FUMIGATION
METHODS

A Practical Treatise for Farmers, Fruit
Growers, Nurserymen, Gardeners,
Florists, Millers, Grain Dealers, Trans-
portation Companies, College and
Experiment Station Workers, etc.

By WILLIS G. JOHNSON

Formerly Professor of Entomology and Invertebrate Zoology at the
Maryland Agricultural College and Stale Entomologist; author of
many special reports on economic topics; associate editor A merican
Agriculturist weeklies ; Fellow in the American Association for the
Advancement of Science; Member of the Association of Economic
Entomologists, the A merican Pomological Society, the Society for
the Promotion of Agricultural Science, etc. : : : : : : : : :

ILLUSTRATED

NEW YORK

ORANGE JUDD COMPANY

1902

COPYRIGHT, 1902
BY ORANGE JUDD COMPANY

TABLE OF CONTENTS

CHAPTER I

PAGE

ECONOMIC USE OF HYDROCYANIC ACID GAS . . 1-8

Early history — First use as an insecticide —
Experiments in California — Dry gas process
— Inauguration of night fumigation — First use
in Eastern orchards.

CHAPTER II
How THE GAS is MADE 9-11

Chemical ingredients — Combination of chem-
icals — Action of chemicals — Vessel used for
generation — Character of residue formed.

CHAPTER III
PHYSIOLOGICAL EFFECTS ON PLANTS .... 12-24

Experiments by Woods and Dorsett — Practi-
cal tests upon orchard trees and nursery stock
— Effects on seeds and low-growing plants.

CHAPTER IV

EFFECTS ON ANIMAL LIFE 25-26

Fortunate accident — Chickens pick up cyanide
shaken from a bag — Cat destroyed in green-
house while asleep — Experiences with various
animals.

CHAPTER V
APPARATUS FOR USE IN ORCHARDS .... 27-34

Early types for fumigators — Construction of
sheet tents — Oiling and painting tents — Vege-
table decoction for treating tents.

CHAPTER VI

BELL AND HOOP TENTS 35~47

General description — Method of handling —
The hoop tent popular in California — Construc-
tion and manipulation.

iii

iv FUMIGATION METHODS

PAGB
CHAPTER VII

CONSTRUCTION AND MANAGEMENT OF SHEET TENTS . 48-58

Methods of making and handling sheet tents
— Apparatus used in Eastern orchards — De-
scription of California outfit.

CHAPTER VIII
EMORY FUMIGATOR WITH MODIFICATIONS . . , 59-75

Development of the Emory fumigator — Gen-
eral description — Apparatus for handling — Cost
of construction — The Miller type — Method of
operating — The New York box fumigator.

CHAPTER IX
ESTIMATING GAS FOR ORCHARD WORK . . . 76-83

Amount of chemicals — Cyanide necessary —
Destroying black scale on citrus trees — Red,
brown, and purple scale — Orchards on damp
grounds — Eastern orchards — Comparative
value of cyanide.

CHAPTER X

DAYLIGHT FUMIGATION AND COST OF APPLICATION . 84-92

Experiences in Eastern orchards — Expert
opinion from California — Time of application —
— Cost of orchard fumigation — Location of or-
chard considered.

CHAPTER XI

EQUIPMENT FOR FUMIGATING NURSERY STOCK . 93-111

Conditions considered — Construction and use
of boxes — How to build a fumigatorium — Vari-
ous types described.

CHAPTER XII
CONSTRUCTION OF VENTILATORS AND FLOORS . 112-117

Form used in Canada — Arrangement em-
ployed in Ohio — Method in Delaware — A
Western idea.

CHAPTER XIII
PRACTICAL HINTS TO NURSERYMEN . . . 118-125

Estimating chemicals — Low-grade stock — Cost
of nursery stock fumigation — Value of small
room — Preparation of trees — Materials needed
— Cellars and cars — Use of canvas over wagon
— Points to remember.

OF CONTENTS V

CHAPTER XIV

GREENHOUSE AND COLD FRAME FUMIGATION . 126-146

Effects on foliage — Preparation of the house
— How to prepare the jar — Boxes for fumigat-
ing small plants — Experiences with various
plants — Experiments in greenhouses — Estimat-
ing cubic contents — Cold frames — General sum-
mary— Practical application.

CHAPTER XV

SMALL FRUITS AND PLANTS 147-152

Amount of chemicals for strawberry plants —
Experimental and practical tests — Application
on melon, cucumber, cabbage, etc. — Difficulty
of fumigating in rows.

CHAPTER XVI

APPLICATIONS IN MILLS, ELEVATORS, AND OTHER

ENCLOSURES 153-176

First use in mills — Necessary preparations —
Resisting power of insects — Estimating chemi-
cals— Application — Cars and ships — Dwelling-
houses and storerooms — Explosive properties —
Practical application — Mills and elevators —
Tobacco warehouse — Houses and Laboratories.

CHAPTER XVII

GRAINS AND OTHER SEEDS 177-185

Experimental tests — Influence upon seed
germination — Fumigated grain fed to mice —
Effects on dry and damp seeds — General sum-
mary of results.

CHAPTER XVIII

DIFFUSION OF HYDROCYANIC ACID VAPOR . . 186-197

General experiments — Effect of moisture on
foliage — Absorbent effect of fresh earth — Dif-
fusion in large room — Rapid loss of vapor —
General results considered.

vi

FUMIGATION METHODS
CHAPTER XIX

RECENT WORK WITH HYDROCYANIC ACID GAS . 198-220

Successful application in England — Vineries
and Conservatories — Use on ordinary green-
house pests — Use in New South Wales — Cost of
material for tents — Orchard work in Cape
Colony — Experiments at New York Agricul-
tural Experiment Station — Fumigation of or-
chard trees.

CHAPTER XX
ECONOMIC VALUE OF FUMIGATION . . . 221-256

First use upon nursery stock — Fumigating
greenhouses — Olive trees fumigated — Fumiga-
tion understood and appreciated — The superi-
ority of fumigation — Operations in Canada —
Form of fumigating box — Common-sense views.

CHAPTER XXI

FUMIGATION WITH CARBON BISULPHID . . 257-284

First use to destroy insects^Chemical proper-
ties— Commercial uses — Instruments for appli-
cation— Fumigating mills and other buildings —
Practical work — Precautions — Effects upon
seeds — Fruits and plants — Destroying pests in
woolens, furs and clothes — Killing prairie-dogs,
gophers, squirrels, etc. — Expert opinions of its
practical value — Exterminating rats and mice —
How it is put up.

CHAPTER XXII

LAWS REGULATING NURSERY AND ORCHARD INSPEC-
TION AND FUMIGATION 285-302

General review of the situation in the United
States — Abstracts of State Laws.

CHAPTER XXIII

FOREIGN LAWS REGULATING SHIPMENTS OF FRUITS
AND NURSERY STOCK . . . .

Abstracts of the Foreign Regulations — List
of ports of entry.

303-309

ILLUSTRATIONS

PAGE

Portrait of the Author .... Frontispiece
York Imperial Apple Tree, Fumigated with Six Times

Normal Dose ........ 17

Ogon Plum, Fumigated with Three Times Normal Dose 18

Ogon Plum Tree, .Fumigated ...... 19

Peach Tree, Fumigated with Normal Dose ... 21
Effects of Gas on Mature Peach Trees, where Overdoses

were Used ......... 23

The Wolfskill Fumigator 29

The Titus Fumigator ........ 30

The Culver Fumigator ....... 31

Culver Tent and Morse Fumigator ..... 32

Canvas Tent with Square Top and Base .... 33

The Preble Fumigator, as Used in California Orchards . 36

Raising Small Hoop Tent ....... 37

Hoop Tent Almost in Position 38

Small Hoop Tent Ready for Chemicals . . . . 39

Lifting Large Hoop Tent from Ground .... 40

Adjusting Large Hoop Tent 41

Lifting Tent After Fumigation . . . • . . .43

Covering Tree with Large Hoop Tent .... 44

Method of Shifting Large Hoop Tent. (After Woodworth) 45

Orchard Work with Sheet Tents in the East ... 47
Manipulating Sheet Tents with a Single Pole. (After

Woodworth) ......... 48

Handling a Tent with a Single Pole 49

Removing Sheet Tent by Means of Pole and Helpers . 50

Covering Large Orange Trees with a Sheet Tent . . 51
Sheet Tent in Position Over an Orange Tree Ready for

Chemicals ......... 53

vii

viii FUMIGATION METHODS

PACK

^Removing Sheet Tent, Assisted by a Horse ... 55

Fumigating Apparatus Readyjor Transportation . . 56

Tenting an Orange Tree in California .... 57

Tent in Position about Ready for Chemicals ... 58
Model Type of Emory Fumigator with Hood Fully

Extended ......... 60

Practical Work with the Emory Fumigator . . . 61

Folding Paper Fumigator compared with Sheet Tent . 62

Apparatus for Manipulating the Emory Fumigator . 63

Fumigating an Orchard on a Mountain Side ... 65
Practical Application of the Emory Fumigator on Rough

Land 67

Placing Fumigator Over Tree, Showing also Tray for

Chemicals 68

Fumigator Nearly in Position ...... 69

Placing the Chemicals Under Fumigator .... 70

Airing the Fumigator Just Before Removal ... 40

Transferring the Fumigator ...... 73

Fumigator Designed at the New York Experiment

Station 74

Japanese Plum Tree, Fumigated in October ... 85

Charging a California Hoop Tent ..... 89

Wagon for Carrying Chemicals in Orchard ... 91

Box Used by a Nurseryman in the South. (After Sherman) 94
Type of Box Used by a Canadian Nurseryman. (After

Lochhead) ......... 95

The Open Box Used in Some Maryland Nurseries.

(Original) ......... 96

Open Box Reversed Ready for Chemicals. (Original) . 97

Large and Convenient Fumigatorium .... 98

Room Where Trees are Fumigated by the Wagon Load . 99

Double Rooms Built in End of Packing-shed . . . 100

Single Room Used in Winter for Grafting . . . 101
Neatly Constructed Single Room with Corrugated Iron

Roof 102

Handy and Cheap House for Small Nursery . . . 103

Outline of Model Fumigating House. (Original) . . 104

Plan for Slat Floor. (Original) 104

ILLUSTRATIONS ix

PAGE

General Plan of Floor. (Original) ..... 105

Where Trees are Fumigated by the Million . . . 106

Well-built Single-room House for Small Nursery . . 106

Complete Fumigating House in Utah .... 107

Sectional View of a Model Utah House. (After Moore) . 108
Double House in Canada for Fumigating Trees on a

Wagon 109

Fumigating House at the Ontario Agricultural College . no
Methods of Ventilating a Fumigating House. (After

Lochhead) ......... 112

Diagram of Generator and Sectional View of Fumiga-

torium. (After Webster) 113

Lower Portion of Fumigatorium. (After Sanderson) . 114

Generator and Details for Handling. (After Sanderson) 115

Method of Fumigating Greenhouse ..... 129

Box for Fumigating Small Plants and Cuttings . . 131
Diagram for Determining Cubic Contents of Greenhouse.

(After Galloway) ........ 140

Even and Three-quarter Space Houses. (After Woods

and Dorsett) ......... 142

Interior Arrangement for Fumigating Buildings. (Orig-
inal) . ( . . . 164

Fumigating in a New South Wales Orchard . . . 204

Two Orange Trees, Fumigated and not Fumigated. . 205
Average Specimen of Orchard Fruit from a Fumigated

Tree 207

Average Specimen of Orchard Fruit from a Tree not

Fumigated ......... 207

Improved Method of Fastening Door on the Lowe Fumi-

gator 215

The Sirrine Type of Folding Fumigator .... 217

Canvas Tent with Felt Type of Pyramidal Hood . . 219

Fumigated Citrus Orchard in California .... 222

Sprayed Orange Tree in a California Orchard . . . 223

PUBLISHER'S PREFACE

T was the original plan of the author to have
used as a frontispiece in this work a portrait
of Mr. D. W. Coquillett, who discovered the
economic value of hydrocyanic acid gas as an
insecticide. Mr. Coquillett prefers to be remembered
by the discovery he made in his experimental and prac-
tical work with hydrocyanic acid gas. The publishers
therefore take pleasure in introducing this volume
with a portrait of the author, who has done so much
to utilize in a practical way the discovery made by Mr.

Coquillett.

ORANGE JUDD COMPANY.

AUTHOR'S PREFACE

CE radical changes in conditions during the
past eight or ten years along agricultural and
commercial lines have been followed by the
general distribution of many insect pests of a
serious character. In commercial transactions the dan-
gers have been so great along certain lines that many
State laws have been enacted to prohibit the distribu-
tion of such insects as the San Jose scale and others of
a dangerous nature. Some foreign governments have
enacted such legislation as to make it practically im-
possible to ship fruit and nursery stock without the
most rigid inspection and fumigation before entry is
permitted.

Ability to successfully combat noxious insects is a
problem of the most vital importance to farmers, fruit
growers, nurserymen, gardeners, florists, millers, grain
dealers, transportation companies, merchants, grocers,
housekeepers and others. This is especially true of
the fruit, nursery, and grain industries. The use of
hydrocyanic acid gas and carbon bisulphid, two very
powerful insecticides, have largely solved these serious
problems. We owe the discovery of carbon bisulphid
as an insecticide to M. Doyere, while that of hydrocyanic
acid gas belongs to D. W. Coquillett. Their practical
application has been one of gradual development.

With the advent of the San Jose scale in Eastern

XIV FUMIGATION METHODS

nurseries and orchards the demand for exact informa-
tion about a cheap and reliable remedy became a live
topic. Little or nothing had been done with hydro-
cyanic acid gas fumigation outside of California.
From what the writer had observed in California, he
was certain that this method wras the most promising
and would meet the conditions in the Hast and other
places if properly adapted. Hundreds of experiments
and practical applications were made by the writer to
test the gas in orchards, nurseries, greenhouses, mills,
warehouses, granaries, and various other places. The
outcome of these tests proved conclusively that hydro-
cyanic acid gas was a cheap and reliable remedy for a
very large range of insects usually found in such places.

In the present volume the writer has attempted to
embody the practical results of his own experiences as
well as those of others who have used these gases suc-
cessfully. In his endeavors to gather together the
fragmentary notes, scattered as they were in litera-
ture throughout the world, the author feels that this
work is not complete and perfect in every respect. It
embraces, however, for the first time in one volume,
a general survey of this important and timely subject.

Where the writer has not given personal credit in
the text he wishes to extend the same courteous
acknowledgment to all who have in any way con-
tributed to the contents of this volume. Hspecial
thanks are due to Mr. D. W. Coquillett for reading
and correcting proofs, and to Mr. Herbert Myrick,
Editor and Proprietor of the Orange Judd weeklies and
books, through whose aid and courtesy this volume is
written and published.

AUTHOR'S PREFACE xv

All the illustrations reproduced herewith are from
photographs taken by the author, excepting those
acknowledged below or credited in the text. To the
following the author desires to express his thanks : to
the Secretary of the California State Board of Horti-
culture, for photographs and drawings from which
Figs. 8 to ii inclusive, 13, 30 and 31 were reproduced;
to the Director of the California Experiment Station,
for permission to use electrotypes of Figs. 14 to 21 in-
clusive, 23, 45, and 46 ; to Mr. R. P. Cundiff, Horti-
cultural Commissioner Riverside District, California,
for photographs of Figs. 26, 27, 28, and 29 ; to the
Director of the New York Agricultural Experiment
Station, for permission to use photographs of Figs. 43,
79, and 80 ; to the Secretary of the Pennsylvania State
Board of Agriculture, for loan of electrotypes of
author's photographs; to Mr. D. M. Moore, of Utah,
for photograph from which Fig. 62 was made; to Prof.
William Lochhead, of the Ontario Agricultural Col-
lege, for photographs of Figs. 64 and 65 ; to Mr. W.
J. Allen, of New South Wales, for use of Figs. 75, 76,
77, and 78 ; to Dr. E. P. Felt, State Entomologist of
New York, for photograph of Fig. 81, and finally to
Mr. C. M. Heintz, editor of the Rural Calif ornian,
for photographs from which Figs. 82 and 83 were
reproduced.

Although the author has taken unusual pains to
make this work technically correct yet popular in
style, there have, no doubt, crept in some mistakes.
When readers note any error, typographically or oth-
erwise, they will confer a great favor on the writer by
reporting same, so corrections can be made in future

XVI FUMIGATION METHODS

editions. If this volume will in any way answer the
numerous questions asked on the subject of fumiga-
tion, either with hydrocyanic acid gas or carbon bisul-
phid, or suggest methods for future work along
these lines, the writer will feel repaid for his labors.

Wnjjs G. JOHNSON.

NEW YORK CITY,

February 75, igos.

FUMIGATION METHODS

CHAPTER I
ECONOMIC USE OF HYDROCYANIC ACID GAS

T"HHK discovery of the value of hydrocyanic acid
gas as an insecticide was due to the presence
of the cottony cushion scale in the citrous
orchards of California. This insect was un-
wittingly introduced into California from Australia.
For a time it seemed certain that the pest would ruin
the orange and lemon industry in spite of the con-
certed efforts of the most intelligent horticulturists to
combat it. Despairingly, the growers appealed, as a
last resort, to the United States Department of Agri-
culture for aid. The matter was taken up by the
Division of Entomology, and two assistants were
detailed by Dr. C. V. Riley, then Entomologist, to
undertake the study of methods for the control of the
insect. These assistants were D. W. Coquillett and
A. Koebele. To Mr. Coquillett belongs the credit of
first discovering the value of hydrocyanic acid gas,
now so extensively used, for the destruction of insects
and other animal pests.

In addition to the detailed account of the gas treat-
ment given by Mr. Coquillett, in the report of the

2 FUMIGATION METHODS

Department of Agriculture for 1887, and in "Insect
Life," Vol. III., by way $>f explanation, he wrote me
March 21, 1898, as follows : " During the summer of
1886 I was employed by the United States Depart-
ment of Agriculture to carry on a series of experiments
at lyos Angeles, California, against the cottony cushion
scale {Icerya purchast), but owing to an insufficient
appropriation I was laid off on August ist of that
year. As no perfect remedy had at that date been
discovered, I determined to experiment with gases
in a private capacity and at my own expense.
Accordingly, during the first wfeek of the following
month I began experimenting with hydrocyanic acid
gas, which I thought would be the best for the pur-
pose, owing to its very poisonous qualities, the rapidity
of its generation, and the readiness with which it dif-
fuses itself in the air. Nobody suggested to me to
try this gas. It was not until the following July that
the Department of Agriculture again placed me on its
rolls."

It will thus be seen that Mr. Coquillett continued
to work on the problem of destroying the scale, though
at his own expense, and in September, 1886, began
seriously to study the methods of fumigation. Fumi-
gation with carbon bisulphide had been inaugurated
on a small scale by J. W. Wolf skill and his very able
foreman, Alexander Craw, at L,os Angeles. At their
place Mr. Coquillett began his experiments, profiting
by the facilities here provided. It was here he first
conceived the idea of using hydrocyanic acid gas.
About six months were required to perfect methods.

The result of the work in the Wolf skill orchards

ECONOMIC USE OF HYDROCYANIC ACID GAS 3

was watched with keen interest by those whose trees
were fast being ruined by the scales. Many growers
became impatient to know the remedy so carefully
guarded by the experimenters. Finally, a number of
horticulturists about San Gabriel asked Prof. E. W.
Hilgard, of the University of California, for a chemist
to experiment in their orchards with various gases.
F. W. Morse was detailed for this work, and found,
like Mr. Coquillett, that hydrocyanic acid gas was by
far the most satisfactory. In the course of these ex-
periments certain parties who had witnessed the former
experiments recognized the odor of gas, and thus the
secret, so zealously guarded, was given to the public.
Although discovered and used by Mr. Coquillett and
his associates six months previous to the announce-
ment of Mr. Morse, the first general information about
the gas as an insecticide was given to the public by
the latter gentleman in a Bulletin (No. 71) from the
University of California Experiment Station.

Extensive experiments were continued by Mr.
Coquillett. In July, 1887, he was again made an
assistant of the Department of Agriculture, and did
more than any other person to develop and perfect the
present methods of fumigation. The main difficulty
encountered in these early experiments was the inju-
rious effect the gas had upon the foliage. The injury
was lessened greatly by the ' ' soda process ' ' of Morse,
which consisted in adding ordinary baking soda to the
cyanide solution, using something like two and a half
times as much soda as there was cyanide in the solu-
tion, the result being the production of carbonic acid
gas, thus diluting the hydrocyanic acid gas.

4 FUMIGATION METHODS

Speaking of the early experiences with this gas,
Prof. C. W. Woodwork says that previous to the
time of the publication of Morse's soda method, Mr.
Coquillett accomplished a similar diminution of injury
by slow generation of the gas. This Mr. Coquillett
accomplished by means of a generator consisting of two
parts: from one the sulphuric acid passed in a fine
stream, regulated by a stop-cock, into the other con-
taining dry cyanide. These facts were clearly set forth
by Alexander Craw in a paper before a meeting of
fruit growers at I,os Angeles, in October, 1887.

The ' ' dry gas process ' ' was soon devised by Mr.
Coquillett. It consisted in passing the gas from the
generator through sulphuric acid, allowing it to come
in contact with the foliage. In this he used a solution
of cyanide. This was the situation at the time of the
publication of Mr. Coquillett 's first paper, cited above,
wherein these three processes were described quite
fully. He strongly recommended his last process as
the cheapest and most convenient; and Mr. Morse, in
a later paper, practically abandoned his soda method in
favor of the dry gas process.

Injury to trees from the first has been a specula-
tion and controversy, and even now it must be con-
fessed that we are far from possessing sufficient data to
enable us to solve any considerable part of the problem.
The results have been very uncertain, proving that
there are a number of factors involved. One of the
earliest explanations suggested was that faulty dis-
tribution of the gas would tend to cause burning
wherever the pure or slightly diluted gas came in con-
tact with the leaves. Practical experience bore out

ECONOMIC USE OF HYDROCYANIC ACID GAS 5

this idea, so that in most of the earlier work elaborate
provision was made for the mixing of the gas and the
air contained in the tent. Generally some form of
blower connected with the generator was used. How-
ever, later work has demonstrated that this is of minor
importance.

The first theory of Mr. Coquillett was that the
mixing, or perhaps the combination, of the gas with
water rendered it more injurious. Both of his proc-
esses were based on this idea. He explained the
effectiveness of the soda process as arising from the
affinity of the carbonic acid for water. Mr. Morse's
original ideas are not made plain in his writings, but
his later studies led him to believe that the develop-
ment of ammonia in the gas was the most important
cause of injury. The injurious effects of ammonia
are well known, and he demonstrated the presence
of ammonia in the gas, especially in that generated
from a solution of cyanide. Thus there were two
theories accounting for the good effects of the methods
then known, and both agreed in favoring the dry gas
process. The latter theory seems to have had more
foundation in fact, but it soon became evident that
there were other still more important factors determin-
ing the injury to the foliage.

The successful introduction of ladybirds from Aus-
tralia into California, and the promising results of the
importation, caused the gas method to remain at a
standstill for some time. The interest in fumigation
was later revived, however, on account of the red
scale {Aspidiotus aurantii}, which was becoming quite
troublesome in many orchards in Orange County. By

6 FUMIGATION METHODS

invitation, Mr. Coquillett took his apparatus to the
orchards of A. D. Bishop, and commenced a new series
of tests. The ones giving the best results were the
same as some of Mr. Coquillett's earliest experiments,
in which the gas was generated in a simple generator
beneath the tent, according to the formula now gen-
erally used.

It was generally believed by Mr. Coquillett at this
time that it was the aclinic rays rather than the heat
rays of the sun that injured the foliage. It had been
previously noticed that trees were more injured during
the middle of the day than at other times, and it
was usually attributed to the heat. Working on his
theory, Mr. Coquillett began experiments with a
black tent, and confirmed his belief that it was the
aclinic and not the heat rays that caused the trouble.
Naturally, night work in fumigation soon followed.
It was on Mr. Bishop's place where the first practical
night fumigation was inaugurated. The success of
these experiments has been far-reaching. The adop-
tion of methods here perfected has been quite univer-
sal. In practical results, the fumigation at night is
satisfactory and regarded as essential to good fumiga-
tion in citrous orchards. Mr. Bishop, in company
with some neighbors, applied for a patent on the proc-
ess, which was granted, even in the face of a strong
protest from Mr. Coquillett and Dr. Riley to the Com-
missioner of Patents. L/ater, however, the courts de-
cided that the process was not patentable, and the
controversy ended.

The main interests centering around fumigation
were confined mainly to California until 1893. ^n

ECONOMIC USK OF HYDROCYANIC ACID GAS 7

August of that year the San Jose scale (Aspidiotus per-
niciosus Comstock) was found at Charlottesville, Va.,
on the grounds of Dr. C. H. Hedges. This was the
first discovery of this pest east of the Rocky Moun-
tains, and naturally caused a good deal of apprehen-
sion on the part of fruit growers all over the country.
Again Mr. Coquillett was detailed by the United States
Department of Agriculture to conduct experiments
with hydrocyanic acid gas on these infested trees. The
work was begun and completed in March, 1894.

The gas process was not, however, generally
recommended for the fumigation of deciduous trees.
From the experiences of growers in California I felt
certain that the gas could be applied equally as suc-
cessful to deciduous fruit trees in the Bast and else-
where, if properly handled. With practically nothing
as a guide, except the general work done in California,
and little or no encouragement from leading Eastern
entomologists, I began a series of experiments, in the
spring of 1897, upon young plum, pear, apple, and
nectarine trees. The results of these preliminary ex-
periments were so very satisfactory that I was prompted
to continue my work on bearing trees in the fall of
1897. With the aid of Robert S. Emory, of Chester-
town, Md., a successful fruit grower, we perfected an
outfit and completed the first successful fumigation of
a large orchard in the East. The results of this work
were watched with much interest in this and other
countries. While the methods of generating the gas
have not been materially changed, the amounts of
chemicals have been adapted to suit conditions. The
apparatus for containing the gas has bee"n improved,

8 FUMIGATION METHODS

and the box system, designated by me as the " Kmory
Fumigator," has been perfected, and is now commonly
used by orchardists and others.

