Observation of results secured together with laboratory
analysis of the tobacco dust gave the solution of the trouble,
namely; the nicotine content of the Tobacco stem varied so greatly
that a uniform and homogeneous nicotine content in the mixture

was not possible.

The next logical step seemed to be to make a ma-
terial in which the nicotine content could be controlled ac-
curately. Black Leaf 40 or Nicotine Sulphate had proved so
effective a contact insecticide in the liauid form that the
possibilities of this product were first investigated with
the result that laboratory and factory tests showed that

Nicotine Sulphate could be impregnated into Sulphur to pro-
akee
duce a known and constant nicotine content of as high
as 2% while the highest average nicotine content of the
best Tobacco stems was but one-half of one percent. By
adding a small percentage of Plaster Paris to the mixture
to assist in drying, the material retained its fluffy fineness
and was entirely suitable for dusting purposes.

This new product was placed under experiment-
&l field conditions at once and also given out to a number
of commercial growers where it was used under supervision.
Excellent results were secured and thus the various mater-
ials required for the summer treatments of Apples and Peaches
seemed complete. An excellent fungicide, Sulphur, could be
combined with an excellent stomach poison, Arsenate of Lead
and when occasion required, a strong and effective contact
insecticide, Nicotine could be added.

By the time developments in the method had
reached this stage, many commercial orchardists had replaced
worn out liquid spraying equipment with dusting machines
without giving thought to the matter of dormant applications
to the apple orchards for the control of San Jose scale.

While in most principal orchard sections, the
San Jose scale had been largely sradicated, the problem of
furnishing duster users with materials suitable for dusting
which would control San Jose scale, became so acute that in-
vestigations were at once begun with various chemicals to
locate something that would answer the requirements. Sev-
eral powders known to be effective against San Jose scale when
used in the form of solution, were tried out without effective

results.

Finally, however, after a series of difficult
ol13-
factory experiments in the matter of grinding to sufficient
fineness for practical use, a very fine sodium polysulphide
was produced which, when mixed with 25% of inert filler
(Hydrated Lime), gave an excellent dust from the point of view
of physical properties.

This material was not deliquescent when in
massed form but when biown out of the machine in a fine smoke-
like cloud, especially on damp days, the tiny particles of
sodium polysulphide turned to a semi-fluid and readily stuck
on the dormant trees even of smooth bark. Large trees were
effectively covered by dusting from two sides only.

Careful check proved that 98% control was se-
cured on infestations which were very serious in two of the
experimental orchards. Commercially, the material has been
widely used, in a small way, by growers who had fundamentally
clean orchards with reference to San Jose scale but who wexper-
ienced minor infestations in certain small areas of the ore
chard from time to time.

The development of this dormant dust obviated
the necessity for both liquid and dust equipment and was very
instrumental in leading to the adoption of the new method by
many growers who could not see their way clear to own and oper-
ate both the liquid spraying and dusting machines.

Such diseases of Apples as Bitter Rot and
Apple Blotch whééh have not been considered to be suscept-
ible to Sulphur treatments either in the liquid or the dust

form heve come under consideration during the past two years.
Bordeaux Mixture liquid, being effective against these diseases

it was determined to begin a series of experiments to ascer-

w~1l4a
tain whether Bordeaux powder of 200 mesh fineness would not be
equally effective as a dust.

Orchards were selected in Virginia where both
of these diseases are prevalent for this work. Experiments
were conducted with a mixture containing 25% powdered Bordeaux
Mixture which contained in turn, 11% metallic copper. ‘The
results secured were negative but clearly indicated that a
stronger Bordeaux powder would give effective results.

Field experiments are now in progress with a
powdered Bordeaux Mixture of 22% metallic copper content and
also with a mixture containing dehydrated pure copper sul-
phate powder. Should these series of experiments prove
successful, which they undoubtedly will, dusting will have
been made a complete substitute for liouid spraying for
practically all of the preventable Apple and Peach diseases

and insects.