Since 1894 the gas nas also been used in green-
houses for the destruction of certain pests. The
demand for fumigated trees led me to conduct an
extensive series of experiments with the gas upon
nursery stock of various kinds and grades. These
tests, begun the fall of 1896 and completed the spring
of 1899, have shown conclusively the maximum and
minimum amount of gas young trees will withstand
without injury. Many obscure points about the con-
struction and management of fumigating houses have
been made clear.

In 1898 I first suggested the use of hydrocyanic
acid gas as a remedy for the destruction of insects in
mills, elevators, and warehouses. The system has
since been perfected under my direction, and it is now
in general use in this and other countries. In 1900 I
demonstrated that the gas could be used in tight
buildings with perfect success and .safety, even in the
thickly populated districts of a city, wThen properly
handled, for the destruction of certain pests, including
rats and mice. The fumigation of street-cars and
railroad coaches to destroy bedbugs and other vermin
is commonly practiced in many places. The gas is
also employed to rid houses of undesirable pests, but
in such cases should be handled with great care.

CHAPTER II
HOW THE GAS IS MADE

T|HK chemicals used for generating hydrocyanic
acid gas are ( i ) fused cyanide of potassium
(KCN), (2) sulphuric acid (H2SO4), and
(3) water (H2O). The cyanide should be
guaranteed 98-99 per cent. , which is practically chem-
ically pure. There is upon the market in some places
an old brand of cyanide of about 58—60 per cent,
purity. This should be avoided.

The best grade of commercial sulphuric acid, with
a specific gravity of at least 1.83, should be used. A
grade known as chamber acid used ordinarily in the
manufacture of fertilizers will not do, and under no
circumstances should it be employed. Water from any
source will sufiice, the only requisite being that it
should be clean.

In combining the chemicals (i), measure the acid in
the glass beaker marked ounces on the side, and pour
it in an earthenware crock, wooden bucket, tub, or
pickle jar; (2), measure the water in the same beaker
and pour it on the acid; (3), drop in the cyanide, bag
and all, if wrapped in paper, close the door or drop the
tent quickly, and leave desired length of time.

Action of the chemicals. — When the water is poured
into the jar upon the acid, a slight evolution of steam
arises, which is not dangerous. As soon as the cyanide
is dropped in the acid and water there is a bubbling

9

10 FUMIGATION METHODS

and sizzling similar to that produced by a piece of red-
hot iron in cold water. Xhere is also a dense cloud of
so-called steam given off. This bubbling is due to the
action of the acid on the cyanide, and the so-called
steam is the gas being produced. The result of this
chemical action is the production of hydrocyanic acid
gas (HCN), known in the liquid form as prussic acid,
according to the following equation : 2KCN + H2SO4
= 2 HCN H- K2SO4. The gas has an odor somewhat
similar to that of peach pits, but do not stick your
nose over a vessel in a house or under a tent to test it.
These fumes, if inhaled, would prove fatal, and thus
the necessity of great care.

The vessel. — Various kinds of vessels can be used
for the acid and water. Usually an ordinary earthen
jar, china dish, or bowl is used. In some cases a
wooden pail or tub can be used to good advantage.
As a rule, earthenware vessels are employed in orchard
and nursery fumigation. The size of the vessel will
depend upon the amount of material to be used for
generating the gas. Sometimes in mills, warehouses,
elevators, and other enclosures large jars or wooden
pails containing from two to three gallons are necessary.
Under no circumstances should tin or iron vessels of
any kind be used, as the acid would quickly corrode
and ruin them. For small boxes a china bowl or tea-
cup can be used.

Residue in the jar. — After a charge of gas has been
liberated there will be a residue left in the jar. At
first, and while still warm, it is a whitish liquid, with
a bluish cast, but as it cools it becomes thick like paste

HOW THE GAS IS MADE II

and crystalizes when cold. It is easily soluble in
water. Immediately after the room, tent, or other
inclosure has been ventilated the desired length of time
the contents of the jar should be emptied on a manure
pile, in a hole prepared especially for that purpose, or
under the tree close to the trunk. As the acid and
potash left behind are both excellent fertilizers they
should be saved by composting them either with
manure or dirt. The residue consists of sulphate of
potash, sulphuric acid, and water. The sulphuric acid
will unite with lime in the soil, forming gypsum.
Never pour the residue in an exposed place, where a
person would be liable to step in it, or where a tent
can be dragged through it.

No dangerous deposit formed. — The question is
often asked about the possibility of hydrocyanic acid
gas forming a deposit upon any of the substances with
which it might be brought in contact in its ordinary
use as a fumigant, either in greenhouses or in buildings
infested by indoor insects. Dr. H. W. Wiley, chemist
of the United States Department of Agriculture,
states that there is no possibility whatever of such a
contingency, unless the gas comes in contact with some
alkaline body, such as soda or potash, with which it
would form a salt. The soluble cyanides are extremely
poisonous, and if this gas were to act upon lye, or any
similar alkaline body, a certain amount of cyanide
would be produced. In a dry room, in the absence of
alkaline bodies, there could not be any possible danger of a
poisonous body being formed.

CHAPTER III
PHYSIOLOGICAL EFFECTS ON PLANTS

s NOTED in a previous chapter, early experi-
menters had observed the burning effects of
the gas upon foliage when used under certain
conditions and overcome the difficulty by
night fumigation. It remained for Dr. Albert F. Woods,
now Chief of the Division of Vegetable Physiology and
Pathology, United States Department of Agriculture,
and an assistant, P. H. Dorsett, to solve this problem
in connection with certain greenhouse plants. In 1 894
they began a series of experiments, and proved con-
clusively that plants are less injured by a short ex-
posure to a relatively large amount of gas than by a
long exposure to a relatively small amount, and also
that a stronger dose a short time was more destructive
to the insects affecting the plant. They further de-
monstrated the physiological effect of the gas upon
the plants by subsequent experiments. They summed
up the resisting power of the plant as dependent largely
upon the open and closed condition of the breathing
pores of the leaf, the peculiarities of the cell contents,
and the temperature of the inclosure.

I found the same variations in the field, where we
used the gas largely in the control of San Jose scale
and other insects. The first problem taken up in this
connection was the physiological effect of the gas
upon deciduous trees in the East. The conditions in

12

PHYSIOLOGICAL EFFECTS ON PLANTS 13

Eastern orchards were quite different from those in
California. With our experiments we did not begin
with the deciduous trees until the function of the foli-
age had been performed, namely, late in the fall, just
previous to the heavy frost. These experiments were
conducted in late September and early October. It
made little or no difference to us whether we scorched
or burned the leaves; our main point was to determine
what effect the treatment was going to have upon the
fruit or leaf development for the following season.

The next practical application of the gas was its
use for the fumigation of nursery stock. As no pre-
cise experiments had been conducted in the Hast, the
writer began a series in March, 1897, upon young
apple, peach, nectarine, plum, and pear trees. They
varied in hight from four to five feet, were thoroughly
dormant, and badly infested with the San Jose scale.
They were placed in a room 4x7x7^ feet, prepared
for the purpose. A general, miscellaneous lot were
exposed thirty minutes in gas generated from 0.20
gramme of cyanide of potassium per cubic foot of air-
space inclosed. Another lot was exposed to gas from
0.20 gramme up, through the series formed by adding
0.05 gramme each time, until 0.50 gramme was
reached. All the trees of these lots were observed
very closely for two years. No injury was noticed,
and not a living scale was ever detected upon them.
The cyanide used in these experiments was the 98-99
per cent, pure, while that used at first in the California
orchards was the old 58 per cent. ; this must be taken
into account when considering the effects of the gas
on trees and amounts of chemicals used.

14 FUMIGATION METHODS

Orchard experiments. — In the fall of 1897 I began,
perhaps, the largest serie^ of experiments ever under-
taken in the East for the destruction of San Jose scale.
The orchard chosen was a nine-year-old Bartlett dwarf-
pear in full foliage. Canvas tents were used. The
trees were fumigated at all hours of the day and under
varying conditions of weather. We had sunshine,
cloudy and foggy days, rain, sleet and snow, windy
and calm weather. In one series, September 29th, with
a temperature of 70° F. , we used 0.40 gramme cya-
nide per cubic foot instead of 0.20, as in most of our
experiments. The leaves on all the trees were very
brown, in fact, almost black. Within five minutes
after the tents were removed the petioles were black
almost to the base ; the leaves fell a few days later.
The following spring the leaves came out as normally
as on any other trees in the orchard where no fumiga-
tion occurred. There was about one-quarter as much
fruit on these trees, however, as upon those that had
been fumigated with the normal strength, that is, 0.20
gramme. Other trees were treated at night with the
same double dose, at a temperature of 58° F. The
foliage, the first week, showed no injurious effect
whatever, and remained just as green as on trees not
fumigated. The eighth day, however, the leaves be-
gan dropping, and a few days later were all off. The
leaf buds came out the following spring, but the fruit
was only about half as abundant as on surrounding
trees. The double dose, it would therefore seem, is
injurious at least to the fruit buds of Bartlett pear
under such conditions.

The final outcome of the whole series of experi-

PHYSIOLOGIC AI, EFFECTS ON PLANTS 15

ments showed that gas was most injurious to foliage
on sunshiny days late in the fall between 9 A.M. and
4 P.M. ; that the dormant leaf and fruit buds treated
with o. 20 gramme cyanide per cubic foot were not in-
jured ; that burned leaves, that is, those injured by
the gas, fall readily ; that trees treated in the morning
before 9 o'clock and in the afternoon after 4 o'clock,
even in sunshine, have the leaves little affected ; that
trees treated at night with normal doses do not have
the foliage hurt at all.

On March 18, 1898, experiments were begun upon
plum trees, using the same standard dose, just as the
buds were unfolding, and observed no injurious effects
whatever. June 3, 1898, eight young plum trees,
from 8 to 10 feet in hight, were fumigated with o. 16
gramme cyanide. The exposure varied from 5 to 12^
minutes, in the sun at 80° F.; in every instance all
the lice were killed and the foliage not injured. July
8, 1898, three cherry trees were fumigated with o. 16
gramme cyanide from 5 to 10 minutes. The trees
were infested with the cherry slug. A five-minute
exposure did not injure the foliage at all, but did not
destroy over 60 per cent, of the slugs; on the other
hand, 7^ to 10 minutes destroyed all the slugs, but
.severely hurt the leaves. June 13, 1898, two pear
trees, badly blighted, were fumigated with 0.20
gramme cyanide per cubic foot, for 6 and 10 minutes
respectively. We could see no bad effects on the
leaves and no decrease in the blight. In April, 1899,
after the buds had begun to open, some experiments
were completed, using 0.20 gramme cyanide, upon
pear trees. The former tests had been made during

1 6 FUMIGATION METHODS

the fall, midwinter, and early spring, and now we took
up the effect of the gas on the trees in late spring as
the buds began to open?

Work upon nursery stock. — Experiments were also
performed the spring of 1899 upon nursery stock, for
the purpose of determining the precise effect of the
gas upon young trees used at a strength greater than
0.25 gramme cyanide per cubic foot. Owing to the
fact that some states stipulate by law that trees must
be fumigated, it became absolutely necessary that we
know definitely the effect of this gas upon growing
plants, especially dormant trees. No recent experi-
ments have been recorded along this line, as far as I
know. We have been using 0.25 gramme cyanide in
general work, and I recommend that strength for all
nursery stock above three feet in hight.

Apple trees. — We began our experiments with the
stronger doses March 29, 1899. The apple trees were
divided into twenty different lots of five trees each,
leaving five for a check. They were 4 to 5 feet
in hight, and of the following varieties : Ben Davis,
Northern Spy, L,imbertwig, Wealthy, Fall Pippin,
Oldenburg, Stark, Rome Beauty, Schockley, and York
Imperial. They were exposed in gas one hour, and
each lot was fumigated with 0.25, 0.30, 0.40, 0.45,
and so on, adding 0.05 to each one until we reached
i. oo, then skipped from i.oo to 1.25, 1.35, and 1.45
grammes, thus completing the series. The trees were
labeled and planted, and were under observations two
seasons.

The outcome of these experiments is as fol-

FIG. I — YORK IMPERIAL APPLE TREE, FUMIGATED WITH SIX
TIMES NORMAL STRENGTH OF GAS AND NOT INJURED

18

FUMIGATION METHODS

lows : I had fully expected that the gas would badly
injure the trees above 0.75. In fact, no apple trees
were injured in the least, even when exposed to 1.45
grammes, or about six times the normal strength,

FIG. 2 — OGON PLUM TREE, FUMIGATED WITH THREE TIMES
NORMAL DOSE

excepting one variety, Northern Spy. I can not ex-
plain why this was more susceptible to the gas in this
test than the others, as it is naturally a hardy tree,
and its resisting properties should be as great as Ben
Davis or any of the other varieties treated. The

PHYSIOLOGICAL EFFECTS ON PLANTS

condition of the Spy in general appearance was about
the same as the others, and the buds had just begun to

swell. The injury, evidently,

was not due to the gas, as sub-
sequent tests with normal doses
showed that no injury to North-
ern Spy resulted.

Figure i shows one of the York
Imperial apple trees in this ex-
periment, fumigated an hour in
gas representing nearly six times
the normal strength. The photo-
graph was taken July 31, 1899.
The growth was good and the
tree was in perfectly normal con-
dition when the experiment was
closed.

Plum trees, — Twenty plum
trees of the following varieties
were fumigated April 17 and
1 8, 1899 : Abundance, General
Hand, Genii, Lombard, Ogon,
Shipper's Pride, and Spalding.
The trees varied in hight from
2 to 4 feet. Bach lot had one
hour's exposure, with 0.35, 0.45,
0.55, 0.65, 0.75, 1.25, 1.35, and
1.45 grammes of cyanide. The
results obtained are very strik-
ing ; for instance, there was no damage whatever to
any varieties until 0.65 gramme was reached, when the
Spalding had terminals slightly injured, while General

FIG. 3 — OGON PLUM
TREE, FUMIGATED

20 FUMIGATION METHODS

Hand was not hurt. At 0.75 gramme Ogon had ter-
minals slightly injured^ as shown in Fig. 2, while
Spalding was killed to the ground, but later sent out
shoots at the base. At i.oo gramme Ogon was again
only slightly hurt, while Abundance was dead to the
surface of the ground. From i.oo to 1.35 Ogon was
slightly injured on the terminals, as can be seen in
Fig. 3-

The general conclusions drawn from these tests
with plum are (i) that no injury will result where
normal dose is used for one hour or less on well-
matured trees over two feet in hight, and (2) that
some varieties are more resistent to injury from over-
doses of gas than others.

Peach trees. — The experiments upon peach trees
were commenced April 26, 1899, after the buds had
begun to swell. There were 250 trees, one-half of
which were first-grade Peninsula Yellow, 4 to 5 feet,
while the others were very small, varying from i^
to 2 feet high. The trees were divided into lots of five
each, and both grades treated from 0.25 to 1.45
grammes cyanide per cubic foot, 0.05 gramme being
added each time. In every instance the short grade
trees, known as ' ' whips, ' ' were killed outright, or the
tops were killed, sending out few feeble shoots near the
ground later. This corresponded to results obtained in
1898, that June-budded peach and plum, and small whip-
like trees from i^ to 2^ feet, can not withstand more
than o. 1 8 gramme for half an hour. On the other
hand, with large trees there was no perceptible injury
from 0.25 gramme up to 0.50 gramme. At the latter
strength, double the normal, the terminals were injured

FIG. 4 — I'EACH TREE, FUMIGATED WITH NORMAL DOSE

22 FUMIGATION METHODS

slightly, as shown in Fig. 5, while a tree given a
normal dose, 0.25 gramme, is seen in Fig. 4. In 0.75
gramme the top was killed about one-third the way
down, as seen in Fig. 6. The engravings are self-
explanatory, and show the deadening effect with the
varying degrees of gas from the top downward. From
0.75 gramme to i.oo gramme it was variable. In
.some instances the whole top was killed. From i.oo
gramme up to the highest amount used, 1.45 grammes,
a curious fact was noticed. In almost every case the
injury was not as great above i.oo gramme as below
0.75 gramme. In 1.35 and even 1.45 the trees were
only slightly injured at the top, as seen in Fig. 7,
resembling the effects produced where 0.50 gramme
was used

June-buds, grafts, and buds. — Young peach and
plum trees, known as June-buds, should not be fumi-
gated with the stronger doses. Tests made in 1 898 show
that nursery stock of this kind will not withstand the
gas when generated with cyanide above o. 18 gramme
per cubic foot. Any wood not well matured is liable
to be injured if a greater amount of cyanide is used.
For stock of this character o. 16 to o. 18 gramme cya-
nide per cubic foot is recommended, at an exposure of
one-half hour and no longer. The scale, under ordinary
circumstances, is destroyed wrhen fumigated with 0.12
to o.i 4 gramme cyanide. The 0.15 to o. 18 formula
can be used with perfect safety on buds, grafts, and
scions.

Roses and other siipplies. — In fumigating roses and
other materials handled by florists the cyanide should

24 FUMIGATION METHODS

be reduced to o. 10 to o. 15 gramme cyanide. As a rule,
it is not desirable to fumigate such plants as cedars,
pines, etc.

Seeds of various kinds can be fumigated in nor-
mal amounts of gas with perfect safety, the varying
physiological effects depending upon the condition of
the grain or seed, whether dry or moist, upon the
amount of gas used, the length of time exposed, and
the atmosphere in which it is confined, whether dry,
damp, or saturated. This is treated more fully later
in another chapter.

Low-growing plants may be fumigated for the de-
struction of the root aphis, leaf-rollers, and other
insects, but the work must be done with the same care
as for other plants. Lettuce, cucumber, and canta-
loups are very easily injured if the plants are damp,
even with small amounts of gas. In tests made by Pro-
fessor K. D. Sanderson, of the Delaware Agricultural
Experiment Station, upon young cantaloups after a
shower, he found the plants were injured in 0.40
gramme of cyanide per cubic foot for ten minutes. Pre-
liminary tests should be made with o. 10 to 0.20 gramme
for ten to twenty minutes before an entire house is ex-
posed. Professor Sanderson has shown also that straw-
berry plants freshly dug and fumigated in a box will
withstand o. 20 gramme cyanide fifteen minutes. His
tests show that this strength will kill the aphids on the
roots and not injure the plants. Other details are given
in a later chapter on this topic.

CHAPTER IV
EFFECTS ON ANIMAL LIFE

O""lwiNG to the very deadly nature of hydrocy-
^^ anic acid gas if inhaled by animals, the
following instances are given as a warning
to those who may handle this material.

A fortunate accident happened in a fumigating
house which should be a signal warning to those who
may use this gas. The house had been filled with
Norway maple trees, and after the usual length of
time the doors were thrown open. At the expiration
of seven minutes a negro laborer, who had been re-
peatedly warned not to enter the room under ten
minutes, went in and began handing out the trees to
another negro standing at the door. He handed out
two bundles, and while stooping for the third fell
headlong on the floor. He was immediately pulled
out, laid on his back in the open air, recovered con-
sciousness in about fifteen minutes, and was seemingly
as well as ever in half an hour. When asked what
had happened and how he felt, he replied, " De I/ord
only knows dat stuff am a powf ul axfitter ! ' '

Another peculiar accident happened during our
experimental operations at Mr. Emory's. Our cyanide
having been shipped to us in lumps too large for use,
we found it necessary to break it up in smaller pieces.
In order to do this and keep it from flying, we covered
it with an old fertilizer bag. After the cyanide had

25

26 FUMIGATION METHODS

been removed from the bag and the smaller particles
shaken out, the bag was again shaken out the window
to free it of any particle's that may have remained.
As a result, a few small pieces, not larger than a pin's
head, were shaken on the ground. Two fine, large
chickens, especially prized by their keeper, roaming
about, picked up some of the cyanide, and in less time
than it takes to write this account they were on their
backs. One died in a very few moments, while the
other recovered, evidently not having gotten so much.

Professor Woods tells me that a favorite cat, asleep
under a bench in one of the greenhouses he fumigated,
was killed without being awakened. A dog was
placed in one of our fumigating houses to test the
effect of the gas upon animal life, after the room had
been opened and aired for seven minutes, and again
closed. The animal was removed after five minutes'
exposure in an unconscious condition, but recovered
in half an hour.

Frequently the writer has placed toads, frogs,
snakes, pigeons, sparrows, rats, mice, dogs, and cats
in some remote corner in buildings to test the thor-
oughness of the diffusion of the gas. In every case
the animal was dead when removed. Many instances
could be cited, but this will suffice our purpose in
warning those who use cyanide or hydrocyanic acid
gas that they are exceedingly dangerous substances
and must be handled carefully.

CHAPTER V
APPARATUS FOR USE IN ORCHARDS

T"!HE equipment necessary for orchard fumigation
depends largely upon the kind of trees to be
treated and the location of the orchard. In
California the sheet tent is in general use.
Another form, known as the bell tent, is also quite
commonly used in California orchards. Of the earliest
apparatus used, the Wolf skill fumigator was a good
type. It is a bell tent manipulated by a derrick
mounted on a wagon. It has an arm on each side
extending over the top of the trees when driven be-
tween the rows. This form of tent is lifted up by
means of a rope attached to the top and extending to
a loop at the end of the arm or derrick, through which
the tent is drawn as it is removed from the tree. This
form of tent is shown in Fig. 8.

Another form, known as the Titus fumigator
(Fig. 9), consisted of a smaller tent, supported by a
square frame braced at each corner and mounted on
wheels with a piece across the top, on which the tent
could be wound in removing it from the tree. Still
another form, known as the Culver fumigator (Fig.
10), consisted of two light frames, half-bell shaped,
covered with cloth. It formed a complete tent when
closed together around the tree. This form of fumi-
gator was simplified later and the cloth allowed to rest
on the sides of the tree. The Culver outfit, in con-

27

28 FUMIGATION METHODS

nection with the Morse f umigator, is shown in Fig. 1 1 .
All the earlier forms q£ fumigators were provided
with generators and blowers. They have all been
superseded by different forms of tents better adapted
for orchard work.

To meet the general conditions in the East and
other places, I have perfected still another form, which
has been called the Kmory fumigator, and is shown
in Figs. 32 to 35. On large orchard trees the sheet
tents are better adapted for general work than the box
tents. The Emory fumigator is especially adapted for
trees under ten feet in hight.

The canvas or sheet tent. — The octagonal form
known as the sheet tent has been used largely in
California and by the United States Department of
Agriculture. The size of these tents depends upon
the size of the trees to be fumigated. Sheets from
twenty-five to forty feet and over in diameter are in
common use. One tent used in my experiments was
forty-five feet in diameter and was used only on large
trees. Another canvas tent, made in several sections
with a square top and base, designed by R. S. Emory,
is shown in Fig. 12. These tents vary in size to meet
the requirements under different conditions in various
orchards. A very convenient size of canvas-box tent
is fifteen feet square at the bottom, ten feet square at
the top, and fifteen feet high. Occasionally tents of
this same design of much smaller dimensions are used,
but they are not generally recommended.

Construction of tent. — All tents now in general use
are usually made of eight-ounce cotton duck, such as

FIG. 8 — THE WOLFSKILL FUMIGATOR

FUMIGATION METHODS

is used by the Army and Navy for tents and light sails.
With little care any awning or tent maker can cut the
sheet tents so there is practically no waste in material.
They are usually cut and made into quadrants and then
put together. The center in the large tents is usually

FIG. 9 — THE TITUS FUMIGATOR

double for a space of about two feet in diameter, as
there is considerable strain upon the material at this
point. A half-inch or five-eighths inch rope should be
hemmed in around the edges.

The cost varies according to the size, and the
expense of oiling must be added. All tents should be
thoroughly oiled by painting them with boiled linseed
oil. Usually one or two coats will be sufficient. The

APPARATUS FOR USE IN ORCHARDS 3!

following quotations, including oiling, were secured
from a Baltimore, Md., tent-maker :

Sheet tent, with square top and base, 4x 5x 2 ft. . . $2.00
" " " 7 x 10 x 4 " . . 7.00

" " " " " " " 10x15x15" . . 12.50

" " octagonal form, 25 ft. in diameter .... 18.00

" " " 30 " .... 25.00

" 45 " " .... 42.00

FIG. 10 — THE CULVER FUMIGATOR

In constructing tents the cloth is lapped and doubly
sewed in the same manner as for tents or sails. The
edge can be either hemmed or bound with rope. If
permanent rings for handling are attached the tent
may need reinforcement. The general details of the

32 FUMIGATION METHODS

construction depend somewhat upon the persons doing

the work.

•

Oiling and painting. — In order to make a tent
gas-tight it is necessary to cover it with oil, paint,
or other material. Several methods are in general

FIG. II — CULVER TENT AND MORSE FUMIGATOR

use for this purpose, all of which have been used
with considerable satisfaction. A free application
of boiled linseed oil is, perhaps, the method most
commonly used. After the tent is thoroughly satu-
rated with oil it should be spread out or tacked to the
side of a building where it can dry. Care must be

APPARATUS FOR USE IN ORCHARDS 33

taken that the oil is thoroughly dry, otherwise it has
a great tendency to generate heat if the tent is folded
and left for any length of time. The cloth burns or

FIG. 12 — CANVAS TENT WITH SQUARE TOP AND BASE

chars and is ruined. On the other hand, if the tent is
thoroughly dry after oiling, it is easily handled and can
be folded with per feel: safety.

In some cases paint is used. It is applied with a
brush in the same manner as the oil and penetrates the

34 FUMIGATION METHODS

cloth, filling the fiber in the same way, making it
when dried thoroughly gas-proof. As soon as the
paint is dry the sheet is covered with another coat of
rather flexible paint. When dry this coating makes a
perfectly tight tent, with a smooth surface and quite
as flexible and easily handled as the oiled tent.

Still another method is used in some places. A
decoclion is made by filling a barrel two-thirds full of
chopped stems and leaves of the common prickly pear
cactus {Opuntia engelmani). Afterward the barrel is
filled with cold water and is allowed to stand twenty-
four hours. The liquid is then drawn off and ready for
use by adding a pigment, like yellow ochre or Venitian
red. Sometimes a small quantity of glue is added.
To prevent molding when not in use and folded, a small
quantity of tannin solution is added to the mixture.
This solution can be applied to the tents with a brush,
but where a sufficient quantity is on hand it is better
to soak the sheets over night in a vessel containing the
mixture. They should then be taken out of the
material, thoroughly drained, and spread out to dry.
This method, however, is not generally used, but has
given very satisfactory results, as the cloth is not
stiffened, and is made quite flexible and easily handled.

CHAPTER VI
BELL AND HOOP TENTS

T|HE tents known as bell tents are cylindrical in
shape, with the top rounded over like a dome.
They are used in connection with a derrick,
by means of which they are placed upon and
lifted from trees; the derrick also supports the weight of
the tent while it is upon the tree. The bell tent was one
of the original forms of tents, and while mostly sup-
planted by other styles, is still used to a considerable
extent, especially for very large trees. It is the only
form of tent now in use where the whole weight of the
tent is not carried by the tree, and many favor it for
this reason.*

The derrick used with the bell tents at the present
time is that used with the Preble fumigator, or some
modification of it. This is shown in Fig. 13. It con-
sists of a wagon, which supports a mast considerably
higher than the trees to be fumigated, and is braced at
the bottom with stays that hold it rigidly in place.
Across the top of the mast a yard is fastened and
braced with trusses extending from the mast. The
length of the yard is about a third longer than the
distance between the rows of trees. Near each end of

* This description is taken from the excellent bulletin
(No. 122) by Prof. C. W. Woodworth, of the California
Experiment Station.

35

36 FUMIGATION METHODS

the yard are placed cross-bars, as shown in the illus-
tration. The arrangement of the ropes can be under-
stood from a study of the figure.

The heaviest rope is attached to the top of the tent
with double pulleys. Along the lower edge, on the

FIG. 13 — THE PREBLE FUMIGATOR, AS USED IN
CALIFORNIA ORCHARDS

four sides of the tent, are fastened boards, generally of
ordinary six-inch fencing, which are called trail boards,
and from the center of each of these the trail ropes
pass upward and over pulleys attached to the yard and
ends of the cross-bars. All these ropes follow the
yard till near the mast, then passing again over pul-
leys, they go down to the bed of the wagon and are
fastened over belaying-pins. The trail ropes pass

AND HOOP TENTS

37

through thimbles along the side of the tent as well as
through the pulley at the center of the trail, so that
when the latter is drawn up to the yard, or cross-bars,
the sides of the tent are gathered in three or four
places and raised almost as high. The only other
ropes are the guide lines attached to the center of the

FIG. 14 — RAISING SMALL HOOP TENT

trails and hanging free. They are of such length
as to reach the ground when the tent is elevated.

The manipulation of these tents can be readily
understood from a study of the engraving. While
the tree is being fumigated the tent is usually allowed
to rest partly on the tree and not drawn up to the
yard, as shown in the illustration. Two persons can
handle the apparatus, but three or four greatly facili-
tate the work. The procedure in changing the tent is

38 FUMIGATION METHODS

as follows : Supposing that both tents are upon the
trees and the time has Arrived to make the change,
the first operation is to pull on the main rope attached
to the center of the tent and raise this as far as it will
go easily, and then fasten the rope again to the belay-
ing-pin. If short-handed, one tent is raised at a time,

FIG. 15 — SMALL HOOP TENT ALMOST IN POSITION

but with plenty of help both go up at the same time.
The trail ropes are next taken in hand and pulled all
together, and if this becomes difficult, two (or even
one at a time) are pulled until the tent on all sides is
pulled up to the yard and cross-bars.

While this is going on, one person (or perhaps
more) is kept busy seeing that the tent is clearing the
tree properly. His first business is to see that the

AND HOOP TENTS 39

edge with the trail boards is not caught inside of the
tent; it should slip up around outside of it. L,ater he
will be occupied with making the tent slip off the pro-
jecling branches. He can generally do this by pulling
on the guide lines, but on very large trees he may find
a light ladder necessary. The removal of the tent

FIG. l6 — SMALL HOOP TENT READY FOR CHEMICALS

would be comparatively easy but for the work at the
ropes. After all the ropes are pulled tight, including
the main rope, and both tents are against the yard, the
apparatus is ready to shift to the next row. The
wagon may be pulled along by hand, or by a horse
hitched to the end of the tongue. If the ground is a
little uneven, the apparatus can be kept from tipping
over by steadying it with the guide lines. Arriving

40 FUMIGATION METHODS

at the proper position between the next two trees, the
first thing is to arrange the guide lines in their places
around the tree. The trail ropes are now released and
the tent is allowed to slowly descend upon the tree.
While this is taking place, one or more are busy with

FIG. 17 — LIFTING LARGE HOOP TENT FROM GROUND

the guide lines, pulling the trail boards this or that
way as may be necessary to clear the branches.

If a branch is particularly spreading it may be
necessary to use a ladder, forcing it within the tent by
hand. Should the trees be very large the branches
will extend over the wagon, causing much trouble in
pulling the tent down on that side. With a small,
symmetrically shaped tree the tent can be lowered rap-
idly into place without any trouble whatever. After

BEU, AND HOOP TENTS 41

the trail ropes are all played out, the main rope is
loosened and the tent allowed to settle to the position
desired, and fastened there. There yet remains the
job of seeing that the tent is tight to the ground on all
sides. The trail boards are made to lie on the part of
the tent that is on the ground, and earth is thrown on

FIG. IS — ADJUSTING LARGE HOOP TENT

any part of the edge of the tent that does not lie down
well. When both tents are thus in position they are
ready for the man who charges the generator.

The hoop tent. — The form most used in California is
the hoop tent, which is a development from the bell
tent, and is of the same general shape. The hoop was
first used as a means of keeping the mouth of the bell
tent open, but it was soon discarded in favor of the

42 FUMIGATION METHODS

trail boards. It was, however, discovered that for
rather small-sized tents yie hoop afforded a better
means of handling than did the derrick.

The hoop tents now in use range from eight to
fourteen feet in diameter. They are made in the same
way as a bell tent, omitting, however, the arrange-
ments for suspending them, and possessing, instead, a
series of cloth loops for attaching the hoop, as is shown
in the engraving.

The hoop is usually made of three-quarter-inch gas-
pipe; half-inch pipe will do for the smaller sizes, but it
is too weak for hoops above ten feet in diameter, as it
bends too easily and soon becomes very crooked. To
make the hoop, pipe is coupled together until the proper
length is reached, according to the size desired, and
then bent into shape. The union is then made by in-
serting into the ends a piece of iron rod a foot or less
in length and just small enough to enter the pipe.
Holes are now drilled through the pipe and rod, and
rivets are inserted, thus making the joint fast. A
coupling with right and left hand threads might be
used instead of the rod and rivets.

The manipulation of a hoop tent varies according
to its size. When the diameter of a tent is not much
greater than the distance between the nearest branches
of adjacent trees, the procedure is that illustrated in
Figs. 14-16.

To move such a tent from one tree to the next, two
men place themselves on opposite sides of it, grasp the
hoop, and raise the side which is opposite the tree to
which they intend to move it ; they step sidewise,
dragging the side that is on the ground closer to the

AND HOOP TENTS 43

trunk. The men, still holding the hoop as they first
grasped it, continue to raise the free side until it
passes over the top of the tree, when it is allowed
to fall to the ground between the two trees. In
falling, the hoop naturally moves away from the tree
from which it came, so that the cloth falls over the

FIG. 19— LIFTING TENT AFTER FUMIGATION

edge of the hoop. If this does not occur, the tent
is pulled into that position in order that, when
the hoop is raised, the center of the tent will be
brought at once to about the center of the top of the
tree.

The men now grasp the hoop again, as before,
carry it toward the tree and lift up the further edge,
then with one movement throw it over the tree. Often
it will go clear to the ground and needs no further

44

FUMIGATION METHODS

attention. The cloth which extends beyond the hoops
forms a sufficiently tight contact with the ground if
the latter is ordinarily level.

The manipulation of the large hoop tents differs
from that above described, from the fact that the

FIG. 2O — COVERING TREE WITIP LARGE HOOP TENT

proximity of the trees makes it impracticable to lay the
tent on the ground. The procedure in this case is
indicated by Figs. 17-20 and in the accompanying
diagram, Fig. 21.

It is better to have three men handle these tents,
though two can do it. When working three, two
take hold in the same way as described above for the
small hoop tents, and the third pulls on the side
that is raised. The latter then catches the hoop with
a fork at the end of a pole, and as the others lift

OBELI* AND HOOP TENTS 45

he assists by pushing. This is shown in Figs. 19
and 20.

When the hoop has taken about the position shown
at B, in Fig. 21, or a little past that point, the two
men holding the sides of the tent carry it to the next
tree to the position C, and then without pausing, and
while the tent is full of air and streaming out behind
with the aid of momentum acquired, the upper edge

FIG. 21 — DIAGRAM ILLUSTRATING METHOD OF SHIFTING
LARGE HOOP TENT. (AFTER WOODWORTH)

of the hoop is forced over the top of the tree and down
on the other side. Generally it is possible to throw
the hoop into the position D, when it can readily be
pulled down to the ground.

If there is any trouble in pulling the cloth over, the
third man, having tossed his pole to the next tent, goes
around to the near side of the tent just moved, and as
the others pull on the far side, shakes the cloth of the
tent away from the tree, thus relieving some of the fric-
tion. The weight of the hoop of these large tents greatly
helps in the process of slipping the cloth over the tree,

46 FUMIGATION METHODS

the most energy being required in removing the tent.
The large tents are ino^fed quite as rapidly as are the
smaller ones. It will be noticed that the cloth is
turned inside out with each change in the case of the
larger tents, but with the smaller ones the same side
of the cloth is always next to the tree.

CHAPTER VII

CONSTRUCTION AND MANAGEMENT OF SHEET
TENTS

T~!HERE are many methods used for handling
sheet tents in orchards. A single pole, such
as shown in Fig. 24, is very useful. The
pole is known as a " lifter, ' ' and consists of
an eighteen-foot yellow pine sapling, thoroughly sea-

/!\\

/ 4 \«. *

/ ft \ N!

" % -

FIG. 23 — MANIPULATING SHEET TENTS WITH A SINGLE POLE
(AFTER WOODWORTH)

soned, such as is used on ordinary sail-boats. It
should be about four inches in diameter at the base,
tapering to about three inches at the top. Such a pole
is strong, light, and very durable. A piece of 3 x 4
inch scantling is nailed at the base and braced, as
shown in the illustration. A small block pulley,
large enough to carry a five-eighths inch rope, is
screwed near the top of the lifter. Forty to fifty feet
48

FIG. 24 — METHOD OF COVERING A TREE WHEN A SINGLE
POLE IS USED

50 FUMIGATION METHODS

of half or five-eighths inch rope will be needed in the
pulley. This is called the "pulley rope." A cleat
should be attached to tne side of the lifter about five
feet from the ground. The pulley rope is attached to
this when the tent is hoisted. Another piece of rope,
twenty-five to thirty feet in length, should be tied near

FIG. 25 — REMOVING SHEET TENT BY MEANS OF POLE AND
HELPERS

the top of the lifter above the pulley. This is called
the "stay rope." The lifter is kept in place by
means of the stay rope by tying it to an adjacent tree,
as illustrated.

Various other appliances will be found helpful.
Usually the conditions will suggest some improvement
whereby the tents can be handled more easily. A
hand pole, such as is shown in Fig. 25, can be used to
good advantage in tenting and untenting a tree. This

52 FUMIGATION METHODS

is known as the ' ' helper, ' ' by means of which the
weight of the tent can be kept from the tender
branches of the tree. The helper shown in the illus-
tration gives a good idea of the construction and its
method of use. In this particular case the tent is
being removed from the tree which has just been
fumigated.

To tent a tree where a single lifter is used, it should
be set at an angle of about sixty degrees and the stay
rope fastened to an adjoining tree, thus holding it in
place, as shown in Fig. 23. One end of the pulley rope
is then passed around the tree and tied to the tent lying
on the ground on the opposite side. The operator at the
lifter then draws the tent to the pulley and fastens the
rope. He then steps back a few feet, and, taking the
stay rope, pulls the lifter to\vard himself until the
center of the tent is about over the top of the tree, as
shown in Fig. 24. In the mean time the other assist-
ant brings the sides of the tent around toward the
lifter. The operator takes one side while the assistant
holds the other, as shown in the illustration. When
the lifter is at the proper angle to bring the center of the
tent over the top of the tree, one side of the tent is
then passed to the assistant between the lifter and the
tree, while the operator loosens his pulley rope and lets
the tent fall in position over the tree. The assistant
unties the stay and pulley ropes and carries the lifter to
the next tree, while the operator banks the tent or folds,
the cloth around the base of the tree. Often a few
shovelfuls of earth are necessary to hold the bottom of
the tent in place, if there is not a sufficient amount of
canvas to fall on the ground. If the wind is blowing

54 FUMIGATION METHODS

and the tent is a little slack a few pieces of stone or
chunks of wood may be required to hold it down.

When the trees are uniform in size as many rows
are taken as there are tents in use. The sheet tents
are then transferred from tree to tree by simply revers-
ing them over and over again. The method varies
from the foregoing only in the fact that the pulley
rope is carried around the side opposite the lifter and
fastened to the bottom of the tent covering the trees.
The lifter is also set at a more acute angle. The can-
vas tents with square tops, however, can not be re-
versed in this manner. In such cases they are taken
from the tree, lowered, and again hoisted in the usual
manner. The method of untenting a tree in an Eastern
orchard is shown in Fig. 25. On very large trees two
lifters are usually necessary, and in this manner the
weight of the tent can be kept almost entirely from
the branches.

California outfit. — In addition to the descriptions
of the apparatus already given from California, Figs.
26-29 will be °f interest. These photographs were
furnished by R. B. Cundiff, chairman of Riverside
County Board of Horticultural Commissioners, and
were taken for the United States Department of Agri-
culture for the Year-Book of 1900. It will be seen
by the figures that these tents are of enormous size
and are handled by two lifters, one on each side of the
tree, Figs. 26 and 30. The tent is pulled into position
very much in the same manner as already described.
After the tree is covered, as shown in Figs. 27 and 31,
the canvas is folded around the base and the gas is
generated. A novel feature of the outfit used in the

CONSTRUCTION AND MANAGEMENT OF TENTS 57

Riverside district is, that the tents are removed by
means of a horse, as shown in Fig. 28. In transport-
ing these tents and the apparatus, a low-wheeled

FIG. 3O — TENTING AN ORANGE TREE IN RIVERSIDE DISTRICT,
CALIFORNIA

wagon is used on which the entire outfit is packed, as
shown in Fig. 29.

When using a large tent for a very small tree, the
tent is pulled up so as to have sufficient slack canvas
to cover the tree. This is usually pulled over by
hand. When being removed, the cloth is pulled back

FUMIGATION METHODS

FIG. 31 — TENT IN POSITION, ABOUT READY FOR CHEMICALS

in the same manner and dragged along the ground to
the next tree. Where there is fear of breaking the
branches in removing a large tent, the weight is
usually taken off by means of the lifter. The tent, by
this method, slides over itself and protects the tree.
It is transferred from tree to tree in accordance with
the methods already described.

CHAPTER VIII
EMORY FUMIGATOR WITH MODIFICATIONS

FTKR much experience with sheet tents in East-
ern orchards, and while confident the gas
could be used to good advantage, it was evi-
dent to the writer the method would have to
be simplified before it could be used by the average
fruit grower. The main difficulty was in the calcula-
tion of the cubic contents of a tented tree and the
measurement of the chemicals afterward. The folds
in a tent over a tree are so extremely variable it is
almost impossible to calculate the cubic contents, even
approximately. As the success attained by this
method depends entirely upon the exactness with
which the operation is performed, it was therefore
necessary to find a system less variable for deciduous
trees.

First of all, a method by which the cubic contents
could be kept nearly constant, and one that could
be applied without the wear and tear upon the
tree by the tent, resulting in the destruction of so
many fruit and leaf buds, was desirable. After much
thought and consideration, it seemed that both ob-
jections to the sheet tent system could be overcome by
the construction of a box with a square base, varying
in hight to suit conditions and having a canvas hood.
It was also necessary to cheapen the cost of the equip-
ment, if possible.

lyight wooden frames were constructed and covered

59

6o

FUMIGATION METHODS

with heavy rawhide building paper. The largest box
was six feet square at the base and eight feet high, as
shown in Fig. 34. It was put together with three-
inch butt hinges, and could thus be easily opened by
drawing the butts from one side. The hood is made

FIG. 32 — MODEL TYPE OF EMORY FUMIGATOR WITH HOOD
FULLY EXTENDED

of eight-ounce ducking, and is six feet four inches at
the base, four feet square at the top, and seven feet
high. It is kept in place by means of cleats around
the top of the frame, as seen in Figs. 33 and 34.

62 FUMIGATION METHODS

The hood is first placed over the top of the tree,
•after which the frame is. drawn around and closed.
After the bottom of the hood has been securely fast-
ened to the top of the box and a little dirt has been
thrown around the bottom, the frame is tipped back
slightly and the chemicals are introduced. At the ex-

FIG. 34 — EMORY FUMIGATOR, PAPER TYPE, COMPARED WITH
SHEET TENT

piration of the proper time the hood is removed,
the box opened and slipped around the next tree.
Boxes under six feet in hight were constructed with-
out hoods and the sides screwed together. These can
be handled easily and can be used on small trees,
where it is not practicable to use a tent.

It was slow work and troublesome to place the
hood, arrange the box, and get it ready for operation
each time. The system, however, was as near perfect:

64 FUMIGATION METHODS

as we could expect it, and we began work to overcome
the two serious objections. First, a box with a per-
manent hood, and, seconcfty, one that could be handled
without being opened on the sides was needed. At the
same time, while we found the rawhide paper perfectly
satisfactory on the large box, it was quite trouble-
some to put on the frame smoothly. The edges were
first glued and then nailed. It was also easily punc-
tured by a broken limb unless great care was taken.
This last point was not a serious objection, and little
or no trouble was experienced on that account. A
material, however, with more elasticity was desir-
able.

Taking all these points into consideration, a box
of the same dimensions, covered with eight-ounce
ducking, was constructed. The sides were screwed to-
gether, and the hood fastened on permanently with
narrow strips screwed to the top of the frame, as
shown in Fig. 32.

Having completed this box, the most serious obsta-
cle arose. How could a box of such dimensions, with
permanent hood and sides, be handled ? There was
only one way to do it, and that was to pick the box
up and lower it over the top of the tree. The prob-
lem was solved by the ingenuity of Robert S. Kmory.
It was accomplished by means of a thirty-five foot
mast made of spar pine and a twelve-foot gaff of the
same material. It was fitted with ropes and pulleys,
and rigged to the running-gear of an ordinary farm
cart, as shown in Fig. 35. By means of this it could
be raised and lowered over any tree under seventeen
feet in hight. The system worked perfectly, and was

66 FUMIGATION METHODS

applied in a block of infested pear trees the first and
second week in April, 1899.

It requires three or*four men to operate an outfit
of this kind ; the help, of course, depending on the
number of fumigators in use. It requires one man to
look after the chemicals and time, and two or three to
handle the fumigators and rigging. With an equip-
ment of ten fumigators this force, under favorable
conditions, can in one day fumigate from one hundred
and seventy-five to two hundred trees, varying from
twelve to seventeen feet in hight. The cost of the
chemicals is about four cents for the eight-foot box
without the hood extended, five to six cents when the
hood is half extended, and six to seven cents fully ex-
tended.

The cost of the large fumigator complete, as seen
in Fig. 32, is about $12, or about two-thirds that
of a twenty-five foot sheet tent sufficient 'for covering
a tree of the same size. The rigging for handling the
fumigators costs about $12. Taking it all in all,
this system is simple and can be used by the average
orchardist.

In giving this method for handling hydrocyanic
acid gas to the public, it should be said that the author
has had the practical experience of Robert S. Emory,
of Maryland, without which it would not have been
possible to have completed the experiments and per-
fected the apparatus. The mechanical details were
under his entire personal supervision. As a slight rec-
ognition of his services and practical experience, this
apparatus has been named the ' ' Emory Fumigator. ' '
The Miller type. — The Emory fumigator has been

68

FUMIGATION METHODS

modified somewhat by H. W. Miller, of West Virginia,
types of which are sh(*vn in the accompanying illus-
trations. It is constructed for use in orchards, where
the trees are eight to ten feet high. These fumigators

FIG. 38 — PLACING FUMIGATOR OVER TREE.
APPARATUS FOR CHEMICALS

TRAY AND

are five feet square and seven feet high, with flat top.
A light wrooden frame is first made, around which
three breadths of eight-ounce ducking (carefully sewed
together) is wrapped and tacked along one edge with
tin heads, such as are used for holding building paper
in place. The top piece of cloth is also tacked around

EMORY FUMIGATOR WITH MODIFICATIONS

69

the upper edge in a similar manner. The cloth is
then thoroughly painted with boiled linseed oil and
allowed to dry. Two coats are given if necessary, one
being applied to the inside.

To facilitate the handling of these fumigators two

FIG. 39 — FUMIGATOR NEARLY IN POSITION

strips of wood are nailed on opposite sides, as shown in
Fig. 38 and others. At the top, near the center, a
piece of half-inch rope two to three feet in length is
tacked, with which the operator can easily tip the tent

7O FUMIGATION METHODS

forward, allowing the gas to escape before the appara-
tus is transferred from »ne tree to another.

With an equipment of fifteen fumigators of this
type three hundred to four hundred trees can be cov-
ered in a day at a cost, including labor and chemicals,

FIG. 40 — PLACING THE CHEMICALS UNDER FUM1GATOR

of about six cents per tree. For an outfit of this char-
acter in mountain orchards, where the ground is rough,
ten men are necessary to manipulate it to best advan-
tage. Three men handle the boxes, as shown in Fig.
39. It also requires three individuals to shovel the
earth around the base of the f umigator, as seen in Fig.

EMORY FUMIGATOR WITH MODIFICATIONS 71

40. Two men attend to the chemicals, weighing the
cyanide and measuring the acid and water, as shown
in Fig. 40. In this particular case one man was em-
ployed to level the ground around the trees, so as to
facilitate the handling of the fumigators. A general

FIG. 41 — AIRING THE FUMIGATOR JUST BEFORE REMOVAL

foreman and timekeeper was necessary, so that the
boxes could be transferred at the proper time and
without delay.

The cost of the fumigator of this type need not ex-
ceed $5, including oil, provided the work is done at
home. The outfit illustrated in Figs. 36 and 37 is a
home-made construction. After using fumigators of
this type the canvas can be easily removed and used

72 FUMIGATION METHODS

for other purposes in orchards and farm work. In
some cases the sheets are used to cover fruit in wagons
as it is hauled to the station. The frames are put to-
gether with nails or screws, and are easily taken to
pieces and stored away for future use. This type of
f umigator is valuable for small trees and shrubs in or-
chards and on private grounds. The method of oper-
ating this type of fumigator is shown in Figs. 36 to
42, taken by the author expressly for this work.

A box fumigator. — A new style, much after the
old type of the Emory fumigator, has been designed by
Prof. V. H. Lowe, of the New York Experiment Sta-
tion. It is intended for use with the smaller orchard
trees, such as peach, pear, plum, and quince. A good
idea of the general construction of this apparatus can
'be gotten from a study of Fig. 43. The dimensions
are 10 x 6 x 6 feet. The frame consists of well-sea-
soned pine strips three inches wide and seven-eighths
inches thick, braced on three sides by double cross-
pieces of the same thickness and one and one-fourth
inches wide. The base is made of four-inch strips
and has but three sides, the fourth being omitted to
avoid the necessity of lifting the generator from the
top of the tree before putting it in place. The frame
is covered with eight-ounce ducking, such as described
for the Emory tents and other fumigators. The cloth
was oiled with boiled linseed oil, in which lampblack
was mixed to give it a dark color. To prevent trees
from penetrating the top of the fumigator a stout wire
netting was tacked on the inside of the upper half of
the frame.

A strip of canvas one and one-half feet wide was

EMORY FUMIGATOR WITH MODIFICATIONS

73

attached to each side of the base of the frame. The
strips lap at the corners, so that when the fumigator is
in place they lie on the ground and can be covered
with dirt or sand-bags, thus preventing the escape of

FIG. 42 — TRANSFERRING THE FUMIGATOR

the gas. These strips can be hooked up and kept out
of the way when the fumigator is being carried from
one tree to the other. The movable side of the fumi-
gator can be easily put in place or taken off. It is

EMORY FUMIGATOR WITH MODIFICATIONS 75

provided with four handles, as shown in the illustra-
tion. There is a two-inch flange covered with a good
quality of felt, against which the door rests. The sur-
face of the frame which rests against the flange is cov-
ered with the same material. There are two flat
pieces projecting on each side from the base of the
frame upon which the door rests. There are thirteen
buttons by which the door is fastened and kept in
place, as illustrated.

The cost of a fumigator of this size varies from
$13 to $18, according to the material used in its
construction. This fumigator has been severely tested
at the New York Experiment Station and found
very satisfactory. The time required for moving it
from one tree to another varies somewhat with con-
ditions, but as a rule it can be set up in from ten to
fifteen minutes. It can be operated and easily carried
by two men. A fumigator 12x8x8 feet, built accord-
ing to this style, would no doubt be practical, and
would require about three men to handle it. The re-
moval of one side prevents the necessity of lifting it
over the tree, as is the case with the Emory type.

CHAPTER IX
ESTIMATING GAS FOR ORCHARD WORK

A

MOUNTS OF CHEMICALS. — The foreman or super-
intendent should be responsible for the chem-
icals used for making the gas. As a rule,
where the sheet tents are used, different
amounts are necessary for individual trees, espe-
cially where they vary in size. The superintendent
judges the size of the tree as soon as it is tented,
and estimates and weighs the chemicals accord-
ingly. It is difficult to estimate the cubic contents
of a tented tree, and as a result some unsatisfac-
tory work is done. Indeed, it is surprising that the
results are as uniform as they are. In California the
trees to be fumigated are usually inspected in advance,
so that the superintendent can, in a general way, esti-
mate the amount of gas necessary. A little more gas
than the tree will stand without injury is usually pro-
duced. This is somewhat misleading, for the larger
the tree the greater the injury. If the dose is properly
proportional to the cubic content, there is a slower
diffusion of the gas, in which case care must be taken
when large trees are fumigated.