 

   
  

 

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In 1914, when experiments on the improvement
of Sulphur were begun, work was also started on the design
of a suitable dusting machine for applying the fine mater-
ials properly and thoroughly to the trees. All types of
existing machinery for dusting purposes were secured and
experimented with under field conditions, in one of the ex-
perimental orchards.

The whole season was spent in this work and
the experience offered many suggestions for overcoming known
weaknesses in the dusting machines and adding refinements
to the design of the proposed new machine.

Summing up this field experience with handling

the available dusting equipment in 1914, it became apparent
that all existing types of dusters were entirely inadequate
to meet the situation and that in order to be successful
in handling the materials then in process of production for
dusting purposes, a practical dusting machine must at least
embody the following general features:

First: An outfit for dusting should be light
in weight yet sturdily built and absolutely reliable, so de-
lays at critical periods would not be experienced by the
nedessity of repairs and adjustments. Extra strength of
constructién was also considered essential because the dust-
ing machine would be subjected to rough usage by the fact
of its being drawn more or less rapidly over rough orchard
land While in full operation.

Second: It should have a hopper of sufficient
capacity to hold at least 100 lbs., of the finest dust and
should be provided with a dust-~-tight cover sufficiently
large to allow the mouth of the bag of material to be intro-
duced directly to it for filling purposes so as to avoid
waste from spilling or loss of material by secondary transfer
from containers into the hopper.

Third: It should have a feeding device which
would give an even and steady flow of materials and which
would be susceptible of very fine and accurate adjustment
by the operator so that the amount of materia applied might
be easily regulated.

Fourth: A provision should be made for break-
ing up the tiny "balls" of Sulphur and other materials before
the dust leaves the discharge pipe. The "balls" are formed
by a mass of tiny particles clinging together and are easily
broken up by alight crushing. If the dust were allowed to
be thrown out of the machine without breaking 211 of these

as in the case of all machines tested, great
-17a

tiny"balls"
waste of material would result and the "balls" would roll off

the foliage without sticking, thus resulting in an irregular
distribution.

 

Fifth; It should be provided with a fan
for producing the air current which would give a sufficient
blast to carry the dust to the highest trees and yet require
& minimum of power to rotate it in order tokeep down the
weight and size of the necessary power plant. Bearings for
such a fan should be of a type that would allow of at least
2500 revolutions per minute with a minimum of attention to
lubrication.

Sixth: A clutch or similar device should be pro-
vided to allow the duster to be disengaged from the powr plant so
that the hopper might be replenished without stopping and start-

ing the engine.
-18<
These six principle features then, were found
by field experience to be essential to a successful dusting ma-
chine and experiments were begun with various devices to accom-
plish the perfection of a machine embodying all of these features.

None of the machines which Were available had
any of these essential features even in a half successful way
so that practically all of the final results in improved dusting
machines Were accomplished by shop experimentation and field tests.

The first improved duster produced for con-~
mercial purposes had all of the features considered to be
essential to a successful dusting machine and Wes. a marked
improvement on all existing types.

First: The machines were light weight; weighing
only about 700 pounds with engine complete. They were simple
and built of the best materials obtainable and hence were
reiiable. For example, all bearings were made of babbitt met-
al except the fan bearings which were made of the best bearing
bronze while the previous types of dusters carried nothing
but cast iron bearings.

The machine was mounted on a three point
suspension principal as low as possible and thus elimin-
ated at once the danger of disalignment of the warious working
parts by twists and strains while in operation.

Second: The hopper had sufficient cubic
capacity for holding one hundred pounds of the finest dust
and the opening for filling was amply large. The hopper wag
dust-tight in every Waye

Third: The feed was accomplished by means of &
 

 

 

 

ae = A—Hopper G—Feed Control Lever.
a H—Agitator Brushes.