The usual method is to measure the tree and find
the amount of chemicals necessary -by reference to a
table prepared for that purpose. If the tables are cor-
rectly calculated and the measurement accurately done
this is perhaps the safest method. As already indi-
76

ESTIMATING GAS FOR ORCHARD WORK 77

cated, it is difficult to measure and determine accurately
the cubic content of a tented tree. To simplify the
measurement and estimation of the tent the following
table has been prepared by Prof. Woodworth, of Cali-
fornia. The center column gives the various doses
corresponding to the size of the trees in the columns
on either side. Thus, on one side it has been calcu-
lated so as to give three parts of hydrocyanic acid gas
in 1000 parts of air ; on the other side, two parts in
1000 of air. For winter treatment for deciduous trees
the first or 0.3 per cent, gas is suggested. This is
about equivalent to the general recommendations given
for the Eastern States. One-half of this amount is not
far from the commonest practice in California for
citrus trees. The 0.2 per cent, formula is suggested
for citrus trees. It agrees with the amounts used by
some of the most successful fumigators in California.
Other individuals get fair results with scarcely more
than half this amount.

The measurements to be taken when using this
table are (i) around the tent, and (2) from the
tent from ground to ground. If these two measure-
ments are about equal, as will be found on many
orange trees, the number nearest the measure-
ment is found in the circumference column, and
the corresponding dose will be seen in the center
column. If these two measurements are not nearly
the same, the outside columns become useful, for
they show for each size how much difference must
occur to make necessary a half ounce increased or de-
creased in dose ; that is. for each differential there must
be added or deducted one-half ounce of cyanide. For

FUMIGATION METHODS

instance, if the difference between the distance over
and around the tree is fivejeet, and the differential for
the circumference is three feet eleven inches, then the
dose must be increased or diminished by a little more
than a half ounce ; but if the differential is one foot,
then for each foot there must be added or subtracted
one-half ounce, or two and a half ounces for the five
feet.

CYANIDE NECESSARY FOR TREES OF VARIOUS SIZE&
IN CALIFORNIA

0.3 PER CENT. GAS

CYANIDE

0.2 PER CENT. GAS

^ Ounce
Differential

Circu mferen ce
of Tree

Circumference
of Tree

1^ Ounce
Differential

Ft. In.

Ft. In.

Ounces

Ft. In.

Ft. In.

3 5

19 1

2

22 1

3 11

3

20 6

2/^3

23 7

3 4

2 7

21 11

3

25

2 11

2 4

23

26 4

2 8

2 2

24 1

4

27 7

2 6

1 11

25 1

4Vi»

28 9

2 4

10

26

5

29 10

2 2

9

26 10

51^

30 9

2

8

27 8

6

31 8

1 10

7

28 5

32 7

1 9

6

29 1

7

33 4

1 8

5

29 9

7^

34

1 7

4

30 4

8

34 8

1 6

3

31 6

9

36 1

1 5

2

32 7

10

37 5

1 4

1

11

38 7

1 3

34 8

12

39 10

1 2

11

35 7

13

40 11

1 1

10

36 6

14

41 11

1 1

10

37 5

15

42 10

1

9

38 3

16

43 9

11

9

39

17

44 8

11

8

39 9

18

45 7

10

8

40 5

19

46 5

10

7

41 2

20

47 3

10

7

42 8

22

48 9

9

7

43 11

24

50 2

9

6

45

26

51 6

8

6

46 1

28

52 8

8

6

47 2

30

54

7

5

48 2

32

55 3

7

ESTIMATING GAS FOR ORCHARD WORK 79

As an example, Professor Woodworth cites a tree 35
feet around and 36 feet over the top, using the 0.2 per
cent, table. Running down the circumference column
we find that 34 feet 8 inches (the nearest to 35 inches)
requires 8 ounces, and that the differential is i foot
6 inches; that is, 35 feet requires a little over 8 ounces,
and the difference between the two measurements
around and over the tree, i foot, is nearly enough to
require another half ounce, so that S}4 ounces would
be about right. Suppose, again, the distance around
a tree to be 40 feet, and that over the top only 35 feet;
using the same table, we find opposite 39 feet 10 inches
(the nearest to 40 feet) the dose 12 ounces. But the
distance over the top is 5 feet less, and a less amount
of cyanide will be necessary. We therefore use the
differential (i foot 2 inches) and deduct one-half
ounce for each i foot 2 inches difference, or about 2
ounces altogether. This leaves 10 ounces as the correct
dose for this tree. These measurements are not sup-
posed to be taken with every tree, but in cases of
doubt, and occasionally to correct one's judgment;
and in the case of those beginning to fumigate, whose
judgment is not yet developed.

The three tables following are taken from an
excellent article on fumigation in the Rural Cali-
fornian. Effectiveness demands accurate judgment as
to the quantities of the chemicals to be used. This
must necessarily vary according to the cubic space to
be filled with gas, or, in other words, according to the
size of the tree. The tables here given, based on the
hight and width of tree, will be found quite practicable,
but in order to eliminate as far as possible errors of

8o

FUMIGATION METHODS

judgment regarding the dimensions of the trees to be
fumigated, a stick marked off in feet will be of assist-
ance.

QUANTITY OF CHEMICALS TO DESTROY BI^ACK SCAI,E ON
CITRUS TREES

HIGHT

Diameter

Water

Sulphuric Acid

Cyanide

Feet

Feet

Ounces

Ounces

Ounces

6

4

2

1W

V&

8

6

5

1/4

1/4

10

8

7

2

2

12

10

12

3

4J^>

12

14

18

4/^J

4^i

14

14

20

5 "

5

16

16

24

5Jx>

5Vij

18

16

24

6

6

20

16

26

6/^

6}^

22

18

30

714

7/4

24

20

88

8

8

26

20

88

8^6

8J4

30

20

35

8^

m

The proportions of chemicals used for citrus trees
affected with red, brown, or purple scale are given in
the following table. The same quantity may be used
for deciduous trees infested with San Jose or black
scale.

CHEMICALS FOR RED, BROWN, AND PURPLE SCAI.E

HIGHT

Diameter

Water

Sulphuric Acid

Cyanide

Feet

Feet

Ounces

Ounces

Ounces

6

4

3

lur

3^

8

6

7J4

1%

1%

10

8

»y%

3

3

12

10

18

4J*ij

4/^j

12

14

27

0%

6M

14

14

30

7^3

7J^

16

16

36

8j4

8^4

18

16

36

9

9

20
22

16

18

39
45

10%

m

10%

24

20

48

12 8

12

26

20

49^

12%

12%

30

20

51V|

w»

12^

ESTIMATING GAS FOR ORCHARD WORK

8l

On low, damp grounds where fogs are frequent,
and especially for apple and pear trees, infested with
either the San Jose scale or codlin moth, or old seedling
orange trees infested with red, brown, or purple scale,
the following table should be used:

CHEMICALS FOR ORCHARDS ON DAMP GROUNDS OR WHERE
FREQUENT FOGS OCCUR

HIGHT

Diameter

Water

Sulphuric Add

Cyanide

Feet

Feet

Ounces

Ounces

Ounces

6

4

4

1

1

8

6

10

10

8

14

4

4 4

12

10

24

6

6

12

14

36

9

9

14

14

40

10

10

16

16

48

11

11

18

16

48

12

12

20

16

52

13

13

22

18

60

24

20

64

16

16

26

20

66

16#

30

20

70

17

17

In the tables given above the diameter is taken
through the foliage. The water and acid are estimated
in fluid ounces.

In Eastern orchards the amount of cyanide is some-
what greater than that used in California. Experience
has shown that 0.20 gramme of cyanide per cubic foot
of space enclosed gives most satisfactory results upon
scale-infested deciduous trees in the Hast.

In the preparation of the following table calcula-
tions are based on the hight and diameter of the tented
tree. First, the cubic contents of a cylinder was cal-
culated, the hight and diameter of which was the
hight and diameter of the tree, then the contents of a
sphere wrhose diameter was the hight of the tree was

82

FUMIGATION METHODS

estimated. By taking half the difference and adding
it to the contents of the cylinder the estimation was
found approximately correct.

CHEMICALS ESTIMATED FOR EASTERN ORCHARDS

HIGHT OF
TREE

Diameter

Cyanide

Acid

Water

Feet

Feet

Grammes

Ounces

Ounces

4

3

6.17

0.32

0.48

5

4

12.82

0.67

1.00

6

4

18.85

1.00

1.50

7

4

26.75

1.41

2.11

Ounces

7

5

.1.11

1.66

2.49

8

4

1.30

1.95

2.92

9

5

1.50

2.25

3.39

9

5

1.96

2.94

4.41

g

6

2.24

3.36

5.00

10

7

3.20

4.80

7.20

10

8

3.62

5.43

8.14

11

7

3.95

5.92

8.88

11

8

4.40

6.60

9.90

12

9

5.88

8.82

13.23

12

10

6.51

9.76

14.64

13

9

6.93

10.39

15.58

13

10

7.65

11.47

17.20

14

11

9.76

14.64

21.96

14

12

10.65

15.97

2345

15

11

13.28

19.42

29.88

15

12

14.24

21.36

32.04

16

14

16.34

24.51

36.76

16

15

17.53

26.27

39.43

17

14

18.39

27.57

41.35

17

15

19.36

29.40

44.23

18

15

22.06

33.09

49.63

19

16

26.10

39.15

58.72

20

16

29.00

43.50

65.25

A careful study of the tables made by various indi-
viduals for orchard work is interesting. The present
practice in California does not vary much in amount
of cyanide used per cubic foot from that originally
estimated by Coquillett and Morse. The results as
summed up by Woodworth are given in the following
table.

ESTIMATING GAS FOR ORCHARD WORK

COMPARATIVE VAIyUE OF CYANIDE PER CUBIC FOOT FOR
ORCHARD WORK

DATE

Name

Capacity per Ounce of Cyanide

1887

F. W. Morse
D. W. Coquillett
D. W. Coquillett
Alexander Craw
T. B. Johnson
C. W. Woodworth
W. G. Johnson

145 cu
95
165
352
242
300
80

bicfe

et

1888
1889
1891

1894

1896 . . .

1898

CHAPTER X

DAYLIGHT FUMIGATION AND COST OF
APPLICATION

N California experience has shown that the
citrus orchards can not be successfully fumi-
gated during the day. On the other hand,
in the East, in deciduous orchards, daylight
fumigation has been found most practicable. As a
rule, Eastern orchards are fumigated during the fall,
after growth is stopped and after the function of the
foliage has been performed. In such instances it mat-
ters little whether or not the foliage is injured by the
gas. In Fig. 44 will be seen a Japanese plum tree, one
of a block of 5,000, fumigated in October with the 0.20
gramme formula. While these trees were fumigated
in daylight, the foliage in this particular instance was
practically uninjured. In some cases where the fumi-
gators were left over the trees longer than thirty min-
utes, the foliage was somewhat seered, but no injury
resulted to the trees. By referring to Chapter III. it
will be seen that the physiological effect of this gas
varies with certain kinds of trees, and is influenced by
weather conditions and time of day.

In the Eastern orchards the gas is best applied
during the daytime late in the fall or early spring, as
will best suit conditions and circumstances. In Fig.
84

DAYLIGHT FUMIGATION, COST OF APPLICATION 85

24 the apparatus was used in the plum orchard during
the month of March . The buds had j ust begun to swell ,
but no injury was noted, while the scale was destroyed.

FIG. 44 JAPANESE PLUM TREE IN FULL FOLIAGE

FUMIGATED IN OCTOBER

In the fumigation of nursery stock, especially in the
house, it makes little or no difference at what time of
the day the trees are fumigated.

Expert Opinion. — There has been considerable dis-

86 FUMIGATION METHODS

•

cussion regarding daylight fumigation in California.
The following interesting letter from R. P. Cundiff , an
expert on this subject and Chairman of the Riverside
County Board of Horticultural Commissioners, is of
timely interest: "What I say upon this subject is
mainly from a local standpoint. While I seriously
doubt the practicability of daylight fumigation in any
locality of southern California, I am not prepared to
maintain that in some localities, during certain
climatic conditions, and for some varieties of scale, it
might not be done with reasonable safety. However,
I know of no practical fumigator who has ever advo-
cated it. I am under the impression that those who
are giving such learned opinions on this subject are
possessed of more of a theoretical than practical knowl-
edge of fumigation by hydrocyanic acid gas.

4 ' In Riverside County we have found it necessary
to fumigate but little for black scale, for it has never
assumed the proportions of a serious pest, as in some
of the coast counties. Our fumigation has been almost
entirely for red scale. It is a well-known fact among
fumigators that it requires almost double the quantity
of cyanide to kill red scale that it does for black or
brown scale. This must be taken into account when
we come to discuss the proposition of daylight fumiga-
tion. Another consideration is the difference in tem-
perature. Riverside, being an interior county, is sub-
jected to several degrees more heat than localities near
the coast. Another point that should be considered is
the season of the year when the work is performed.
Fumigation for black scale, to be in any degree effect-
ive, must be done during the fall and winter months.

DAYLIGHT FUMIGATION, COST OF APPLICATION 87

Especially is this true of I^os Angeles, Orange, and
San Diego counties, where ordinarily an orchard is
fumigated but once a year. In any of these counties
from October until March is considered the best time.
During this period the scale is young and will yield
quite readily to treatment by fumigation.

' ' As fumigation for red scale seems to be equally
effective at all times of the year, in order to incur the
least damage to the grower, in the way of knocking off
fruit, etc., also to avoid rainy weather and north
winds, we have made a practice in Riverside County of
doing the greater part of the fumigation between the
months of May and December. This period embraces
our warmest weather. In this connection I wish to
refer to a matter that has evidently escaped the atten-
tion of the advocates of daylight fumigation. During
our summer months we have periods, sometimes ex-
tending over many days, when the mercury will range
in the nineties. With a temperature of from 90 to 95
degrees we are quite sure that by enclosing a tree
under an air-tight tent for the time required for fumi-
gation, which is from 40 to 45 minutes, the tempera-
ture under the tent would be increased from 25 to 30
degrees. Add to this the increased heat caused by
generating the chemicals, which would be perhaps
10 degrees more, and the resulting temperature would
very likely do harm. It is well known that a citrus
tree will not stand a temperature of 135 degrees for
any length of time without serious results. We know
from actual observation that the action of sunlight upon
hydrocyanic acid gas has a scalding or burning effect
upon foliage. Practically all of the damage ever done

88 FUMIGATION METHODS

in Riverside County from fumigation with cyanide has
been caused by an occasional mistake of the foreman of
fumigation in either beginning his work too early in
the evening or continuing it too late in the morning.
This has, however, seldom occurred, as few fumiga-
tors who understand their business will risk their
reputations by taking such chances. I recall to mind
a suit brought against the county some years ago for
alleged damages by one of our growers. This, I un-
understand, was a case of daylight fumigation.

' ' I quite agree with the advocates of daylight
fumigation that there would be some advantages
gained by doing the work in the daytime instead of
night. There would be a small saving in chemicals,
but not nearly so much as claimed by some. It would
be also easier to locate trees and move the apparatus
from place to place. On the other hand, there are
some advantages in doing the work at night. The
handling of a fumigating outfit, especially where large
tents are required, is very laborious. Men could do
more work with less fatigue on account of the cooler
temperature. This would be especially true in River-
side County, where the greater part of the fumigation
is done during the warm months. I am under the
impression that it would be difficult to get men to work
during the very warm weather in the daytime, as the
reflection of the sunlight on the tents would increase
the heat to such an extent that they would prefer
other work at less wages. As was intimated at the
beginning, it is probable that in some of the coast
counties, in fumigating for black scale, where the
amount of cyanide is much less than for red scale,

DAYLIGHT FUMIGATION, COST OF APPLICATION 89

fumigating could be done on cool, cloudy days with
comparative safety. But in Riverside County, where
the fumigation is almost entirely for red scale, where a
much greater amount of cyanide is required, and
where it is necessary to do the work during the warm
weather, it would certainly be a very unsafe thing to

FIG. 45 — CHARGING A CALIFORNIA HOO.P TENT

do. And the orchardist who attempts it will probably
be reminded of this fact by having his trees damaged. ' '
The cost of or chard fumigation depends upon the loca-
tion of the orchard, the kind and size of the tree, and,
to a certain extent, upon the prevailing weather condi-
tions under which the work is done. The actual cost of
fumigation is not necessarily very great after the out-
fit is once secured. With a small number of Emory
fumigators, or sheet tents, most fruit growers can apply

90 FUMIGATION METHODS

the gas method withouj: difficulty if the rules given
herewith are carefully followed.

Ivarge outfits are so expensive it is desirable in
many cases for the state, county, or local society to
own the tents and other equipment. In California
especially, where it is necessary to operate at night,
these outfits are practically controlled by county and
local organizations. The number of persons necessary
to operate a system of fumigators depends somewhat
on the size of the trees and the number and kind of
tents. One or two men introduce the chemicals,
others look after the vessels, measure the acid and
water, while others manipulate the tents. As soon as
the tent is in place, the fumigator enters it, introduces
the chemicals, withdraws quickly, closes the tent, and
proceeds to the next tree. In many cases the assistant
raises the edge of the tent, while the fumigator enters
and drops it as soon as he comes out. The wagon
containing the chemicals is then drawn to the next
tree. The generator beneath the tree just fumigated
is removed, and the contents poured on the ground near
the trunk of the tree. The acid and water are meas-
ured, carried to the next tent, and introduced, as shown
in Fig. 45. Various appliances are used for carrying
and handling the chemicals in an orchard in the east.
A wheelbarrow or small hand-cart has been found very
useful, as shown in Fig. 22. In other cases a small,
table-like tray is used to carry the apparatus, as seen
in Fig. 38.

The location of an orchard and its freedom from
dampness and fog must be considered. The ground,
trees, and the leaves should be dry when fumigated.

DAYLIGHT FUMIGATION, COST OF APPLICATION 91

If perceptibly damp the gas is more liable to burn the
foliage. After irrigation, where it is practical, the
ground should be allowed to become quite dry before
the fumigation operations begin. When trees are wet
with dew or a slight rain, care should be taken to see
that they are fairly dry before being tented. In some

FIG. 46 — WAGON FOR CARRYING CHEMICALS IN ORCHARD

instances fumigation in Eastern orchards can not be
commenced before nine or ten o'clock in the morning
or until the trees are dry.

Care of tents. — When a large fumigating outfit is in
operation each tent should be thoroughly inspected
daily. In most cases this can be done to best advantage
wrhen the tent is over the tree. The inspector should go
under the tent and carefully examine it. If there are

92 FUMIGATION METHODS

any holes in it they *can be easily detected. The
places should be marked and patched at once. Some-
times a patch is glued on, but it is preferable, in most
cases, to sew them on in the usual manner. For tem-
porary purposes a small stone, nut, or even dirt, tied in
the rupture will answer until it can be patched.

CHAPTER XI
EQUIPMENT FOR FUMIGATING NURSERY STOCK

T""!HK enclosure necessary for fumigating purposes
. in nurseries varies considerably. In some
cases boxes will accommodate the grower,
but the building is usually constructed in
accordance with the number of trees grown or handled.
Some nurserymen have found it necessary to construct
a house large enough to hold 12,000 to 15,000 first-
class trees at one time. Some firms handling a million
or more trees annually have rooms large enough to
admit a wagon-load of trees at one time, examples of
which are given in Figs. 52 and 64.

A good tent, such as is seen in Fig. 12, can be used
in cases of emergency, but it is not advisable to de-
pend upon a tent altogether. Many nurserymen have
found a small box tent, similar to the one shown in
Fig. 32, very useful. Still others have used a sheet
tent over a wagon-load of trees to good advantage.
There are some objections to a tent or box covered
with canvas ; in the first place, by constant use it is
liable to be torn, and, secondly (and most important),
the cubic capacity of space enclosed under a sheet tent
will vary with the amount of stock fumigated. Herein
lies the greatest source of error, inasmuch as the
chemicals must be weighed every time for each indi-
vidual lot of trees treated. Where the box or Emory

93

94 FUMIGATION METHODS

fumi gator is employed, however, this difficulty is over-
come, as the cubic content is constant and the amount
of chemicals used does not vary. The danger of error
is eliminated when a box or house is used. It matters

FIG. 47 — BOX USED BY SOME NURSERYMEN IN THE SOUTH
(AFTER SHERMAN)

not whether one or several thousand trees are placed
in the enclosure, the amount of gas generated must re-
main constant.

Small boxes. — Many nurserymen find small boxes
very useful. Fig. 47 is a box used in North Carolina.
The details for construction are given by Prof. Frank-

EQUIPMENT FOR FUMIGATING NURSERY STOCK 95

lin Sherman, State Entomologist of North Carolina.
Build box of plain matched three-quarter inch ceiling,
making walls, top, and bottom double, with two thick-
nesses of rosin-sized or tarred paper between. Rein-
force the corners with 1^x3 inch stuff, and stiffen
the corners with 2x3 inch battens.

Make the uprights of 2 x 6 inch stuff, and the two
keying beams of 2 x 8 inch stuff, ceiling to be in con-

FIG. 48 — TYPE OF BOX USED BY SOME CANADIAN NURSERYMEN
(AFTER LOCHHEAD)

tinuous pieces, and all joints to be wiped with white
lead and driven up close. Give the box two good
coats of lead and oil paint, both inside and out, and
repeat each year. The size of the box is ten feet long,
forty inches high, thirty-six inches wide. Cover the
upper edge of the box with heavy felt, glued down
tight, so as to make a tight cushion- joint when top is
down. Glue a two-inch wide strip of felt around the
small opening near the bottom of the box. When cover
is put on, the 2x8 inch timbers, eleven feet long, are

96

FUMIGATION METHODS

slipped through the mortices in the uprights, and are
keyed down to force the*top down tight. Nine inches
from the bottom of the box put in a false slat bottom,
made in sections, so it can be removed to clean out
dirt from bottom of box. The chemicals are placed in
a little shallow dish and put into the box through the
little door, A, which has a shutter keyed up tight to
side of box.

Another handy box, devised by a Canadian nurs-
eryman, is made of double matched sheathing with

FIG. 49 — THE OPEN BOX USED IN SOME MARYLAND NURSERIES
(ORIGINAL)

tarred paper between. The top is held tightly against
the felt padding by driving the wooden hooks from an
upright into a slanting position. The hooks are made
of hard wood pieces 1x3 inches, cut so as to hook over
the edge of the lid and under the long side strip. The
rack in the bottom of the box keeps the trees away
from the chemicals and insures a thorough penetration
of the gas. This box is shown in Fig. 48.

A plain box, 6x3 x 2^ feet is very satisfac-
tory for small orders. It should be made of two
thicknesses of common flooring. The construction is

EQUIPMENT FOR FUMIGATING NURSERY STOCK 97

shown in Figs. 49 and 50. It is a simple, plain, open
box, and when filled with young trees, kept in place
by a couple of slats, a, it is turned bottom upward
on the ground and a little loose earth is stamped about
the edges. The chemicals can be easily introduced by
tilting the box slightly, as shown in Fig. 50. It is
less troublesome than boxes having lids, and can be
used to very good advantage in most cases where
small numbers of trees are grown.

A fumigatorium is a house or room constructed or

FIG. 5O— OPEN BOX REVERSED READY FOR CHEMICALS
(ORIGINAL)

adapted for the fumigation of nursery stock or other
material with hydrocyanic acid or other gases. It is
not necessary in all instances to construct a separate
building for this purpose. In most cases where a nurs-
ery has been established some years a shed or one
corner of a building, packing-house, or other enclosure,
can be adapted so as to make a satisfactory room or
house for fumigating purposes. Cover the frame
inside with cheap boards; then put on three-ply cyclone
or rawhide building paper, and finally the flooring.
In every case have a good smooth surface on which to

EQUIPMENT FOR FUMIGATING NURSERY STOCK 99

secure the paper. The flooring can be joined very
easily and will be tight. The ceiling and floor
should be constructed in the same manner. In some
cases a good solid clay floor will answer. Care should
be taken to see that the house is absolutely tight at the

FIG. 52 — ROOM WHERE TREES ARE FUMIGATED BY THE
WAGON-LOAD

ground surface A ceiling six to seven feet in hight
is most desirable and economical.

One of the largest houses in the country in which
nursery stock is fumigated is shown in Fig. 51. It is
32 x 1 6 x 8 feet with a roof -pitch of two feet, and is
divided into two large rooms about 15 x 14x7 feet
and two smaller rooms 4x5x7 feet. The flues lead-
ing out at the top of the roof are so arranged they will

100

FUMIGATION METHODS

ventilate either room by jemoving a slide. In addition
to these roof- flues there are also two small doors, 3 x
2^ feet, one for each large room, on the opposite side
of the building, which, when opened, insures quick
ventilation.

In the construction of this house, first a good

FIG. 53 — DOUBLE ROOMS BUILT IN END OF PACKING-SHED

strong frame was built and covered outside with one
and one-quarter inch twelve-inch Virginia pine boards,
^ x 4 inch battens. The interior, including the floor,
was lined with two-ply cyclone paper, over which
four- inch flooring was laid. The roof was covered
with heavy roofing paper, tarred and graveled. The
doors are 6% x 3/4 feet, made double, refrigerating

EQUIPMENT FOR FUMIGATING NURSERY STOCK IOI

style, and hung with three heavy strap-iron hinges.
There should be a good strong bolt at top and bottom,
and a lock in the middle of the door.

Another form, and very convenient house for firms
handling a million or more trees, is shown in Fig. 52.
It is built in one end of the packing-shed, and is 16 x

i

FIG. 54 — SINGLE ROOM USED IN WINTER FOR GRAFTING

13 x 9^ feet. There is another room the same size on
the opposite side of the building. These houses were
constructed so as to admit a wagon-load of trees at one
time. While a load is being fumigated in one side,
the other is being removed and everything is in readi-
ness for another charge. These rooms are really too
large, and it requires a great deal of cyanide to fumi-

EQUIPMENT FOR FUMIGATING NURSERY STOCK 103

gate space not occupied by trees. For example, the
space occupied by the wagon must be considered.
The construction of this house is the same as the pre-
ceding, except that the roof is of corrugated iron and
a clay floor.