 

 

ge . a eo B—Hopper Cover.
= C—Fan Case. i
Ber D—Fan Runner. J —Countershaft

et E—Belt Idler. K—Air Chamber

B= F—Skid.
ee
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ee
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DIAGRAM OF IMPROVED DUSTER

revolving cylinder of brushes which forced the material
through a perforated plate thereby crushing all lumps before
the dust finally fell into the air chamber at the bottom of

the hopper.
Beneath the perforated plate at the bottom of

the hopper was a feed regulator consisting of two diagonally
slotted slides working over each other. The position of the

slides was controlled by a small hand lever conveniently locat-
The op-

of

ed at the end of the hopper near the discharge pipe.
erator was thus permitted to regulate the amount
The plate and slides were made of a

-20-

material to be discharged.
metal which would resist the corrosive action of Sulphur and
other chemicals which were used for dusting purposes.

Fourth: The fan was constructed of aluminum
metal giving great strength and lightness and the bearings were
designed of the self-oiler type same as used on high speed
electric motors. They were made of the best bearing bronze
and were enclosed in a housing which was absolutely dust-tight.
These bearings, it will be readily seen, required a minimum of
attention in the matter of lubrication.

Fifth: An expansion band clutch was provid-
ed which allowed the engine to be disengaged when necess-
ary, such as in driving from place to place, changing
position, refilling the hopper, lubricating, etc.

The first improved dusters were so light and
simple that it was considered that one horse could draw the
outfit, therefore, the equipment consisted of shafts instead
of a pole. The larger types of machines designed later,

however, required the use of a team.
k \ ,

  

~-Lle
and for this reason, the single hitch was entirely discontinued.
The manner of mounting machines on the

wagons was a problem which passed through many varying stages

of development. First the duster was mounted in front on the

wagon and the engine next to the operator who was on the rear

and who was protected by means of a railing about waist-high.

This idea,was, of course, descended directly from the old

spray towers. This arrangement was quickly improved

as it was evident that with the operator on one end

     
    
 
 

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6f the wagon and the duster on the other end, the flow of
materials could not be regulated conveniently. The railing
guards were also found to be entirely unnecessary. Therefore,
the dusters were next mounted by placing the
engine ahead of the duster but in order to

«22a
accomplish this change, it was necessary to introduce a
countershaft on the machine. The railing was discontinued
and the long flexible rubber hose was replaced by sheet metal
pipe about six feet long, connected to the duster by means

of a short flexible piece of rubber and wire coupling.

 

The dusting method now was meeting with

such favor that many orchardists having large commercial
acreages of matured trees were adopting the method, and they
demanded a larger and more powerful type of outfit. There-
fore, the discharge pipe was increased to four inch diame-
ter instead of three and the fan capacity was trippled. This
type of high power duster met with immediate success and is
now the standard size machine for general dusting work.

A few mechanical refinements were added to
the dusters each succeeding year, but the only important
new development after 1918 was the adoption of the drop

platform idea in mounting the outfits. Trouble had ale
~23-
ways been experienced by orchardists in being brushed off of
the machine by lowhanging branches and in many orchards, the
problem seriously interfered with good work. By dropping the
operator's platform on the rear of the machine, down below
the platform of the wagon, this objectionable feature was
practically overcome and better applications were generally

made because of the greater freedom and ease of the operator.

be

=

nae oe "11s

 

After the commercial success of the
dusting method had become assured, variations in the
standard machines were made, to meet different spec-
ial conditions brought about by the treatment of such
crops as Strawberries, Potatoes, Cabbage, Tomatoes,
Ornamental Shrubbery, Gardens, Cotton, Tobacco, Walnuts,
Parks and Shade Trees, Citrus, etc., by the dusting
method. The mention of a few of these adaptations which

were accomplished by field experiments will typify

the many which have been made for all the various kinds
a2he
of work in which dusting has been found to be successful.
The dusting of Strawberries, Potatoes and
similar rowed crops, on @ large scale, made it nec-
essary to develop a distributor for the dust which would
place the discharge of the material directly over the
rows and allow several rows to be treated at one time.
It was also necessary to discharge the dust close to the
plant to obtain the desired results. A distributing
system was devised for this work consisting of three to
five individual nozzles hanging from the rear of the ma-
chine and connected to the main discharge by rubber tub-
ing and galvanized metal pipe. The device worked per-
fectly under field conditions.
A slight refinement was added to this dis-
tributor when the cotton dusting machines were developed by

making it possible to raise and lower the nozzle from the

driver's seat by means of a hand lever.