Another type of hou.se is shown in Fig. 53. Here

F.IG. 56 — VERY HANDY AND CHEAP HOUSE FOR SMALL NURSERY

the two rooms are built in the end of the large packing-
shed. There are two doors, same size as those open-
ing outside, leading into the packing-shed. The
rooms are filled with trees, and when fumigated and
ventilated, by means of a large flue leading out the
top of the roof, they are passed into the packing-shed.

104

FUMIGATION METHODS

This is one of the handiest and best-constru<5led houses
in Maryland.

A single room, suitable for a quarter to a half a
million trees, is shown at Fig. 54. This house is con-
structed with sliding windows in addition to the small
doors. The flue is so arranged that it can be used as
a chimney, if necessary, in winter. In fact, this is
called the " handy house." In cold weather it is used
for grafting. The room is i3x n x8 feet.

Another single room of smaller size is shown in

FIG. 57 — OUTLINE OF MODEL FUMIGATING HOUSE. (ORIGINAL)

FIG. 58 — PLAN OF SLAT FLOOR. (ORIGINAL)

Fig. 55. It is a very handy and neatly constructed
house. Itisi2xi4xy feet. It is sided up with
first-class tongue and grooved flooring, instead of or-
dinary boards, and has a corrugated iron roof. There
is a small door in the opposite end, wdth a sliding
window. This house accommodates a firm handling
a quarter of a million trees annually.

A very handy and economical house is shown in

EQUIPMENT FOR FUMIGATING NURSERY STOCK 105

Fig. 56. It consists of one large room, 10 x 8 x 7
feet and two smaller rooms, each 4x4x7 feet. Only
one of the smaller rooms is lined. The other one is
used as a storeroom, in which all chemicals and other
materials are kept.

One of the most convenient houses used has a ground
plan of 12 x 1 6 feet. It is divided into three sections, as

FIG. 59 — GENERAL PLAN OF FLOOR. (ORIGINAL)

follows : one large room 12 x 12, and a small room 4 x
8, with a storeroom 4x4 feet. The floor plan and
general outline of this building are shown in Figs. 57,
58, and 59. It has a double floor with paper between,
and a space of one and one-half feet, as shown in the
diagram, d d, above which there is a slat floor, on a
level with the bottom of the door, as shown at a and
b. In the storeroom, e, the floor is solid. In the
construction of this building the slats should be made
in sections, so they can be removed. It will be found
necessary to clean the lower part of the house from

FIG. 60 — WHERE TREES ARE FUMIGATED BY THE MILLION

FIG. 6l — A WELL-BUILT SINGLE-ROOM HOUSE FOR SMALL
NURSERY

EQUIPMENT FOR FUMIGATING NURSERY STOCK 1 07

time to time, as more or less dirt will rattle through
the slats upon the floor. The slats are used so that
the gas can be generated underneath the nursery stock,
thereby obtaining a more general diffusion.

The jar containing the chemicals can be placed
under the slats through the small doors at the base,

FIG. 62 — A COMPLETE FUMIGATING HOUSE IN UTAH

d d, and very often it is advisable in a large room to
have two doors of this character, so that the chemicals
can be divided and the gas generated on opposite
sides. Good results are obtained where this plan is
followed. The small doors used for ventilation pur-
poses, c c, can vary in size to meet the conditions.
The door entering the storeroom need not be double,
and 3x6 feet is a convenient size. A good solid

jZoor *±Y***&;jt+*^

FIG. 63 — SECTIONAL VIEW OF A MODEL UTAH HOUSE
(AFTER MOORE)

EQUIPMENT FOR FUMIGATING NURSERY STOCK IOQ

dirt floor will answer, provided the room is made per-
fectly tight at the bottom.

Two other model houses are shown in Figs. 60 and
61. The former is for a large nursery, while the latter
is used for a smaller concern, handling half a million

FIG. 64 — DOUBLE HOUSE IN CANADA FOR FUMIGATING TREES
ON A WAGON

trees or less. The latter is used for a storehouse when
not in use for fumigation.

One of the newest fumigating houses in the north-
west is shown in Fig. 62. It is 10 x 14 feet. The
details of construction are about the same as those
already given. The ventilator and method of oper-
ating it is shown in Fig. 63. This house, complete,
cost about $70.

Of the many fumigating houses in use in Canada

IIO FUMIGATION METHODS

those shown in Figs. 64 and 65 will serve as examples.
Figure 64 is a view of a double house. It has two
separate compartments. While a load of trees is being
fumigated in one compartment, ventilation is taking
place in the other. It has two thicknesses of lumber,
one matched, tongue and grooved, the other either the

FIG. 65 — CANADIAN FUMIGATING HOUSE AT THE ONTARIO
AGRICULTURAL COLLEGE

same or cover-siding well-matched, and two thicknesses
of paper between. The doors are the same and padded
all around.

Figure 65 shows the fumigation house at the Agri-
cultural College at Guelph, Canada. It is substan-
tially built, dressed lumber being used in its construc-
tion. Its size is 10x8x7^ feet. It contains 600
cubic feet. The frame, of 2 x 4 inch scantling, has two

EQUIPMENT FOR FUMIGATING NURSERY STOCK III

thicknesses of lumber, both matched, tongue and
grooved, and firmly nailed on the outside, with a
thickness of tarred paper between. Besides, the seams
on the outside are covered with strips. The doors are
of the refrigerator style, and the casements are padded
with soft felting. Large wooden buttons are placed
on the outside, around the edge of the door, to force it
closely into the padded casement. The roof has a
thickness of matched boards, then a thickness of
tarred paper, then shingles. The cost of the complete
building was a trifle over $20.

CHAPTER XII

CONSTRUCTION OF VENTILATORS AND FLOORS

O""YNK of the Canadian houses has a unique venti-
I lator. Just before the gas is generated the
hinged trap is pulled up tightly against
the felt, and the rope fastened to a cleat on
the side of the house, as shown in Fig. 66. Before the

FIG. 66 — METHOD OF VENTILATING A FUMIGATING HOUSE
(AFTER LOCHHEAD)

door is opened the rope is loosened, and the weight
brings down the trap and allows the gas to escape. A
ventilator of this kind having the trap opening into
the inside is protected from the weather, and is not
subject to the troublesome warping of exposed cap
ventilators.

An Ohio arrangement. — In his practical work in

112

CONSTRUCTION OF VENTILATORS AND FLOORS 113

Ohio, Prof. F. M. Webster has fo^nd slats raised
eight inches or a foot from the ground preferable to
the ground floor. Where it is intended to drive
wagons into the house the ground floor will answer
all purposes. With a slat floor the gas is generated
beneath, and spreads almost instantly throughout the
space between the ground and the slats, passes up-

FIG. 67 — DIAGRAM OF GENERATOR AND SECTIONAL VIEW
OF FUMIGATORIUM. (AFTER WEBSTER)

ward through the trees, and promptly reaches every
part of the apartment.

The generator, shown in Fig. 67, consists of an
earthen jar of the requisite capacity, a, fixed to the
end of a plank, b, and just in front and between two
posts, cct through which passes a roller, dt and to
this last is fixed a pan, £, with back and sides but
no front, one end of the roller projecting beyond the
post with a small iron bar or heavy wire, /, passing
through it, and being fixed and bent at either end, the
whole having much the appearance of a windlass with
pan, e, added. The sulphuric acid and water are

FUMIGATION METHODS

placed in the jar, and the potassium cyanide in pan
above, and the plank pushed down a slight incline, as
seen in the figure, over which a cleat, g, is fastened,
which catches the wire or rod,/, and thus dumps the
pan, e, throwing the contents into the jar, at there-
by completing the mixture and generating the gas;
and, as a drop-door closes as soon as the plank is

FIG. 68 — LOWER PORTION OF FUMIGATORIUM, SHOWING SLAT

FLOOR, IN CROSS-SECTION, AND GENERATING APPARATUS

(AFTER SANDERSON)

pushed down the incline, there is no chance of the
operator breathing the fumes. The arrangement is
simple, and any one at all handy with tools can easily
construct the whole apparatus.

The Delaware method. — As a result of the splendid
work of Professors Sanderson and Penny, of the
Delaware Experiment Station, many obscure points
about the diffusion of the gas have been cleared
up. Their experiments point to the utility of a slat
floor. As a modification of the ordinary slat floor, to

CONSTRUCTION OF VENTILATORS AND FLOORS 115

secure better diffusion, an arrangement of the floor
and generator, as shown in Fig. 68, is recommended.
This provides for a slat floor, underneath which run
smooth wooden tubes, three inches in diameter, along
the diagonals of the room and opening into a hood
placed at the center covering the generator. These
tubes, extending from the center, two-thirds of the

FIG. 69 — GENERATOR AND DETAILS OF HANDLING IT
(AFTER SANDERSON)

distance to the corner, are open at the ends, and one-
third from the center, affording eight openings for the
escape of the gas.

The bag of cyanide is placed on a shelf and the
generator in the box, A, at the end of the sliding
board, B. This board is pushed down the incline,
C, and when under the board the outer end is pushed
down and held in place by a sliding door. The
shelf upon which the cyanide is placed rests on a
pivot, as shown in Fig. 69 at D. Projecting upward
from it is a rod, E, forming a trap. When the box is

Il6 FUMIGATION METHODS

thrown up beneath the hood the shelf is tipped and
the cyanide dumped info the generator. This device
is simple and cheap.

A good Western idea. — A Western firm has a
novel and practical way of making an open floor and
generating the gas underneath. They say : ' ' Our
fumigating house is 15x20x10 feet. The walls are
double, of one-inch plank, the first course being put
on lengthways of building, then common building
paper, tarred after being put on. The second course
of plank is put on up and down. This course is on
the outside ; roof made the same way ; doors simi-
larly made, are double, and take up one end of the
building. After the building was completed, we
banked up around the bottom about a foot with dirt ;
then we excavated about a foot and a half deep, one
foot from the bottom of the walls. For instance, if
the room was 10x20 feet, the excavation would be
9x19 feet, surface measure. Over this excavation is
laid three 2x4 inch joists, just enough to hold the
stock which is put in for fumigating. Across these
joists lay two or three 1 2-inch planks, loose. This
completes the house.

* 'An opening or flume is made under the wall about
one foot deep and eighteen inches wide. The end
extending into the inside of the building is open, and
extends just far enough to let the gas into the exca-
vation under the trees. The outer end extends out
far enough to give the operator ample room to insert
the vessel containing the chemicals. The outer aper-
ture is covered with a trap-door. The vessel with the
acid and water is set in the flume, trap- door open, and

CONSTRUCTION OF VENTILATORS AND FLOORS 117

the cyanide dropped in. The trap-door is closed
quickly and is covered immediately with a piece of
cloth (blanket is best), and dirt hurriedly thrown
over the whole business. This prevents any of the
gas from escaping, and makes the building absolutely
air-tight, which is necessary. The gas fills the exca-
vation and rises through the loose floor, permeating
through the trees, filling the entire inside of the
house. In our building we treat about five thousand
trees at a time. For fall deliveries we treat the stock
as it comes from the field to the packing-ground. For
spring delivery we treat them as we take them from
the healing grounds to the packing-grounds. The
cost of our building did not exceed $50 complete. ' '

CHAPTER XIII
PRACTICAL HINTS TO NURSERYMEN

T!HK amounts of chemicals necessary for a room
i are estimated in terms of cyanide per cubic
foot of space enclosed. For example, let us
suppose a room contains 564 cubic feet. We
use 0.25 (twenty-five hundredths) gramme of cyanide
for each cubic foot. We therefore multiply 564 by
0.25. Thus, 564 X 0.25 = 141.00 grammes of cyanide.
To reduce this to ounces we divided 141.00 by 28.35,
as there are 28.35 grammes in an ounce. Thus,
141.00 -=- 28.35 = 5 ounces (a fraction less), the amount
of cyanide needed for the house. The other chemicals
are easily determined, as a half more acid, liquid meas-
ure, than cyanide, and a half more water than acid
are used. Thus, the room needs 5 ounces cyanide (by
weight), 7^ ounces acid (liquid measure), and n^
ounces (liquid measure) of water.

As a rule, we discard any fraction less than a half.
In this case, therefore, we would use 5 ounces of
cyanide, 7^2 ounces of acid, and n ounces of water.
The cost of chemicals to fumigate this room, full of
trees, would be about 1 1 cents. The amount of cya-
nide needed for any room can be determined in the
same manner. First, see to it that the cubic contents
of the enclosure has been accurately computed, then
118

PRACTICAL HINTS TO NURSERYMEN 119

multiply by 0.25 (twenty-five hundredths) and divide
by 28.35, as indicated above, and you will obtain the
correct amount in ounces. Always bear in mind that
fumigation will admit of no guesswork, as success
depends on accuracy.

Low-grade stock, as indicated in Chapter III. , should
not be fumigated with the 0.25 gramme formula. The
o.i 6 or o.i 8 formula should be used for June budded
peach or plum, low grade peach and plum, known
as whips, and for scions, buds, grafts, etc. In using
this formula, the cubic contents of an enclosure should
be multiplied by o. 16 or o. 18, as the case may be, and
reduced as above to ounces.

Cost of nursery stock fumigation. — It is difficult to
ascertain the exact cost for fumigating young trees
per thousand. The conditions under which the trees
are grown and handled in most States varies consider-
ably. In most cases, nurserymen who have had much
experience along this line have found that the ordi-
nary first-class grade of fruit trees can be fumigated at
a cost not to exceed twenty-five cents per thousand
trees. This amount includes the chemicals and extra
labor in handling. However, the cost of the fumiga-
ting house or box is not taken into consideration. In
many cases where a room can be filled with trees the
cost of fumigation can be reduced from ten to fifteen
cents per thousand trees, depending upon the grade
and kind. It is often necessary to fumigate a small
bundle of trees in a large room or enclosure. In such
a case, the quantity of chemicals necessary to fill the

120 FUMIGATION METHODS

room is the same as if Jhe entire enclosure was filled ;
therefore, the cost would be somewhat increased.

Small room a necessity. — Whatever may be the
size of the nursery, a small room, say 4x5x7 feet, is
a necessity. Very often a small order or a few trees
to complete a big order are needed quickly. It would
be poor economy to use eighteen ounces of cyanide,
costing about forty cents, to fumigate a handful of
trees in a large room, when one ounce, costing less than
two and one-half cents, in a small room would answer
the same purpose. It is not desirable, in most cases,
to mix up small orders with car-load lots, and in most
nurseries a small room will be found in almost con-
stant use. The kind, shape, size, and location of the
fumigating house rests entirely with the individual,
and he must be the judge as to what is best suited for
his purposes. One thing must be remembered at all
times, whatever may be constructed, and that is, it
must be gas-proof.

Preparation of trees. — The house having been con-
structed, the next step is the proper preparation of the
trees for treatment. In the first place, care should be
taken that the trees are thoroughly matured and dor-
mant before they are dug and passed into the fumi-
gating house. Nurserymen should heed carefully the
cautions cited in Chapter III. Well-matured nursery
stock should be dug in the customary way, tied in
loose bundles, brought to the fumigatorium, and piled
loosely, not packed, upon the floor, with the roots
toward the walls and tops overlapping. The trees
should be as dry as possible. They may be damp or

PRACTICAL HINTS TO NURSERYMEN 121

moist, but should not be drenching wet. Where only
a few trees are fumigated, they are usually stood on
the floor in bunches. When the desired number has
been placed in the room, and the ventilators have been
closed, they are ready for the gas. The chemicals are
then prepared and placed, after which the doors are
closed, and left the desired length of time. A half-
hour is the minimum limit, but thoroughly matured
dormant trees are not injured in the least if left an
hour. The chemicals should be prepared and used
strictly in accordance with the directions given in
Chapter II.

Other materials needed. — A pickle jar or china dish
holding from two to four quarts is best adapted for
holding chemicals for the generation of the gas in
ordinary houses. Sometimes a larger vessel, such as a
snuff- jar, is needed. A liberal supply of small manila-
paper bags holding a pound or more are necessary.
Where the amount of cyanide needed is known, it can
be weighed, placed in manila bags, and kept in an
air-tight can or other enclosure ready for use. Care
should be taken not to weigh too much cyanide at a
time, as the bags become saturated with moisture if
long exposed to the air. It is best to weigh the cyanide
at night or early in the morning, or even during the
noon hour, rather than have it standing around for
several days. A glass beaker, holding from a pint to
a quart, with a graduated scale on the side in ounces,
will be required for the acid and water. A supply of
acid should be kept in a carboy or other vessel. It
should be drawn in an ordinary glass, china, or agate
pitcher, as needed. For immediate use, a supply of

122 FUMIGATION METHODS

water, together with a cup or glass for dipping, should
be kept close at hand.

Cellars and cars. — It is not desirable to attempt to
fumigate trees after they are packed in cellars or cars.
In some cases serious injury has been done when trees
were fumigated in freight-cars after being packed.
As a rule, the roots are so closely packed with moss
and other materials when put in cars it is difficult
for the gas to get to them. It is practically im-
possible to properly ventilate the car afterward, and
more or less gas is left. The only proper place to
treat trees is in the fumigatorium.

Canvas over wagon. — An enterprising nursery firm
in Utah uses a canvas sheet over a wagon loaded with
trees, in addition to the use of a house. They give the
following description of house and method of handling
tent: " For a number of years we used a small room
about 12x12 feet. Finding this too slow a process,
we put up a building 22 x 56 and 9 feet high. The
roof and entire building is made with two thicknesses
of i x 12 feet boards, with building paper between,
which makes it very tight. As this was rather large
for ordinary use, we made a partition, making the
smaller room 22 x 20. This latter room we use mostly
when we store our stock inside to be treated.

<l We think, however, by far the better and more
economical method is to do the fumigating on the wagon
at the time stock is dug and hauled in. This is done
by using a canvas sufficiently large to cover the entire
load, with a few feet of margin, which should be spread
on the ground and weighted down to keep the fumes

PRACTICAL HINTS TO NURSERYMEN 123

from escaping. In order to lower wagon, trenches
should be made to allow wheels to drop down. Our
canvas is 32 x 38 feet. This is a large sheet and un-
wieldly to handle unless parties know how it should
be done. Our method is to place the sheet behind the
wagon, doubling the front end back over the other.
To the corners of the top 'canvas fasten poles long
enough to clear the load. Fasten lines at ends of
poles, and when ready to raise have men pull the
ropes. The air will be of great assistance, and if
quickly done the canvas will sail over without friction.
Our experience has been that hydrocyanic acid gas
properly applied is certain death to all insect life. ' *

Points to remember. — i. Never let a tree go out of
the nursery unless it has been fumigated.

2. Never fumigate a tree on which there is known
to be a San Jose" scale. The furnace, and not the
fumigating house, is the place for such trees. A dead
scale on the tree is just as demoralizing to the nursery
business as a live one if seen by the buyer.

3. Never use the gas stronger than 0.25 gramme
cyanide per cubic foot on any kind of nursery stock.

4. Never leave the trees exposed to the gas longer
than an hour. Thirty to forty-five minutes is suffi-
cient.

5. Never fumigate trees, especially peach, a second
time.

6. Never fumigate trees in a car, box, or cellar after
they are packed.

7. Never fumigate trees when they are drenching
wet. They may be moist, even quite damp.

124 FUMIGATION METHODS

8. Never puddle the roots of trees before they are
fumigated.

9. Never fumigate cedars and evergreen trees,
unless there is some special reason for it.

10. Never fumigate trees until the wood is well
matured and the buds are thoroughly dormant.

1 1 . Never fumigate trees after the buds have begun
to open in the spring.

12. Never fumigate June buds and peach under
three feet with gas stronger than o. 18 gramme cyanide
per cubic foot. Better use o. 16 gramme.

13. Never fumigate buds, grafts, or scions with gas
stronger than o. 16 gramme.

14. Never leave the cyanide can where children
can reach it.

15. Never let the cyanide can be without a con-
spicuous label, " Poison."

1 6. Never leave the cyanide exposed to air. It
will absorb moisture and be ruined.

17. Never take a bag of cyanide out of a can
unless you are all ready to use it.

1 8. Never leave the door of the fumigating room
open a moment after the cyanide has been dropped in
the jar.

19. Never allow a person to go near or open the
door when fumigating trees or anything else.

20. Never allow anybody to enter a room under
ten to fifteen minutes after the door and ventilators
are open.

21. Never empty residue of jar where children
would play in it.

22. Never allow residue to remain long in the jar.

PRACTICAL HINTS TO NURSERYMEN 125

22. Never put a new charge in a jar containing the
old residue.

24. Never put sulphuric acid in tin or iron vessels ;
it will eat them up. Always use glass, earthenware,
agate, or wooden vessels.

25. Never lose an opportunity to caution persons
about the danger attending the inhalation of this gas.

CHAPTER XIV
GREENHOUSE AND COLD FRAME FUMIGATION

T""|HE greenhouse problem in reference to insects
has been one of considerable importance.
Early in 1894 Dr- Albert F. Woods, assisted
by Mr. Dorsett, as noted in Chapter III.,
began a series of experiments under glass with this
gas. They found that plants were less injured by a
short exposure to a relatively large amount of gas
than they were by a long exposure of a relatively
small amount. It was also shown that the stronger
dose a short time was most destructive to the insects
affecting the plants. In these experiments they
showed that different species and varieties of plants
varied remarkably in their power to withstand the gas,
depending upon the open or closed condition of the
breathing pores of the leaf, the cell contents, and tem-
perature of the inclosure. The plants fumigated were
ferns, coleus, double English violets, single violets,
roses, carnations,, grapes, tomatoes, and cucumbers.

The amount of cyanide used per cubic foot of space
inclosed varied from 0.075 gramme to 0.15 gramme.
For instance, ferns, infested with a scale insect, sim-
ilar to the scurfy scale on apple, were fumigated at
night with 0.075 gramme 98 per cent, cyanide for
twenty minutes without injuring the most delicate
fronds, at the same time destroying all the insects. In
case of coleus, infested with mealy bug, in a very

126

GREENHOUSE AND COLD FRAME FUMIGATION 127

large house (15,587 cubic feet), one-tenth (o. 10)
gramme cyanide was used. In case of the double
English violets, infested with plant-lice, slugs, milli-
pedes, leaf-eating larvae, cutworms, red spiders, etc.,
fifteen hundredths (0.15) gramme was used, and ex-
posed twenty minutes. All the insects were destroyed,
excepting a few red spiders, and even these were kept
down by frequent fumigation.

EffeEls on foliage. — The foliage of single violets,
like California, Princess of Wales, and the like, is some-
times slightly injured with the stronger dose of 0.15;
a weaker amount, one-tenth (o. 10) gramme should be
used for these single varieties. Roses, especially the
younger growths, are very sensitive, and slight injury
has been noticed even where the smallest dose (0.075
gramme) was used. Carnations will stand one- tenth
(o. 10) gramme for fifteen minutes; but more careful
experiments are needed before the gas is generally
recommended for either carnations or chrysanthe-
mums.

Grapes, under glass, in New Zealand, have been
fumigated at the rate of nine-hundredths (0.09)
gramme over night, infested with mealy bugs, with
good results. It has also been used successfully by
Dr. J. Fisher on tomatoes infested with the white fly.
He used one ounce cyanide (28.35 grammes) for
1,000 cubic feet, and left the plants exposed over
night without injury. The writer fumigated a green-
house in Maryland in which cucumbers were growing
and badly infested with the melon louse (Aphis
gossypii). The house was filled with gas at sundown,
using fifteen-hundredths (0.15) gramme of cyanide per

128 FUMIGATION METHODS

cubic foot, and left until morning. The lice were all
destroyed, and there was no perceptible injury to the
plants. Indian corn, from ten to twelve inches high in
pots standing in one end of the house for experimental
purposes, was destroyed.

Preparation of the house. — The very poisonous
nature of the gas must be considered. The cautions
cited in Chapters III. and IV. should be heeded. The
house should be made as nearly tight as possible under
ordinary circumstances. The ventilators should be
arranged so several of them can be opened from the
outside. Plants that will not stand the stronger doses
of gas, if in pots, should be removed. The room
should not be fumigated immediately after the plants
have been sprinkled or watered. The floor of the
house should not be drenching wet, although it may
be damp.

After estimating the cubic contents of the house,
and the amount of cyanide is determined, the quantity
needed can be figured out according to the directions
given in Chapter XIII. for nursery stock. Care
should be taken, however, to multiply the number of
cubic feet by the exact fraction of a gramme. For
instance, 0.25 gramme cyanide per cubic foot is used
for well-matured and dormant nursery stock, and 0.20
gramme for orchard trees out-doors; but no such doses
are used in greenhouses. Very good results have
been obtained where 0.15 gramme cyanide per cubic
foot has been used in greenhouses and cold frames for
the violet aphis. For other insects and plants the
amount of cyanide varies, as indicated above.

130 FUMIGATION METHODS

How to prepare the jar. — The chemicals should be
prepared strictly in accordance with directions given
in Chapter II. An earthenware crock or jar will be
needed, the size of the vessel depending upon the
capacity of the enclosure. The number of vessels
needed will depend upon the size of the house to be
fumigated. In a small-sized house single jars may be
sufficient, but as a rule it is desirable to use two or
more crocks or vessels. After the acid and water have
been mixed and placed in the vessels, the cyanide,
which has been previously weighed and wrapped in
strong manila paper bags, is suspended over the crocks,
as shown in the illustration.

Several hooks or screw-eyes can be used conve-
niently to carry the string from the door to the vessels.
There should be as many lines of string as there are
vessels, each one leading to the door or outside open-
ing, as shown in Fig. 70. If the building requires
four pounds of cyanide and two jars are to be used, it
is desirable to divide the cyanide into equal parts.
Before the acid and water are placed in the jars, it is
well to tie the bags of cyanide to the cords and see
whether or not they work satisfactorily. Care should
be taken to see that the bags when lowered will go
into the crocks, and thus into the chemicals, without
difficulty.

At times it is necessary to use some protection
around the jars to prevent the injury of the foliage in
case plants are too near. A section cut from a roll of
building paper can be used to good advantage, as the
paper rolls in a tube and can be placed around the
vessel, thus keeping the acid and water from spattering

132 FUMIGATION METHODS

on the surrounding plants. Paper used for this pur-
pose can be rolled together, laid away, and is ready for
future use. When everything is in readiness, doors and
ventilators should be closed, and the cyanide lowered
into the vessels by loosening the strings. The gas is
given off almost immediately and a small quantity will
leak out of the house; but if the room is reasonably
tight the greater portion of it will be kept within for
a time sufficient to destroy the pests. When the
proper time has elapsed, varying, of course, for different
plants, the ventilators should be opened from the out-
side, so that the gas can escape as rapidly as possible.
After free circulation is obtained by opening the doors
and ventilators, all traces of the gas will have dis-
appeared from the house in from thirty to forty
minutes. The house can then be closed if desired.
The residue left in the jars should be emptied, as
previously described.

Boxes for fumigating small plants. — Where it is
desirable to fumigate several hundred small plants,
small boxes, such as described in Chapter XI. , can be
used to good advantage. In most cases a special box,
such as shown in Figs. 47 and 48, is desirable. The
box should be as nearly air-tight as possible, with a
removable cover or trap-door which can be quickly
closed. A special box, shown in Fig. 71, was con-
structed and used by Prof. K. D. Sanderson for the
fumigation of small plants. Small wire or slatted trays
can be used to good advantage for the fumigation of
cuttings, such as coleus and various other plants.
Potted plants can be fumigated in the same box if
necessary.

GREENHOUSE AND COLD FRAME FUMIGATION 133

A plain wooden box, such as is shown in Figs. 49
and 50, or even a small Kmory fumigator, as seen in
Figs. 33 or 36, will be found very useful to florists
and gardeners in any greenhouse or nursery grounds.
This box can be used for the fumigation of small
shrubs and plants on lawns, in gardens, and various
other places where it is desirable to fumigate them
without taking them up. The box may be used in
the daytime if the work is done in a cool place.
Some florists and nurserymen use small boxes in their
packing-houses and cellars where the temperature is
constant. Care must be taken, however, where the
gas is generated and released in such places, to see
that proper ventilation is secured to carry away the
poisonous fumes when released from the box. Nurs-
erymen handling ornamental plants can use their
fumigating houses for the treatment of various shrubs.
Some florists have found that a small greenhouse con-
taining 1,000 feet or less is more reliable than a box.
There is less danger of injury to the foliage under
such conditions.

Experience with various plants. — Although a large
number of greenhouse plants have been fumigated,
there is yet room for much careful experimental work.
The following list of plants, given by Dr. Woods,
have been fumigated.

Ferns. — For Davallia mooreana, infested with a
scale insect {Chionaspis sp.), 0.075 gramme of 98 per
cent, potassium cyanide should be used for each cubic
foot of space to be fumigated, not deducting the space
occupied by the plants. length of exposure, twenty
minutes.

134 FUMIGATION METHODS

One hundred and fifty to two hundred plants with
fronds in all stages of "development have been thus
treated two or three times each year for the past four
years with no injury to the plants and almost complete
destruction of the insect. They were treated fifty at
a time in a fumigating box.

Adiantum cuneatum and A. ballii have been tried
on a small scale and were not injured by the treatment.

Coleus. — Golden Bedder, Verschaffeltii, Shy lock,
and others; 24,000 plants in pots, badly infested with
the white-tailed mealy bug, Orthezia insignis. The
house contained 15,587 cubic feet of space. Treated
at the rate of one-tenth of a gramme of 98 per cent,
cyanide of potash per cubic foot of space for twenty
minutes, one hour after dark. Orthezia all killed and
plants not injured in the least. All other means of
destroying the Orthezia had been tried without effect.
Large numbers of the common mealy bug were also
killed by this treatment; but it was not nearly so
effective as for the white-tailed mealy bug. All coleus
cuttings made by the United States Propagating Gar-
dens for the past few years have been fumigated before
being prepared for the cutting bed.

Double English violets. — Marie Louise, Lady Camp-
bell, and others. For plant-lice and general fumiga-
tion fifteen-hundredths of a gramme of 98 per cent,
cyanide of potassium for each cubic foot of space is
required. The exposure, if made according to direc-
tions, will not hurt the plants in any stage of growth.
The gas has been used on a large scale in fumigating
violets for the past three years with the greatest sue-

GREENHOUSE AND COLD FRAME FUMIGATION 135

cess, only a few treatments during the season being
required. Leaf-eating larvae, slugs, millipedes, cut-
worms, etc. , when exposed are killed as well as plant-
lice. Red spiders, however, are not entirely eradicated
by the treatment. The foliage of single violets, like
California and Princess of Wales, are sometimes slightly
injured by the stronger dose of gas. A weaker dose,
one-tenth of a gramme potassium cyanide per cubic
foot, should be used when they are to be treated.

Other plants. — Other plants on which the gas has
been tried on a small scale indicate that it may prob-
ably have quite a wide range of usefulness. It has
been used on the following plants at the rate of one-
tenth gramme of cyanide per cubic foot of space for
twenty minutes without injury. Further experiment,
however, is necessary before the treatment can be
recommended for these: Alocasia macrorhiza variegata;
Anthurium crystallinum; Areca lutescens; Aralia filici-
folia; Adiantum cuneatum; Adiantum ballii; Campy -
lobotrys refulgens; Cissus discolor; Cretans (in variety)/
Cichorium intybus; Diffenbachia lenmannii; Ficus elas-
tica ; Fuchsias (in variety) / Jacaranda mimosczfolia /
Marantas (in variety) / Nymph&a candidissima, and
odorata rosea; Pontederia crassipes; Pandanus veitchii;
Phrynium variegatum; Phyllotcenium lindenii; Panax
victories; Stenanthium lindenii.

Roses. — Perle des jardins, Mermet, and Bride.
The young growth on roses is particularly sensitive,
and has been more or less injured in all our experi-
ments.

Carnations. — Scott, Garfield, Meteor, and Me-

136 FUMIGATION METHODS

Gowan will stand one-tenth of a gramme of 98 per
cent, cyanide per cubic foot of space for fifteen minutes
without material injury. This will kill about 90 per
cent, of the plant-lice, but will not kill thrips. The
use of the gas for carnations needs to be more carefully
investigated before it is recommended. The same is
true of chrysanthemums, on which it has been tried
with only partial success, the young growth being
very sensitive.

Grapes under glass. — The gas has been used with
success in New Zealand for the mealy bug, DaElylopius
adonidum L,, at the rate of one-third of an ounce 98
per cent, cyanide to 100 cubic feet. This is equivalent
to nine-hundred ths gramme per cubic foot. The gas
is liberated after dark and left in till next morning,
when thorough ventilation is given. It largely
escapes, however, during the night. The treatment
is said not to injure the plants in the least.

Tomatoes. — Dr. J. Fisher, on October 29, 1898,
reports using the gas for white fly {Aleyrodes sp. ) on
tomatoes. The gas from one ounce of pure cyanide of
potassium for each 1,000 cubic feet, left in the house
over night, killed all the insects without injury to the
plants. This method should receive careful trial by
other experimenters.

Other experiments in greenhouses. — For some years
in the large greenhouses connected with the Massa-
chusetts Agricultural College considerable difficulty
has been experienced with mealy bugs and various
species of scale insects on large vines, palms, begonias,
orange trees, acacias, etc. After a thorough trial of

GREENHOUSE AND COLD FRAME FUMIGATION 137

numerous insecticides, hydrocyanic acid gas was used.
The work was placed in the hands of H. D. Hemen-
way. All the results obtained were not conclusive,
and it is impossible to give definite details relative to
future work. Some of these results, however, are in-
teresting, and are given herewith. Other tests should
be made.

After several preliminary experiments with some
of the more delicate plants in a wooden box, two
rooms, known as the stove and cactus, were fumigated
at the same time, the connecting doors between them
having been opened. Many of the cacti were infested
with the common cactus scale, Diaspis cacti. In the
stove-room, all through the twining vines, were white
waxy threads protecting the eggs and young mealy
bugs.

The cactus-room contained 7,076 cubic feet of air
space and the stove-room 7,357 cubic feet. Forty
ounces of potassium cyanide were used in each room,
and they were kept closed for thirty minutes. The
ventilators, which had been previously prepared, were
then opened from the outside. The temperature of
the house was about 60° F. The conditions of the
weather were perfect for such a test, as it was rain-
ing, the water filling all the cracks in the house, and
thus preventing the escape of the gas. It was also
warm outside, so the house was not cooled too low
while the ventilators were open. It was perfectly
dark. The ventilators were left open for about an
hour, and closed for the night.

The room contained many different kinds of cacti,
begonias in variety, passifloras, allamandas, bananas

138 FUMIGATION METHODS

in fruit, ferns, palms, and a large variety of general
stove plants. Not only*were the mealy bugs, scales,
and aphides destroyed, but a large per cent, of sow
bugs were found dead on the walks and under the moss
which covered the floor of the solid bed in the stove-
room. Even the earthworms on the surface of the soil
under the moss were dead.

Another house containing 22,729 cubic feet of space
was fumigated, using one ounce potassium cyanide to
every 285 cubic feet. It contained carnations, smilax,
violets, coleus, chrysanthemums, small lettuce, cut-
tings, and small plants of bedded stock. It was in-
fested with the common mealy bug, Dactylopius de-
structor, green fly, and the white-tailed mealy bug,
Orthezia insignis. It was fumigated for thirty min-
utes upon a cloudy morning, yet in daylight. The in-
sects were mostly killed, but some of the plants were
badly injured. This was especially true in case of the
smilax, the upper leaves of carnations and lettuce.
Much of the latter, which was very small and in full
light, was killed, while some that was shaded showed
much less injury. The smilax and carnations recov-
ered in time, but received a severe check. Smilax and
more delicate plants have been subjected to double
this strength of gas by the writer, in darkness, without
injury.

About the middle of January a camellia-room was
fumigated with one ounce potassium cyanide to every
3,000 cubic feet. The room contained 6,196 cubic feet,
and 2.06 ounces cyanide were used. It was fumigated
at night about six o'clock, and remained closed until
morning.

GREENHOUSE AND COLD FRAME FUMIGATION 139

The insects present were green fly, mealy bug, and
Fuller's leaf beetle. The plants were coleus, azaleas
in bloom, heliotrope, ferns, hoya, jasmins, polygala,
hibiscus, ericas, orange trees, camellias, cinerarias, and
oxalis. The temperature went below 50° F. No
plants were injured. Part of the green flies were
killed, but mealy bug and leaf beetle were not injured.

Another trial was made in the camellia-room just
mentioned a few days later with gas generated from
one ounce cyanide to 2,000 cubic feet of space. The
exposure was continued throughout the night. No
plants were injured. The green flies were all killed,
but only a few of the mealy bugs were destroyed.

A few days later another test was made in the same
room, using one ounce cyanide for each 1,000 cubic
feet. The temperature of the room was slightly above
50° F. With the exception of heliotrope and coleus,
the plants were the same as used in the two previous
tests. All the mealy bugs were destroyed. It would
seem from these tests that the gas can be used in a
greenhouse, under such conditions, generated from one
ounce cyanide in 1,000 cubic feet of space, with good
results upon the common mealy bug.

Many other tests were made, including the vege-
table house. The cyanide was used at the rate of one
ounce for each 3,000 cubic feet of space enclosed. The
temperature was about 56° F. The plants fumigated
were lettuce, radishes, papyrus, smilax, cinerarias, and
kale. The lettuce and cinerarias were badly covered
with green fly. Nearly all green fly was killed, even
under the lower leaves of the lettuce which had com-
menced to head. There was no injury to plants.

140

FUMIGATION METHODS

Estimating cubic contents. — The following excellent
method for determining the cubic contents of a green-
house has been suggested by Dr. B. T. Galloway: In all
cases where fumigation with this gas is to be followed
it is necessary to first determine accurately the cubic
contents of each house. The determination of the

FIG. 72 — DIAGRAM ILLUSTRATING METHOD OF DETERMINING
CUBIC CONTENTS OF GREENHOUSE. (AFTER GALLOWAY)

cubic contents of the house, while in itself a compara-
tively simple problem, has, in the eyes of many grow-
ers, difficulties which they are not willing to under-
take. The cubic contents can be determined by a
comparatively simple mathematical calculation, but
perhaps the easiest way is by the square method.
This involves nothing more difficult than the mere
counting of a number of squares. On examining
Fig. 72 the simplicity of the method will become

GREENHOUSE AND COLD FRAME FUMIGATION 141

apparent. Procure from a stationery store or art sup-
ply store some cross-section paper, such as represented
in the figure. In this particular case squares of three
sizes are shown, the largest being one-half inch, the
next one-fourth inch, and the smallest one-sixteenth
inch square. The one- fourth inch squares may repre-
sent feet. Now determine the dimensions of the
house, that is, the length, width, hight to ridge, and
hight on sides, and make a sketch as shown, each
square or one-fourth inch representing i square foot.
This particular house, it will be seen, is 18 feet (18
squares) wide, 12 feet to the ridge, 6^/2, feet high at
the back, and 4^ feet high in front.

The ridge stands 5 feet from the back wall, as
shown in the sketch. After the lines are drawn, sim-
ply count the squares inclosed, and the number of
squares will be the number of square feet. The parts
of squares, that is, where a line divides a square, can
be easily determined by counting the smallest squares,
or by the eye, and by adding these fractions of squares
together the number of whole squares may be readily
found. After the number of square feet is obtained it
is only necessary to multiply this by the length of the
house in feet and the result will be the cubic contents.
For example, supposing the house in question is 100
feet long, it contains 150^ squares or square feet, and
150^ multiplied by 100 equals 15,050 cubic feet. The
whole operation requires less time than it takes to
describe it, and will apply, of course, to a house of any
shape or size. It may be added that if the cross-
section paper can not be obtained readily the sections
or squares can be laid off with a rule and lead pencil

1 42

FUMIGATION METHODS

and practically the same results obtained. In any
event, it is only necessary to get an accurate outline
drawing of the section of the house, and by projecting
this over squares as indicated the number of square feet
in the section can be readily determined.

The cubic contents of the two styles of greenhouses
shown in Fig. 73 are easily estimated, according to the
following scheme by Professors Woods and Dorsett.
At the left is an even span house 100 feet long, 12 feet
wide, 2 feet on the sides, and 5 feet 6 inches from the

FIG. 73 — EVEN AND THREE-QUARTER SPACE HOUSES AT LEFT
AND RIGHT — END SECTIONS. (AFTER WOODS AND DORSETT)

the surface of the beds to the ridge, with a walk 14
inches wide and 15 inches deep. To determine accu-
rately the number of cubic feet in a house make a
rough drawing showing a cross-section, and divide the
space into triangles and rectangles by drawing a line
connecting the two wall plates and one from the ridge
at right angles to this ; mark on each its respective
length in feet and inches. Compute the number of
cubic feet in each of the rectangles and triangles. In
the even span house, shown at the left, the number of
cubic feet of space in the walk is found by multiplying
the width by the depth by the length, thus: Multiply

GREENHOUSE AND COLD FRAME FUMIGATION 143

I foot 2 inches by i foot 3 inches by 100 feet ; redu-
cing to inches, we have 14 inches multipled by 15 inches
by 1,200 inches equals 252,000 cubic inches ; dividing
this result by 1,728, the number of cubic inches con-
tained in a cubic foot, we have 145.83 cubic feet. The
rectangle A D G F\$> computed in the same way, ex-
cept that in this case it is not necessary to reduce the
feet to inches. It would be 12 feet multiplied by 2
feet by 100 feet equals 2,400 cubic feet.

The rule generally given for calculating the area of
a right-angle triangle is to multiply the base by the
perpendicular and divide the product by 2. The result
multiplied by the length of the house will give the
number of cubic feet the triangular portion contains.
For example, taking the triangle A C E : 6 feet mul-
tiplied by 3.5 feet equals 21 feet, divided by 2 equals
10.5 feet, multiplied by loo feet equals 1,050 cubic
feet. The area of the triangle BCD and the cubic
feet in this part of the house are determined in the
same way ; or, in this case, since the triangles are
equal, the desired result is obtained by multiplying the
number of cubic feet in the triangle ACE by 2 ;
1,050 multiplied by 2 equals 2,100 cubic feet. The
contents of this house is therefore 145.83 plus 2,400
plus 2,100 equals 4,645.83 cubic feet; this result
multiplied by the required dose per cubic foot of space
will give the amount of cyanide of potassium necessary
for one fumigation,

At the right, in Fig. 73, is a cross-section of a three-
quarter span house 100 feet long, 18 feet wide, front
wall 4 feet 4 inches, back wall 6 feet 4 inches, and i
feet 10 inches to the ridge. The cubic contents of this

144 FUMIGATION METHODS

house is determined in the same manner, except that
the two triangles being unequal, each one will have to
be calculated separately. The house contains 15,050
cubic feet. It will thus be seen that the cubic con-
tents of a house or frame of any style can be readily
determined by simply dividing a cross-section of the
same into the necessary number of triangles and reel-
angles, and calculating as demonstrated above.

Cold frames. — That cold frames can be successfully
fumigated has been shown by recent practical work.
Make the frames as nearly air-tight as possible, and
cover them with blankets or canvas if necessary.
Kstimate the cubic contents of air space inclosed, and
then calculate the amount of cyanide necessary. For
example, suppose a frame contained 567 cubic feet.
Multiply this by 0.15, an equivalent of 0.15 gramme
cyanide per cubic foot. Therefore, 567 x 0.15, equals
85.05 grammes; reduced to ounces by dividing by
28.35, as there are 28.35 grammes in an ounce, gives
(85.05 divided by 28.35) 3 ounces the amount of cya-
nide required.

This inclosure would require 3 ounces cyanide, 4^
ounces sulphuric acid and 6^ ounces of water. After
the cyanide is determined it is easy to estimate the
acid and water. Use a half more acid, liquid measure,
than cyanide, and a half more water than acid. Weigh
the cyanide and wrap it in paper or a bag. Measure
the acid in a glass beaker, marked ounces on the side,
and pour it in an earthern jar or china bowl ; measure
the water and pour upon the acid. When everything
is in readiness drop the cyanide, paper and all, into
the liquids and close the frames quickly.

GREENHOUSE AND COLD FRAME FUMIGATION 145

Leave exposed twenty to thirty minutes, and no
longer. Do the work on a dark, cloudy day, or late
in the evening, or at night. Thoroughly air the
frames afterward, and empty the residue in the jars.
Do not inhale the gas, and do not handle the cyanide
carelessly. Both are deadly poison if breathed or
swallowed.

General summary. — (i) The cubic contents of the
house and the amount of cyanide to be used should be
carefully determined. (2) The enclosure should be
made as nearly gas-tight as possible. (3) The venti-
lators should be arranged so as to be opened from the
outside. (4) Place the screw-eyes in their proper
.places and run the string through them. (5) Deter-
mine whether the bag of cyanide is directly over the
jar before the chemicals are placed in it. (6) Measure
the acid and water carefully, place it in the vessels,
hang the bag of cyanide directly over them, and arrange
the protection sheets of paper. (7) The bags should
be lowered by loosening the string from the outside
door. (8) Doors should be properly closed and left
locked the desired length of time. (9) After proper
exposure open the ventilators and doors from the out-
side, and leave them thirty or forty minutes before
entering the house. After that time they can be closed
and left until morning. (10) The contents of the jars
should be buried or thrown upon a manure pile. ( 1 1 )
Jars should be thoroughly washed with cold water and
set away for future use.

A practical application . — In reply to a recent letter,
Edward A. Moseley, of Washington, D. C., says: "I
most certainly believe cyanide fumigation is practical.

146 FUMIGATION METHODS

Last year in my largest Jiouse I only found it necessary
to fumigate once, and until the violets were thrown out
this spring I never saw another aphis in it. I cannot
now give you exact information in regard to the cost
of fumigation.

" I do not entrust the operation to any one, as the
risk, which I believe to be great, I take myself.
Therefore all the fumigation which I have done I have
done alone, except with a friend to assist; but the
people who work about the house have nothing to do
with it. Fumigating is done about an hour or two
after dark. I grow Farquhar, Lady Campbell, and
Imperial violets; also a few La France. Last year I
had some of them in one house. The leaves of the
La France were slightly injured by an exposure of
twenty-one minutes.

"The black aphis were very prevalent; in fact,
the plants were completely covered with them when I
gave the application of which I have spoken, but it
cleaned them out. I have used it also in violet frames
and in a mushroom house. In the latter case I used
it with great strength. I found mice, snails, roly-
polys, and earthworms dead in the morning. This I
put in and allowed to stay all night. I have also
found from experiments that nothing can breathe the
gas and live.

' ' In my opinion no one can successfully grow
violets, at least in this vicinity, who does not use the
gas. I have now one house 23^ feet wide by 200 feet
long, one 20 feet wide by 100 feet long, one 12 feet
wide by 60 feet long, all devoted to the growing of
violets. ' '

CHAPTER XV
SMALL FRUITS AND PLANTS

SIOMK method of destroying plant-lice, leaf- folders,
I and other insects on small plants has long
been sought by economic workers. These
pests can not be reached with sprays, and the
application of certain gases seemed practical. In the
spring of 1898 the writer began a series of experiments
with hydrocyanic acid gas on strawberry plants to
determine the strength that could be used with safety
for the destruction of the root-louse, Aphis for besi.
In these tests it was shown that strawberry plants, dug
in the spring, could be fumigated successfully before
being transplanted. It was found also that the plants
could be dipped in soap and tobacco solutions with
fair results, but the process was slow, expensive, arid
difficult. The gas remedy was cheaper, more certain,
and easier to apply.

Amount of gas for strawberry plants. — With the
ordinary run of strawberry plants as they are taken
from the nursery, two-tenths (0.2) gramme cyanide
per cubic foot, exposed fifteen to twenty minutes, will
be effective in killing the lice without injury to the
plants. The roots should be as free as possible from
dirt, and the plants should be reasonably dry. There
is always more or less moisture on young plants, but
under no circumstances should they be drenching wet
at time of fumigation. Plants should not be closely

i47

148 FUMIGATION METHODS

packed, but laid loosely upon trays in the fumigating
box or room. The details of making and handling
the gas are the same as that for nursery stock and
greenhouse work. The apparatus to be used will
depend upon the number of plants grown and handled
annually. A convenient box for fumigating straw-
berry plants is shown in Fig. 71.

Experimental and practical tests. — At the Dela-
ware Experiment Station a very complete series of
tests were started by Prof. G. Harold Powell and
completed by Prof. K. Dwight Sanderson. Several
infested plants were fumigated and placed in paper
bags, where they were left and examined twelve hours
later. The following amounts of cyanide were found
sufficient for the destruction of the root-louse: One-
tenth gramme (o. i) per cubic foot space, exposed
twenty minutes; fifteen-hundredths (0.15) gramme for
fifteen minutes; two- tenths (0.2) gramme for ten min-
utes; three-tenths (0.3) gramme for five minutes. In
the same series where 0.3 gramme cyanide was used,
all the lice were killed where the exposure was only
five minutes. It is not desirable to use these larger
amounts even for a short exposure. The work by
Professors Powell and Sanderson corroborates the vari-
ous tests of the writer that the two- tenths gramme
formula is satisfactory when properly handled. Under
some circumstances a few lice may be secreted among
the crown leaves and possibly escape where large num-
bers of plants are fumigated. This danger can be
overcome largely by loose packing before fumigation.

Practical tests. — Karly in April Professor Sanderson

FRUITS AND PLANTS 149

fumigated 12,000 Bubach, Excelsior, and Johnson's
Early strawberry plants. These had been packed in
moss while en route from the nursery for nearly a
week, but were in good condition. About 4,000
Tennessee Prolific just dug were also fumigated. The
roots were cut back and fumigated in lots of 1,500 to
2,000 for ten minutes with two-tenths (0.2) grammes
cyanide per cubic foot. The plants were set at once
after fumigation and were not watered. They made a
good stand, very few dying — so few that there was no
question that the gas had done no injury, as two check
rows were left which made no better stand. April 2oth
over 10,000 Bubach plants were fumigated. These
had been dug for one or two days and packed in a
barrel. They were quite wet when fumigated. About
8,000 were fumigated with one-tenth (o. i) gramme
cyanide per cubic foot for ten minutes, and i ,500 at same
dose for fifteen minutes, while nearly i ,000 were planted
unfumigated as a check. After these plants were fumi-
gated they were aired five minutes, roots dipped in
water, and repacked in barrels. They were set. out
three days later. The plants showed no injury from
the gas, all making an equally good stand.

In the experiments of Professor Sanderson the
earth was firmly packed around the open bottom of the
box used. The plants were well cleaned of earth, laid
on trays, the bundles being cut open and thoroughly
loosened. The lid of the box was then closed and
fastened. A coffee cup or similar vessel was placed in
the lower corner of the box by the door, and into it was
first dropped a vial containing a proper amount of the
cyanide in solution. A vial containing the sulphuric

150 FUMIGATION METHODS

acid was then dropped in and the door quickly closed.
The vials were dropped in with the mouths down, and
the contents drained out gradually, avoiding a puff of
the gas by too rapid generation. The box was kept
closed for ten minutes, or as long as desired. Both
doors were then thrown open and the trays lifted out,
so that the plants were thoroughly aired.

The cyanide solution should be secured from a
druggist, put up in homeopathic vials, one dose in each
vial. The solution consists of* 100 grammes 98 per cent,
potassium cyanide dissolved in water to make 200
cubic centimeters solution. The amount necessary for1
each dose is easily computed: multiplying the cubic
contents of the box by 0.4 will give the number of
cubic centimeters of the solution to be used, this giving
a strength of o. 2 gramme potassium cyanide per cubic
foot. Use an equal amount of sulphuric acid, which
can be readily measured into empty vials. Thus for a
box 2 x 2 x 2^£ feet, or 10 cubic feet, 4 cubic centi-
meters of the solution, or a two- drachm vial half full,
and an equal amount of sulphuric acid (best grade
commercial, 1.85 specific gravity) would be used for
a strength of 0.2 gramme potassium cyanide per cubic
foot, or the same vial three-quarters full for a strength
of 0.3 gramme potassium cyanide per cubic foot.