 

bpd cae eG e Mexcate ahs aeg tate ma Mie ee TE,

-25@
To meet the demand for a hand operated duster,
of about similar capacity to the wellknow barrel spray
outfit, for the treatment of Small Trees, Truck Crops, Cab-
bage, etc., where a large power machine would not be nec-
essary or practical, "the blower gun" was developed in
1918. The "blower gun" embodies all of the essential
features of the large power dusting machine including the
brushing and feeding device. In operation, it hangs from
the shoulders of the user directly in front of him and ob-
tains its power from a fan which is rotated by a hand crank

operating a gear set.

 

This improved type of hand operated duster
has made possible the general use of the dusting method
by many small growers and planters who heretofore have
considered the muss and fuss of liquid spraying as being

too much trouble and too complicated for small properties.

-26—
Ameteur gardeners, owners of homes having
ornamental plants and shrubbery about the grounds, etc.,
were also turning to the dusting method as an easy and
efficient means of ridding their places of "bugs" and di-
seases. It was considered that the blower gun was too
large and too expensive for this type of dusting work so a
small hand dust outfit was developed which had no fan but
which consisted of an air chamber and plunger, which, when
pushed backward and forward by the operator, created an
air pressure sufficient to throw a tiny cloud of dust from

the small hopper of the machine.

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On account of the ravages of shade tree

pests invardous parts of the country, particularly in

New England, and the almost numberless difficulties en-

countered in fighting these pests by liquid sprays, it
~27<
seemed wise to attempt to develop a proper duster for this
work. Conseouently, a huge duster operated by an eight
horse power gasoline motor was designed. All of the
principles used were the same as with the standard or-
chard machines except for the size and capacity of the
various parts. Extensive field experiments were carried
on in the Buffalo, N. Y.,Parks with one of these outfits
and surprisingly effective results were secured the first
season against Tussock Moth, with a mixture of 80% Lime
and 207 Arsenate of Lead. The highest elm trees were
readily reached and thoroughly covered with the dust and
treatments were possible in thickets and heavily wooded

second growth sections which heretofore were impractical

to spray.

ee

 

 
The improvement of dusting machines and
materials for using dry insecticides and fungicides with
air as a carrier instead of water, was accomplished by a
series of successive steps beginning first with a scientific
analysis of the actual field requirements of such machines
and materials and slowly perfected by closely collaborating
practical field experiments, technical laboratory experiments
and factory practice in the manufacture of the products. The
usual process being:

. First: Extensive field and laboratory
tests to determine the practicability of proposed machines
or materials.

Second: If these experiments were success-
ful, factory tests were begun to determine the feasibility
of manufacturing such machines or materials for commercial
purposes.

Third: If these factory experiments were
successful, the finished manufactured product was again
proved by field and laboratory experiments before the ma-
chines and materials were turned over to orchardists for
commercial use.

When the improvement of dusting machines >
and materials was undertaken by the writer and assoc-
lates in 1915, there were, as far as could be learn,
ed, less than one hundred fifty dusting machines of
all types in commeroial use for orchard fruits. On
January 1st, 1920, there were as far as could be learned,
about five thousand of these improved machines in the

hands of commercial orchardists in the United States

and Canada. Practically every Experiment Station
=29e
in the fruit growing states was working with dust in

one way or another and the United States Department of
Agriculture had underway about twenty-five distinct ex-
pefiments in various parts of the country. Greater
improvements in both machines and materials than have
already been accomplished will unquestionably come and
with the impetus already given to this method of treat-
ment, it is certain that during the next few years,
dusting, by virtue of its many peculiarly advantageous
features, Will practically replace liquid spraying as a
means of protecting commercial orchards agains the depreda-

tions of injurious insects and diseases.
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