Small plants in the field. — For individual plants,
such as melon, cucumber, cabbage, etc. , a small cover
is needed. In many cases where only a few plants are
to be treated, a two-gallon wooden pail or other simi-
lar vessel will do. Paper or canvas covered boxes, one
or two feet square at the base, and fifteen to twenty
inches high, can be made cheaply and used to good

FRUITS AND PLANTS 151

advantage. In his experiments Professor Sanderson
used small paper covers, pyramidal in shape, the apex
being eight inches high and fastened to the inside of a
wooden frame three inches high by twenty inches
square. The lower edge of the frame was beveled on
the lower edge and could be easily pressed into the
soil. A good quality of building paper, cut in one
piece, can be used as covers. The cost of the covers
complete should not exceed four cents each.

After making over seventy-five tests Professor
Sanderson is of the opinion that about four- tenth (0.4)
gramme cyanide per cubic foot exposed ten minutes
is sufficient. In some tests young cantaloupes, fumi-
gated immediately after a shower, were somewhat
injured. The plants should be as dry as possible and
the amount of cyanide reduced to three-tenths (0.3)
gramme per cubic foot in some cases. The seemingly
large amount of gas used on these low-growing plants
is due to the fact that a larger proportion is lost in the
small covers than in a large enclosure. Where plants
are 5x5 feet apart, the cost of fumigation per acre,
even at the maximum amount, is about seventy-five
cents for chemicals. Two men with one hundred
covers should fumigate from three to five acres per
day, depending somewhat on conditions.

Plants in rows. — The fumigation of plants in rows
is rather difficult and expensive. To compensate for
the influence of soil and foliage, a larger amount of
gas per cubic foot of space must be used to accomplish
the same results than in a box or other enclosure.
Prof. C. L. Penny, chemist at the Delaware Experi-
ment Station, has shown conclusively by analyses that

152 FUMIGATION METHODS

when the gas is used in an elongated space the amount
of cyanide per cubic foot is no guarantee, on the one
hand, of sufficient acid vapor to do the work, nor, on
the other, of too little to injure the plants. These
tests show also that a large amount of gas may be ab-
sorbed by the film of water on damp foliage, or by the
soil in a frame with the bottom open.

In field tests, therefore, a larger amount of gas than
that used in the laboratory in a closed box was re-
quired to compensate the influence of soil and foliage.
In a ten-foot frame, triangular in cross-section, with a
cubic capacity of 8^ feet, or a ratio of 2^ soil surface
to one of volume, Professor Sanderson found just
twice as much gas was required to be generated
from two points to be effective as that in a wooden box
containing 10 cubic feet capacity and 5 square feet
soil surface, having an almost opposite ratio of two
of volume to one of soil surface. The materials and
cost of constructing frames for the fumigation of plants
in rows is slight. Frames, triangular cross-section 10
feet long by 10 inches high and 24 inches wide at the
bottom, have been found very satisfactory by Professor
Sanderson. With twelve such fumigators an acre of
plants, where the rows are three feet apart, can be gone
over in about two days. The cost of chemicals, not
including labor, would be about three dollars per acre.

CHAPTER XVI

APPLICATION IN MILLS, ELEVATORS, AND
OTHER ENCLOSURES

M^^ANY gases and other materials have been used
in mills and other enclosures for the de-
struction of insect pests. Gas generated from
sulphur is not only dangerous to inhale, but
is liable to injure manufactured products. The writer
reported several years ago the serious results upon
manufactured products in a mill where sulphur fumes ,
were used. Smoke or fumes generated from tobacco
are not desirable on account of the disagreeable odor
and the after-effects upon grain and the manufactured
products. Both of these materials being generated
with fire, the danger attending application in mills
and other places is increased, and their use is seriously
objected to by insurance companies.

On the other hand, carbon bisulphide has many
advantages over sulphur and tobacco ; it can be used
without danger of injuring either the grain or manu-
factured products, and is generated without the use of
fire. Yet many insurance companies will not permit
their patrons to use it, except at their own risk, on
account of its explosive nature when the fumes are
mechanically mixed with air. It is, perhaps, the safest
and most reliable remedy suggested for use in build-
ings and other enclosures where large quantities of
grain and other materials are stored, due largely to
the fact that its fumes are heavier than air.

Sometimes it is desirable to use carbon bisulphide

153

154 FUMIGATION METHODS

in connection with hycjrocyanic acid gas in buildings
and other enclosures. On one occasion the writer had
a large quantity of grain badly infested with insects
stored in an old building. The wheat was confined
in several large rooms more or less open. Carbon
bisulphide was used liberally for the destruction of the
insects in the grain, but it was found that a large
number of the creatures in the upper part of the build-
ing escaped, owing to the openness of the enclosure.
The building was made as tight as possible by hang-
ing blankets, fertilizer bags, etc. , over the cracks, and
a charge of hydrocyanic acid gas was liberated.
Double the quantity ordinarily recommended for a
tight enclosure was used. The experiment was largely
successful, and the insects were thoroughly destroyed
both in the grain and throughout the building. It is
not desirable, however, to generate the twro gases at
the same time. In this instance the hydrocyanic acid
gas was applied forty-eight hours after the carbon
bisulphide was used.

The strongest arguments in favor of hydrocyanic
acid gas are: (i) it is generated without fire; (2) it is
comparatively cheap; (3) non-inflammable and non-
explosive when generated with normal amounts; (4)
does not injure grain or manufactured products,
machinery, furniture, or equipment of any kind; (5)
leaves no odor or residue after fumigation; (6) is
lighter than air, and quickly permeates all cracks and
crevices in which pests hide; (7) can be used at night
or in the daytime at pleasure; (8) creates a death
atmosphere in which no animal can live, including rats,
mice, and other vermin; (9) its very deadly nature

MIU,S AND OTHER BUILDINGS 155

when inhaled lessens the possibility of accident, and
(10) it affords insurance companies and others all the
protection possible under such conditions.

First use of hydrocyanic acid gas in mills, etc. — The
use of hydrocyanic acid gas for the distraction
of insects in mills, elevators and other large enclosures
where grain is stored and manufactured was first
suggested by the writer in an article in the American
Miller for March, 1898. Up to that time, we believe,
no attempt had been made to fumigate large buildings
with this gas for the destruction of vermin. In this
article attention was called to a large mill in North
Carolina, overrun with cockroaches, and the following
statement was made : ' ' We are going to try a new
remedy. It has never been used, to my knowledge, for
destroying insects in mills. It is simple and easy to
apply, but a very dangerous and deadly poison, and
must, like dynamite, gunpowder, kerosene, or carbon
bisulphide, be handled cautiously and by expert
hands. Our new remedy is hydrocyanic acid gas, one
of the most deadly poisons known. I have used this
gas in my experimental work the past two years
for killing insects upon young fruit trees, nursery
stock and in bearing orchards, and in buildings for
destroying rats, with marked success. I will now
apply it to the modern mill and storehouse, and my
candid belief is that it will be one of the coming
remedies for all vermin, including rats and mice, within
such enclosures. ' '

The opportunity did not offer itself at the time for
the experiment and we were obliged to let the matter
drop. The spring of 1899, however, offered us a

156 FUMIGATION METHODS

chance to use the gas in a granary and storehouse.
The results were so gratifying we decided to apply the
same methods to a modern mill, if an infested one
could be found and the owner would consent to the
experiment. Two infested mills where we could try
the gas on a large scale were soon found. Both
contained three stories with basement and attic. One
was 70 by 40 feet and the other 50 by 50 feet. Before
filling an entire building with the gas, we decided to
confine our experiment to one floor. All arrange-
ments were made with a Pennsylvania miller and final
directions were sent for the work. The first charge
was set off June 10, 1899, using five pounds of
potassium cyanide, an equivalent of o. 10 gramme
cyanide per cubic foot of space enclosed.

Five days later the following letter was received
from the owner: " We made use of the chemicals sent
us, as directed, on the loth instant, and had some
success, at least enough to convince us that through
its use we can retain possession of our mill. Most of
the weevil on the first floor are either on the floor or
very close to it, and we find that a good many of them
escaped punishment. In the rooms above the first
floor we will have a better chance at them, they being
higher up in places where we can not get at them
with anything but gas. We would like to have you
arrange to send us enough of the potassium cyanide to
go through our mill from the first floor up. Any
information you can give us concerning the second
treatment will be greatly appreciated. We found a
dead cat on the mill floor when we went in after airing
the room thoroughly. ' '

MILLS AND OTHER BUILDINGS 157

This experiment was thoroughly satisfactory, and
being the first of the kind ever tried in a mill, so far
as known, was of special importance. Where only a
single floor is fumigated, we would naturally expect
some insects in the floor and beneath it to escape, as
the gas is lighter than air and rises. A room, there-
fore, would have to be perfectly tight, and enough
gas generated to fill it before the fumes would reach
the floor and penetrate the cracks and crevices. It
would be only a few moments after fumigation before
insects would again come through the cracks in the
floor from the basement below and perhaps the floor
above.

To be successful in the greatest degree the mill
should be thoroughly filled at one time with the gas.
For instance, if only a single room or floor is used and
the gas is generated, the insects become very uneasy
when they begin to feel uncomfortable, and run here
and there in search of a crack through which to
escape; but if every room is full of gas there is no
possible means of escape, except through some crack
leading outdoors.

Second experiment in mills. — In an Ohio mill,
June 20, 1899, we tried another experiment on one
floor only, using ten pounds of cyanide at the rate of
0.12 gramme per cubic foot of air space. The
chemicals were placed, according to my directions, in
the hands of an expert chemist. June 3oth the owner
sent a sample of web and material from the room, and
wrote me as follows: "I send you by mail, under
separate cover, a sample of moth, weevil, and bugs the
gas destroyed. I wish to thank you for what you

158 FUMIGATION METHODS

have done for me and to tell you that the experiment
was a grand success."

A careful examination of the material sent showed
seven species of dead insects, as follows: (i) Flour
moth, Ephestia kuehniella, adults and larvae; (2)
bolting-cloth beetle, Tenebroides mauritanicus, adults;

(3) American meal worm, Tenebrio molitor, adults;

(4) flour weevil, Tribolium confusum, adult and
larvae; (5) black carpet beetle, Attagenus piceus,
adult; (6) a lady beetle, and (7) a hemipterous insect.
The latter two were, no doubt, feeding upon some soft-
bodied creatures, as they are both predaceous. This
web, flour, dust, and insects was placed in a breeding-
cage and was under daily observation for three weeks
and no life made its appearance. When the package
was received one living specimen of the flour weevil,
Tribolium confusum, was found. It was, no doubt, a
straggler from some crack where the death atmosphere
did not reach.

From recent results we are convinced that this gas
is one of the most powerful and penetrating materials
ever used in a mill or other buildings for the
destruction of vermin. It diffuses so readily that it
will permeate all parts of a mill or enclosure in a few
minutes. It is a deadly poison if inhaled by a human
being, it is true, but there is no necessity of one
breathing the fumes if the proper precautions are
taken. The writer is satisfied that by its use many
a miller can retain possession of his mill who would
otherwise be obliged to give it up and acknowledge, in
the "struggle for existence," it is the '' survival of
the fittest ' ' that wins out. It is humiliating, indeed,

MILLS AND OTHER BUILDINGS 159

to be forced to concede that the flour moth or weevil
is the fittest thing in existence, but some millers have
actually been forced to abandon their mills on account
of these insect foes.

Necessary preparations. — In fumigating a mill, ele-
vator, warehouse or other enclosure containing stored
grain or manufactured products, several things are to
be taken into consideration.

1 . The nature of the structure has a great deal to
do with the effectiveness of the remedy. As the gas is
lighter than air and very penetrating, it would soon
escape and lose its deadly effect upon animal life in a
building more or less open.

2. The weather conditions have to be considered.
It is not desirable under any circumstances to fumi-
gate an enclosure when the wind is blowing. A calm,
quiet day or night should be selected for the work.

3. The building should be made practically gas-
tight by closing up all the cracks and external open-
ings. This can be done best by pasting strips of ordi-
nary paper over the cracks. Special attention should
be given to windows and doors, and they should be
thoroughly secured before the gas is generated.

4. There should be no lights or fire in the build-
ing while it is filled with gas. It is non-explosive
when used according to normal dose ; but to preclude
possible accident it is best to be on the safe side, thus
this suggestion.

5. In a mill all machines, chests, spouts, eleva-
tors, elevator legs, bins, barrels, boxes, etc., should
be opened, and all unnecessary material should be
removed and burned before the chemicals are placed.

l6o FUMIGATION METHODS

6. A door and several windows or other open-
ings should be adjusted so they can be opened from
the outside to permit the escape of the gas after
fumigation is completed. Where convenient several
windows on each floor should have .the top sash ar-
ranged so they can be lowered by means of a rope
from the outside. In this manner ventilation is per-
fect and the gas soon escapes.

7. A special watchman should be detailed to look
after the fumigation and guard the premises while the
gas is enclosed and after it is released.

8. In buildings where several rooms or floors are
fumigated at the same time, each room or floor should
be shut off from the other as much as possible. Where
open stairways lead from one floor to another, it will
be necessary to cover them temporarily with light
boards, over which can be thrown old bags, sacks,
blankets, etc. Care should be taken not to blockade
the stairway so the operator cannot readily escape
when the gas is generated. By closing the doors be-
tween the rooms and covering the stairways the gas is
kept at a very uniform density in each room for a
longer period.

Making the gas. — The chemicals used for making
hydrocyanic acid gas are potassium cyanide, sulphuric
acid and water. Special directions for combining these
chemicals for generating the gas are given in Chapter
II. These instructions should be carefully studied and
followed specifically, as the process will admit of no
guesswork. The cautions cited should be heeded and
considered at all times. The acid is first placed in a
crock of earthenware or a wooden vessel and the water

MILLS AND OTHER BUILDINGS l6l

poured upon it. The cyanide is afterwards dropped
into the liquid, bag and all. The acid soon eats
through the paper and a bubbling reaction follows,
similar to that produced by placing a piece of red-hot
iron in cold water. This lasts a few moments only,
or until the acid acts upon the cyanide.

A cloud of white steam is almost instantaneously
disseminated throughout the room or enclosure. The
odor of this gas is decidedly that of peach pits, and is
therefore easily detected. It is considered one of the
most deadly poisons known to chemical science and is cer-
tain death to any animal inhaling it. If a person
should breathe his lungs full of it he would not live
to know when he took his second breath, if he got it
at all. Attention has been called to the dangerous
character of the cyanide and this gas in each chapter,
and the writer again cautions those who are interested
in the subject to handle the material with great care.
When so handled there is no danger whatever, and
the results are satisfactory in every respect. The
effects on animal life given in Chapter IV. should be
carefully read in this connection.

Resisting power of insecJs. — After much experi-
mental work and many practical tests, we have found
that the most resistant insects infesting grain and
manufactured products are destroyed when the gas is
generated at the rate of 0.25 gramme cyanide per
cubic foot of space enclosed. The adults of the Med-
iterranean flour moth, Ephestia kuehniclla, the Angou-
mois grain moth, Sitotroga cerealella, and the Indian
meal moth, Plodia interpunctella , are destroyed readily
with 0.12 to 0.15 gramme cyanide per cubic foot. The

1 62 FUMIGATION METHODS

difference in the resisting powers of various species of
insects is so slight we generally recommend for indoor
fumigation the use of the 0.25 gramme formula. Un-
der no circumstances should a less amount be used,
unless specifically designated by an expert.

Some beetles require the full strength to destroy
them in most enclosures. This is particularly true of
the bolting-cloth beetle, Tenebroides mauritanicus , and
its young, a small, flat, whitish, greasy-looking crea-
ture, about one-third to one-half inch long, familiar to
millers ; the flour beetle, Tribolium confusum, and its
young ; the grain weevils, Calandra granaria and C.
oryza ; and the American meal worm, Tenebrio molitor.
In fact, nearly all the beetles commonly found in mills
and other enclosures where farinaceous foods are stored
or manufactured are not as easily killed with the gas
as moths and their young. Bearing these facts in
mind, it is, therefore, best to use the gas in accordance
with the 0.25 gramme formula.

Estimating chemicals. — The amount of cyanide
necessary for any enclosure is determined in terms of
grammes per cubic foot of space enclosed. To deter-
mine the exact amount of cyanide necessary to fumi-
gate a room, car, ship, or building of any kind, the
cubic contents must be accurately computed. As an
example, a room 20 x 30 x 10 feet contains 6,000 cubic
feet of air space. To estimate the amount of cyanide
required for this enclosure, multiply 6,000 by 0.25 ;
thus: 6,000x0.25= 1,500 grammes. To reduce this
to ounces, divide by 28.35, as there are 28.35 grammes
in an ounce; thus: 1,500-4- 28.35 = 53 ounces, the
exact amount of cyanide needed for the enclosure. It

AND QTHER BUILDINGS 163

is now easy to determine the amount of acid and water,
as a half more acid, liquid measure, than cyanide, and
a half more water than acid are used; thus: 53-1-2
= 26.5, which, added to 53, equals 79.5 ounces of acid,
or practically 5 pounds, liquid measure. Again, 79.5,
or practically 80, as we usually discard fractions,
divided by 2 equals 40, which added to 80 makes 120
ounces of water.

Therefore, a room 20 x 30 x 10 feet requires 53
ounces, by weight, of cyanide, 80 ounces, liquid
measure, sulphuric acid, and 120 ounces, liquid meas-
ure, water. The total cost of chemicals will be about

$1-25-

Application. — The methods used for generating the
gas in large enclosures, such as a mill or other building,
is not unlike that illustrated in Fig. 70, Chapter XIV.
In our early experimental work it was thought desir-
able to weigh the cyanide in bags of one pound each,
but more recent practical tests have shown that
it is more economical and satisfactory to have it
weighed out in packages of three pounds each. Where
used in this manner the jars or wooden vessels for
acid and water should hold two or three gallons
each.

If, for example, we had a room in which 18
pounds of cyanide were required, it would be weighed
out in six packages of three pounds each. Each
package will require a separate generator; therefore,
six crocks or wooden vessels will be necessary. They
should be arranged at various places in the room.
Strings should be arranged so as to hang directly
over each vessel, and carried through screw-eyes in

164

FUMIGATION METHODS

the ceiling or woodwork to the door or stairway lead-
ing out of the room, as shown in Fig. 74.

The screw-eyes should be firmly secured, and only
strings of good quality used. The bags of cyanide
should be thoroughly fastened and suspended over the

FIG. 74 — DIAGRAM SHOWING THE INTERIOR ARRANGEMENT OF
AN ENCLOSURE READY FOR FUMIGATION

vessels before the acid and water are placed in them.
A small wire hook, as shown in the figure, can
be used, but a string tied firmly around the neck of
the sack is less trouble and more secure. With each
three-pound bag of cyanide use 4^ pounds, liquid
measure, sulphuric acid, and 6^ pounds water.

The operator should begin on the top floor, lower
the cyanide into the jars containing the acid and
water, quickly close the door or other opening, and

MILLS AND OTHER BUILDINGS 165

get out. The next story should be handled in the
same manner and the room closed. Kach floor below,
including the basement, is handled the same way.
Whenever the gas is generated in a basement, cellar,
or in a room where the operator can not get out
quickly without climbing a ladder or going up-stairs,
great care should be taken. The lines of string lead-
ing from the cyanide should be arranged so they can
be cut from a point where the operator will have no
difficulty in escaping quickly. Under no circum-
stances should one go into a basement or other
enclosure, unite the chemicals, and attempt to escape
by climbing a ladder or stair. Such a procedure would
be exceedingly hazardous and should be avoided.

Outside doors or other openings in buildings where
persons are admitted should be carefully locked or
barred, so that no one could possibly enter while the
gas is enclosed.

Airing the enclosure. — In buildings where large
quantities of grain, manufactured products, or other
materials, are stored the gas should be left, where it is
convenient to do so, from five to twenty- four hours, or
even longer. During this time more or less of the gas
will escape, and when the doors or ventilators are opened
great care should be taken not to inhale the escaping
gas. The building should be left open and allowed
to thoroughly air for half an hour or longer before
anybody is permitted to enter it. In tight enclosures,
such as basements and lower rooms, where free
circulation is not available, a longer time may be
required to eliminate the gas. In such cases extra
precaution should be taken. If there is the slightest

1 66 FUMIGATION METHODS

indication of the peach^pit odor, the enclosure should
not be entered until after it has disappeared.

Residue in vessels. — The material left in the vessels
after fumigation should be handled carefully. It is an
excellent fertilizer, and can be used for that purpose if
composted with earth or other material. Where
available, it can best be utilized by throwing it upon
a manure pile. Wash quickly in cold water, if by
accident the acid is gotten upon the flesh. The
chemical composition and value of the residue is given
fully in Chapter II.

Cars and ships. — Not infrequently railroad coaches,
street-cars and ships become badly infested and over-
run with vermin of various sorts. Such enclosures
can be readily fumigated with hydrocyanic acid gas by
following the directions given herewith. In South
Africa some railroad companies have found it
expedient to fumigate their passenger coaches to
keep them free from bedbugs and other pests.
Very often ships are overrun with cockroaches, fleas,
bedbugs, etc. The gas can be supplied in such places
with perfect success for the total destruction of the
vermin. In any case whatever enclosure is to be
fumigated the same precautions and methods for
handling and generating this gas should be observed.

Dwelling-houses and storerooms. — This gas can also
be used with perfect safety in the hands of an expert
in dwelling-houses or storerooms infested with the
ordinary household pests. In such cases, however,
great care should be taken in handling the material,
and no person should be allowed to remain in the

MILLS AND OTHER BUILDINGS 167

house during the process of fumigation. It has re-
cently been applied in a room of the Division of
Botany, United States Department of Agriculture, by
W. R. Beattie, for the destruction of cockroaches. He
recommends the use of the gas at the rate of o.io to
0.22 gramme cyanide per cubic foot for the destruc-
tion of flies, cockroaches, moths, etc. For fleas and
bedbugs the writer has found that a dose varying from
0.20 to 0.22 gramme cyanide per cubic foot is far more
desirable.

This method will be found very useful in clearing
large hotels, dwelling-houses and other buildings used
as summer resorts of undesirable pests. The gas
should be applied at a time when the buildings are
not occupied. On account of its very rapid diffusion,
from three to twenty-four hours will accomplish the
desired results. No fumigation for less than three
hours is recommended for household pests. Under no
circumstances should it be used in a house or other
building occupied by other individuals, either above,
below, or on either side of the room or apartment
fumigated. The gas will in no way injure any article
of furniture found in the ordinary household, Care
should be taken, however, to remove all edible mate-
rials. Water used for drinking should not be left in
the room. The gas should not be handled by persons
who are not thoroughly familiar with its deadly na-
ture. It is, therefore, not generally recommended for
use in houses unless applied by an expert.

Explosive properties. — In all our experiments and
recommendations we have kept the amount of potas-
sium cyanide considerably below the danger limit, so

1 68 FUMIGATION METHODS

far as combustion is concerned. The gas is non-ex-
plosive when used at or below 0.25 gramme potassium
cyanide per cubic foot of space enclosed, other condi-
tions being normal. We have asked Dr. H. W.
Wiley, Chief of the Bureau of Chemistry, United
States Department of Agriculture, for his opinion re-
garding this matter, and quote the following letter
from him :

"Cyanogen gas, or hydrocyanic acid gas, mixed
with air or oxygen, forms an explosive mixture, but I
should not think that in the proportions you mention,
viz., 0.25 gramme of potassium cyanide for each cubic
foot of air space, it would produce an atmosphere
which would be explosive. Hydrocyanic acid, how-
ever, is combustible and could be mixed with air, I
presume, so as to form an explosive mixture. I have
looked over the authorities, but can find no mention
of explosive properties.

' ' The danger of hydrocyanic acid, in my opinion, is
not from its explosive properties, but from its highly poi-
sonous nature. Small quantities of hydrocyanic acid
gas inhaled are extremely poisonous, and are apt to
produce fatal results. // would be equivalent to instant
death for any one to enter a building filled with it.

' ' While I do not think there would be danger of
an explosion in the proportions you mention (0.25
gramme), I would advise great circumspection in the
introduction of a light, unless it be an incandescent
electric light, enclosed in an air-tight globe. Such
lights should always be used where there is any danger
of explosion. ' '

Practical application. — The following testimonials

MILLS AND OTHER BUILDINGS 169

from a large number of individuals throughout the
country, who have used hydrocyanic acid gas in mills,
warehouses, elevators and other places, are sufficient
to corroborate the statement that it is of very great
economic value when used in such places. In quot-
ing these letters all reference to individual and firm
names has been omitted purposely. The following is
a letter from a Utah milling firm who used this gas
recently :

We procured the necessary chemicals and proceeded
to carry out your instructions specifically. We believe
that we are safe in saying that the experiment was
entirely successful, (i) because on leaving the build-
ing, after dropping the chemicals into the water and
acid, we heard the bubbling described by you, thus
proving that action took place between the cyanide
and the adulterated acid; (2) when we opened the
door of the building, after leaving it closed as directed,
two dead pigeons were found (we had placed them
in the building purposely), the gas had entirely filled
the enclosure, as the two birds were in different
places in the rooms; and (3) the best proof that
the experiment was successful is the fact that we
cannot find any trace of the pests which formerly
existed, even though warm weather is here. We
wish again to thank you for the interest taken in this
matter, as well as the favors extended to us.

Tobacco warehouse. — The writer personally con-
ducted the fumigation of a five-story brick building in
Baltimore, September 18, 1900, infested with insects
{Lasioderma serricorne}, injuring leaf tobacco in store,
and the method was thoroughly successful. Fifty

1 70 FUMIGATION METHODS

pounds of cyanide wei^ used in this building at one
time. The four upper stories were fumigated first,
and a few days later the basement and first floors.
We demonstrated that this gas can be used even in the
heart of a solidly built-up city block if properly
handled. The building in question is located in the
heart of the business center of the city. Bvery crack
about the windows was pasted up with narrow strips
of paper. We used string and bags, suspending 3^
pounds of cyanide over each four-gallon jar. We had
six jars each on the second and third floors and two
each on the fourth and fifth floors. The gas was gen-
erated after office hours at 7.30 and the windows were
lowered from the outside about 12 o'clock, midnight,
the same night. The windows in the fifth story were
lowered first, and by opening a door below a draft was
created through the elevator shaft carrying the bulk
of the gas out above the building. The other windows
were opened a few minutes later and the building
aired the rest of the night, one man remaining on
guard all the time. The results were very gratifying.
The pests were thoroughly destroyed, and in addition
seven dead rats were found on the basement floor and
one on the third floor.

Mills and elevators. — The following is from a Cana-
dian firm : In connection with our use of hydro-
cyanic acid gas for the extermination of the Mediter-
ranean flour moth, we beg to report the following :
The cubic contents of our buildings figure 290,472
cubic feet, for which we used 151 pounds cyanide of
potassium, 226 pounds sulphuric acid, and 338 pounds
water. We distributed 150 crocks throughout the

MILLS AND OTHER BUILDINGS 1 71

buildings, as directed by you, putting about an equal
number on each floor, and into each crock we put i >^
pounds sulphuric acid and 2^ pounds water. We
then weighed out 151 pounds of cyanide and put this
up in manila bags of i pound each ; each bag was
tied with a string, upon which was left a loop. We
placed screw-hooks into different parts of the wood-
work, spouts, elevator legs, etc., passed through the
hooks stout twine, so arranged that it would come
directly over the center of each crock. Just where the
string passed over the crock we tied an S-hook, on
which we hung the bags of potassium.

The stairways leading from the basement to the
top of our mill go up at the side and nearly at the end
of the building, one stair directly above the other.
At the side and the ends of the mill farthest from the
stairway we started six different lines of string, tying
one end of each line to the opposite wall, and leading
each string to the stairway by a different route over
the floor and tying each string tightly to the stairway
rail. At the proper moment all the strings on the
floor could be cut at the same time, and all the little
bags of cyanide would fall immediately into the solu-
tion of acid and water.

Each opening at the stairs had been provided
with a tight door. The man who cut the strings
started at the top floor, worked downward, cutting
the strings on each floor as he passed through and
closing the door behind him quickly, so that it was
impossible for even a whiff of the gas to reach him.

We cut these strings at 8 o'clock Saturday night
and placed a man on guard all night. The odor

172 FUMIGATION METHODS

of the gas was quite, noticeable twelve feet away
from the mill, although every precaution had been
taken to close all the cracks by pasting strips of
paper around the window-sash and door-frames, and
otherwise making the mill as tight as possible. We
opened the building at 9 o'clock Monday morning
and could not detect more than the faintest odor of
the gas. A careful examination showed the floor
plentifully sprinkled with moths, flies, spiders, and
occasionally a mouse or two. We examined care-
fully for the grubs or larvae and found plenty of them
dead, and but two or three alive in a mass of flour,
but these were not by any means lively. We have
watched carefully ever since, over two months, and
have seen only an occasional moth. We believe it
is impossible to find a moth in our two buildings
to-day.

We are delighted with the results of this gas. In
our case it has certainly been a decided success. We
would say to any one intending to use it they should
take every precaution to have the manila bags of good
quality. The cyanide of potassium liquidizes after
being placed in the bags and exposed to the air. It is
apt to drop into the solution by the bag becoming wet
and tearing at the bottom before the strings are ready
to be cut. In conclusion, we wish to express our
hearty appreciation of your painstaking care in the
instructions of the use of this gas and also for your
personal letters to us with regard to certain particulars.

The following report is from a Western miller :
After carefully reading your instructions and closely
following them, we fumigated a i5o-barrel mill with

MIU<S AND OTHER BUILDINGS 173

marked success. We allowed the gas to remain in the
building one night and day. The next morning we
found everything had perished, including many mice
and weevil. The last day or so we have noticed one
or two weevil, probably some that survived by being
deeply buried in cracks. We can certainly speak a
good word for the remedy, and thank you very much
for your instructions, which has aided us in free-
ing our mill and warehouse from such troublesome
pests.

Repeated applications demonstrated that the remedy
is one that can be relied upon when properly used.
An occasional miller, however, may get a bad lot of
chemicals and can not generate the gas properly. One
of our Canadian friends wrote recently that he was not
very successful in his fumigation, stating that the
cyanide did not work in the acid and water. It was
apparent to me he had used an old grade of cyanide,
about 58 per cent, purity, where he should have had
the chemically pure cyanide, guaranteed 98 to 99 per
cent. My suspicions were well founded, and a few
days later, at my suggestion, he tried the pure cyanide
with good results and wrote me as follows August 15:

Your letter of July 22 was duly received and care-
fully noted. About ten days ago we fumigated again
with the hydrocyanic acid gas, and this time with
complete success, hardly a bug or grub of any kind
being left alive. We see an odd one occasionally, both
moth and weevil, and we expecl; there will be some
hatched out from eggs left. We shall fumigate again
in another month or so if necessary. The fumigation
is so simply done, and so deadly, that we have now no

174 FUMIGATION METHODS

fear but what we can keep our mill free in the future.
We removed all flour, with exception of a few samples,
but on these we could discover no taint. Our failure
before was owing to inferior cyanide, just as you said,
and was our chemist's fault entirely. We again thank
you for your advice and information.

Successful application in house and laboratory. — The
writer, knowing that Dr. H. J. Webber, of the United
States Department of Agriculture, who is in charge of
the Laboratory of Plant Breeding, had used hydro-
cyanic acid gas successfully in a dwelling-house, wrote
him for an account of his experience and received the
following reply :

' ' I had one experience in Florida in fumigating a
rented house for various household vermin. While
such a matter is usually considered strictly a private
affair, I have no objection to giving you the following
brief note : While living in Florida we moved into a
house which was found to be infested with cockroaches
and bedbugs. In order to rid the place of these pests
it was fumigated with hydrocyanic acid gas, using one
ounce of potassium cyanide to each 100 cubic feet of
space in the house. The fumigation was started very
early in the morning and continued for about six
hours, when the windows and doors were opened and
the rooms thoroughly ventilated. The house was
occupied that night as usual, there being only a slight
odor of the cyanide perceptible. The effect of this
fumigation was marvelous. I have never, before or
since, seen a house so thoroughly cleared of insects. ' '

In the same letter Dr. Webber says they were
greatly bothered last summer, in their Washington

AND OTHER BUILDINGS 175

laboratory, with cockroaches, the so-called "silver
fish," and the Angoumois grain moth. C. P. Hartley,
an assistant in the laboratory, had the building fumi-
gated with very excellent results. At the suggestion
of Dr. Webber the following statement of facts was
furnished by Mr. Hartley :

' ' During the summer of 1901 one of the laboratories
of the United States Department of Agriculture became
badly infested with mice and insects of many kinds.
It was decided to try the efficacy of hydrocyanic acid
gas in ridding the building of these pests. This labora-
tory had become the abode of cockroaches, beetles,
crickets, moths, flies, etc., to some extent because it
was connected with greenhouses where these insects
abounded, but more especially because of seeds, fruits,
and plant specimens that were stored in the vari6us
rooms. The entire building, a two-story frame struc-
ture of eight rooms, was twice fumigated during the
latter part of the summer with such success that the
building was free from insects for the rest of the year.
The first fumigation was given the latter part of
August and freed the building for a week or more,
after which time many small roaches and other young
insects became noticeable which probably developed
from eggs in the building.

* * For the first fumigation old stock potassium
cyanide from several sources and of various appear-
ances was used, but for the second, ten days later,
fresh material was used, and resulted in killing every
insect and mouse in the building. This fumigation
was started at four o'clock in the evening and the
building was kept closed until the next morning, when

1 76 FUMIGATION METHODS

it was opened and occupied during the day. The only
injurious effects of the gas were on the mice and in-
sects in the building, but the precaution had been taken
to remove the unused printing paper and dry plates
before the fumigation, although it is not definitely
known that they would have been injured by the gas.
The morning after the fumigation dead insects were
found lying everywhere about the building: flies had
dropped from the ceilings and windows, and mice had
come from their hiding-places and died.

11 For each fumigation one-tenth (o.i) of a gramme
of potassium cyanide was used for each cubic foot of
space in the building. All the connecting doors were
opened. Four stone jars were placed one at each end
of the building on the two floors. No exact measure-
ment was made of the strength and quantity of acid,
but an attempt was made to use about the same weight
of commercial sulphuric acid as of potassium cyanide.
The commercial acid was diluted by pouring it into
the water which was placed in the jars first. The
cyanide was then dropped into the mixture while still
hot and the building at once closed for the night. ' '

CHAPTER XVII
GRAINS AND OTHER SEEDS

N view of the fact that hydrocyanic acid gas is
being universally used as a fumigant for the
destruction of insects in grain and seeds stored
in various enclosures, it became necessary to
know how this gas would affect edible and germinating
properties of the grain. Conclusive and detailed
results were obtained by Dr. Charles O. Townsend,
now Pathologist in the U. S. Department of Agricul-
ture. The work was done in connection with the
Maryland State Horticultural Department while he
was State Pathologist. The methods employed in
these experiments consisted simply in placing the seeds
to be tested in air-tight chambers and then generating
the desired amount of gas. In the first experiments
air-tight boxes of several cubic feet capacity, such
as are used by nurserymen, were employed. In these
various experiments the gas was generated in the same
manner as for nursery stock. In later experiments
Dr. Townsend used large glass bell- jars. The jars were
so arranged that the gas could be generated and kept
within them for any length of time with the seeds.

The seeds used were mostly corn, wheat, beans and
clover. Occasionally other seeds were used, but those
mentioned were carried through all the experiments
and fairly represent the common grains and other seeds.
Some seeds under certain conditions seem to be more

178 FUMIGATION METHODS

sensitive to treatment t^an others, but the behavior in
general did not vary much. The strength of the gas
used varied from 0.003 °f a gramme per cubic foot to
1.45 grammes per cubic foot. In the first experi-
ment Dr. Townsend's obje<5l was to determine whether
the ordinary strength of gas used in fumigation
would be harmful to the seeds. In later experiments
he determined the maximum and minimum strength
of gas that seeds could resist under varying condi-
tions.

Time is an important factor in this work. Nursery
stock must be fumigated 30 to 45 minutes or longer
to destroy all insect life, but in the fumigation of build-
ings in which large bulks of grain are stored, time must
be allowed for the gas to penetrate the mass. During
this period the grain on the surface is exposed to the
influence of the gas from the time it is generated. To
determine the shortest and longest time required for
grain to respond to the influence of the various
strengths of gas under different conditions employed,
the exposures varied from one hour to one year.
Seeds were also fumigated under varying conditions,
some being used while perfectly dry in a dry chamber,
while others were used after being soaked in water,
and still others were soaked and placed in a moist
atmosphere filled with gas. After considering all the
facts Dr. Townsend's conclusions are concise, clear and
practical.

He found that seeds, whether in the dry or moist con-
dition, are capable of absorbing hydrocyanic acid gas
from the surrounding atmosphere, whether the amount
of gas in the atmosphere is large or small per cubic foot.

GRAINS AND OTHER SEEDS 179

The gas thus absorbed has a marked influence upon
the germination of the seeds and upon the subsequent
growth of the seedlings. In these experiments it was
found that some of the seeds were able to resist for
more than three hours the influence of the gas from
0.25 gramme of potassium cyanide per cubic foot, al-
though after three hours 50 per cent, of the seeds were
unable to germinate and the other half were held in
check for forty-eight hours beyond the usual time of
germination. However, the seeds that did germinate
produced seedlings that grew at the normal rate. If
the grains or seeds are dry, the influence of the gas is
far less marked than if they are moist, and the drier
they are, the less they are influenced by the gas.

It would seem, therefore, that the gas exerts its in-
fluence through the medium of the moisture contained
in the seeds and in the seedlings. Even in older plants
it is the more succulent parts that are most readily af-
fected by the gas. The seed-coats serve more or less
as a protection for the inner seed parts, and as soon as
the seedlings escape from the seed-coats they are more
seriously affected by the gas, and if the charge is suf-
ficiently strong the seedlings refuse to grow almost as
soon as they leave the seed-coats. Dry seeds are suf-
ficiently resistant to the influence of hydrocyanic acid
gas to be treated for several weeks with an atmosphere
saturated with the gas without destroying their vital-
ity. It would be impossible, however, to preserve
even dry seeds indefinitely in any strength of the gas,
since it eventually penetrates the dry seeds and im-
pairs and finally destroys the vitality of the seeds. If
the seeds are damp they are much more susceptible to

180 FUMIGATION METHODS

the influence of the ga», and should not remain more
than two or three hours in gas of sufficient strength to
destroy animal life.

Dry seeds. — Only a few experiments have been
performed along this line, but probably a sufficient
number to determine the point in question, viz.,
whether dry seeds treated with hydrocyanic acid gas
retain enough of the gas to make them injurious to
animal life. Grain was subjected to gas of different
strengths, and for longer or shorter periods of time,
varying from one to sixty days. Grains thus treated
were from time to time fed to mice that had been
caught without injury, and placed in glass cages so
that they could be observed constantly. The cages
were provided with an abundant supply of air and
water, and kept at ordinary normal temperature of the
laboratory where the mice had been living previous to
the beginning of the experiment. Occasionally the
mice began eating the grains as soon as they wrere
placed within reach, but, as a rule, several minutes to
several hours elapsed between the time the grains were
taken from the hydrocyanic acid gas and the time they
were eaten by the mice, thus giving time for any gas
that remained in contact with the seed or that had
penetrated the seed-coat to escape into the amosphere.

In one instance, for example, a mouse was fed one
dozen kernels of corn and three dozen grains of wheat
that had been for four and one-fourth days in an at-
mosphere containing gas from one gramme of potas-
sium cyanide per cubic foot. The mouse began eating
the grain at once, and at the end of twenty-four hours
had eaten the whole of five grains of corn and had

GRAINS AND OTHER SEEDS l8l

eaten the chit out of five other grains. It had also
eaten fourteen grains of wheat and had eaten the chit
of eleven others without injury. Several similar ex-
periments were carried through with like results.
Hence it seems safe to conclude that dry grains treated
for several days with hydrocyanic acid gas of sufficient
strength to destroy insect pests that may be in the
grain will in no way poison the grain, and it may there-
fore be used for food without injury.

Damp seeds. — The damp seeds were soaked for
twenty-four hours and then treated with gas in the
same manner as in the preceding experiments and were
kept in the gas for different periods of time varying
from several hours to several days in the different ex-
periments. Here, as in the germination experiments,
we find that moisture has a decided influence upon
the ability of the grains to absorb gas, i.e., after soak-
ing some corn and wheat for twenty-four hours in
water and then leaving for forty-eight hours in the gas
obtained from one gram of potasium cyanide per cubic
foot, a mouse in apparently good health was given
twelve grains of corn and thirty-six grains of wheat.
The mouse began eating at once and ate the chit out
of one kernel of corn and began eating a second ker-
nel when he suddenly became stupid and was unable
to walk without staggering. That the mouse was
hungry is evidenced by the fact that it began eating as
soon as the grain was placed in the cage and from the
fact that it had been given but little food on the pre-
ceding day for the purpose of having it hungry enough
to begin at once on the grain as soon as it was removed
from the gas. Although the mouse lived for several

1 82 FUMIGATION METHODS

hours, it eventually died apparently from the effects
of the small amount of grain eaten, as it did not eat
any more of either kernel of grain nor would it eat
cheese or any other material placed before it.

In general it was found that if the mice ate the
damp grain immediately after taking it from the gas
they became stupid and eventunlly died from the
effects. If, however, the grain was allowed to remain
for a time out of the gas before it was eaten, no ill
effects seemed to be produced, although the grain did
not seem to return to its normal condition, as it was
never eaten readily after it became perfectly dry.
When the mice could be induced to eat it, as they
were in several instances, it did not seem at all injuri-
ous. It may be concluded, therefore, that the fumi-
gation of dry grains with hydrocyanic acid gas does
not in any way injure the grain for food purposes.
And even if the grain is damp, it will not be made in-
jurious for food, if -it is allowed to air for a short time
after fumigating before it is prepared for use.

Summary. — In brief, Dr. Towsend has clearly
summed up the results of his work in the following
paragraphs:

Stored grains and other seeds may be fumigated with
hydrocyanic acid gas of required strength and for
sufficient time to insure the destruction of insect pests
without injury to the germinating quality of the seeds
and without rendering them injurious as foods.

Dry grains and other seeds may be fumigated with
the usual strength of hydrocyanic acid gas for several
days without in any way interfering with the germi-
nating property of the seeds.

GRAINS AND OTHER SEEDS 183

Dry grains and other seeds treated for several days
with hydrocyanic acid gas of any strength will not be
injured for food.

Dry grains and other seeds may be subjected for
several months to the influence of hydrocyanic acid gas
at the rate of one gramme or less of potassium cyanide
per cubic foot without entirely destroying the ability
of the seeds to germinate.

Dry grains and other seeds subjected to the influence
of hydrocyanic acid gas derived from one gramme of
potassium cyanide per cubic foot will lose their germi-
nating ability at the expiration of eight months, while
the same seeds subjected to the gas from one-third of a
gramme of potassium cyanide per cubic foot will
retain their vitality until the expiration of twelve
months.

Dry grains and other seeds subjected for from fifteen
to sixty days to the influence of hydrocyanic gas from
one-third to one gramme of potassium cyanide per
cubic foot will hasten germination and accelerate the
growth of the resulting seedlings. Although the
acceleration continues for several days it does not seem
to be of sufficient duration and degree to be of any
practical value.

Damp grains and other seeds are much more sensi-
tive to the influence of hydrocyanic acid gas than dry
seeds.

Grains and other seeds soaked twenty-four hours or
more will not germinate in gas stronger than three-
thousandths of a gramme of potassium cyanide per
cubic foot, whereas if the seeds are soaked but twelve
hours, they are able to germinate in an atmosphere

1 84 FUMIGATION METHODS

containing hydrocyanic^cid gas from fifty-thousandths
of a gramme of potassium cyanide per cubic foot and
in much less time than when soaked for twenty-four
hours.

Grains and other seeds soaked for twenty-four hours
and then left for seven days in an atmosphere of hydro-
cyanic acid gas will remain inactive while in the gas
and from seven to twelve days after removal, but will
eventually germinate to some extent if the strength of
gas used does not exceed fifty-thousandths of a gramme
of potassium cyanide per cubic foot, i.e. , hydrocyanic
acid gas is capable of holding seeds in an inactive state
for two weeks or longer without destroying their vital-
ity, even when the conditions are otherwise favorable
for germination.

Damp grains and other seeds treated with hydrocy-
anic acid gas of any strength even for short periods of
time should not be used for food until several hours
after removing from the gas. The effect of the gas
eventually passes off and the grain may be eaten with
safety, although long exposure to the gas seems to
render it unpalatable.

In the first experiments conducted by the writer,
where grain and manufactured products were stored,
the gas was generated at the rate of o. 10 to 0.12
gramme per cubic foot. Very satisfactory results were
secured, but further experiments showed that it was
better to use from 0.20 to 0.25 gramme per cubic foot
of space enclosed. It was found that a greater volume
of gas remained in the building for a longer time
where larger doses were used. At the same time no
deleterious effects were observed either in the manu-

GRAINS AND OTHER SEEDS 185

factured products or the grain in storage. Repeated
applications of this gas in mills, elevators, and other
enclosures with the 0.25 gramme formula has proven
that this is one of the most effective and satisfactory
remedies for the destruction of insedls and vermin in
such places now known.

-

CHAPTER XVIII
DIFFUSION OF HYDROCYANIC ACID VAPOR

I

N a recent report (twelfth) of the Delaware Agri-
cultural Experiment Station, Prof. Charles L<.
Penny gives the results of a careful series of
experiments to determine the diffusion of
hydrocyanic acid vapor in an enclosed space, from
which the following facts are abstracted or quoted: In
all the diffusion experiments, in both small boxes and
large rooms, a uniform charge of chemicals was used.
For each cubic foot of space to be filled with o. 2 gramme
potassium cyanide, 0.45 c. c. water, and 0.3 c. c. of 91
per cent, sulphuric acid.

In the box experiments the acid was allowed to
run into the cyanide previously dissolved in water.
In the room experiments the water and acid were
poured together in a two-gallon earthen vessel, into
which the cyanide was dropped. As the potassium
cyanide was on the average of 96.7 per cent, purity,
containing 40.14 per cent, hydrocyanic acid, it would
have furnished 0.08028 gramme of that acid per cubic
foot if all had been liberated. Professor Penny found,
as he expected, that a certain amount of hydrocyanic
acid always remained in solution in the generating
liquid, depending on the temperature and the time of
exposure of the latter. In the case of the box experi-
ments this residual hydrocyanic acid varied from 2 to
8 per cent, of the whole amount originally present, and

186

DIFFUSION OF HYDROCYANIC ACID VAPOR 187

after standing over night it was as little as 0.66 per
cent., averaging 4.71 per cent.; the particular amount
was determined for each experiment and was deducted
to determine the amount of actually liberated or avail-
able hydrocyanic acid vapor.

In the case of the room experiments the average
residual hydrocyanic acid was found to be 4.97 per
cent, of the whole amount; this was deducted in each
case to determine the liberated or available vapor.
Thus, at the temperature at which the experiments
were made, both with large and small quantities of
reagents, the proportion of acid and water used gave
about 95 per cent, of available vapor. This liberated
or available vapor on an average 0.07623 gramme per
cubic foot of space, called by Professor Penny the
"HCN," was taken as the basis of calculation to
determine the ratio of diffusion; in other words, that
amount found in a cubic foot would be called a diffusion
of loo per cent.

Quite as important as the average percentage of
diffusion, Professor Penny shows, is the average per-
centage of fluctuation. In such work absolute uni-
formity of conditions with the facilities available is
not attainable; hence repeated trials with conditions
apparently the same often give different results, some-
times widely different. As perfectly air-tight walls, both
of boxes and of the room, are difficult to secure, there
are varying conditions that make no two trials exactly
alike. Such discrepancies, although they cannot be
foreseen, may be explained by variations in the force
and direction of the wind, varying amounts of humidity
and the host of minor conditions that are never quite

1 88 FUMIGATION METHODS

the same, but yet influence the result. Hence, in
addition to the average diffusion, the fluctuation in
percentage between repeated trials is given. This
indicates the degree of constancy in the work.

It might be supposed, says the author, as pure
hydrocyanic acid is a liquid that boils at 80° F. , and
inasmuch as most practical applications of the acid
are made below that temperature, that ordinarily
but a small portion of the acid would vaporize, and
that this portion would diminish rapidly with a falling
temperature. Such, however, is not the case. The
proportion of the acid used in Professor Penny's experi-
ments, if it were all liberated, would amount in weight
and also in volume to only one five-hundredth part of
the air. As the vapor pressure of the acid is half
an atmosphere at 40° F. , it is clear that even in this
low temperature many times as much acid as could
ever be used (in fact, over two hundred times as much)
would still remain in the state of vapor. Hence the
condensation of the minute trace of hydrocyanic acid
that is ever used in practice would be impossible at any
natural temperature whatever. The " surf ace con-
densation," referred to later by Professor Penny, is the
solution of the acid in the film of condensed moisture
adherent to walls and other surfaces.

The results. — The results summed up below were
obtained by Professor Penny with a box of sixty cubic
feet capacity, of which the horizontal dimensions were
8 feet by 3 feet and the vertical depth 2^ feet. The
box had double wooden walls, with paper between
them, and made as nearly air-tight as possible. The
generator and the point at which the sample was

DIFFUSION OF HYDROCYANIC ACID VAPOR 189

taken, or the " intake," were in one case at the same
end of the box, in the other case at opposite ends.
The ' ' diffusion time ' ' was the time elapsed between
the liberation of the vapor and the taking of the
sample.

"It appears," says Professor Penny, "from the
results obtained that immediately after the generation
of the hydrocyanic acid, as would be expected, there
is an excess of it around the generator, that this excess
disappears within two minutes, leaving but one-third
the normal quantity at that point, and that at the oppo-
site end there is a still greater excess, viz., two and
one-half times the normal amount ; that this latter
excess in turn rapidly falls and the vapor around the
generator again increases in amount, so that there is a
tendency toward equilibrium, though considerably
over twenty minutes would be required to approximate
perfect equilibrium. Hence, for the duration of a
practical trial by far the greater amount of vapor
would be in the end of the box farthest from the gen-
erator.

' ' The fluctuations between repeated trials under
similar circumstances are relatively slight ; that is,
uniformity is the rule. What is found true in one
instance is, with due regard to the general character
of the work which precludes extreme accuracy, sub-
stantially true in similar instances. This may be
attributable in part to the double walled and paper-
lined box, which reduced the influence of air currents
to a minimum."

Diffusion in box. — "The following results in the
second experiment were obtained with a box of 29

190 FUMIGATION METHODS

cubic feet capacity, of which the horizontal dimensions
were 13^ feet by i^ feet and the vertical i}^ feet.
The experiments covered five different cases, and it
appears first that there is less uniformity than with
the box of 60 cubic feet. This may be due, and prob-
ably is in part, to the structure of the two boxes, the
former having rawhide roofing paper sides and the
latter double sides with paper lining. Hence in the
case of the box under discussion outside disturbing
influences may have been felt to a greater degree.

' ' With the intake at the same end of the box as
the generator, after three minutes' diffusion time there
appeared in a single instance a deficit of acid vapor as
compared with the normal, in two other instances a
considerable excess. The extreme fluctuations found
show forcibly the inconstancy of spontaneous diffusion,
especially with this arrangement and after a short
interval of time. With the generator at the middle of
the box and the intake at the end there is greater uni-
formity and after ten minutes a considerable deficit,
which deficit remains practically the same for a half
hour ; the amount of vapor then gradually diminishes,
doubtless through leakage. It appears then that of
these two arrangements, viz., the generator in one
case at the end of the box and again in the middle,
the latter gives more uniform results and also a more
even distribution of the acid vapor. This is, perhaps,
what would be expected, but it must be noted that
even in the latter case the quantity of vapor in one
instance is double what it is in two other instances.

"/« summary, then, be it noted of these cases of
spontaneous diffusion that within a half hour of diffu-

DIFFUSION OF HYDROCYANIC ACID VAPOR 1 91

sion time the amount of hydrocyanic acid vapor at a
given point may be as little as 23 per cent, of the
normal and as high as 272 per cent., or, with the same
quantity of reagents per cubic foot and in the same
box, at one point there may be twelve times as much
acid vapor as at another. Of course this inequality
would not continue long, but it does exist in certain
cases for a time. Hence it must be apparent, if we
rely on spontaneous diffusion, that the amount of
cyanide used per cubic foot is no guarantee on the one
hand of sufficient acid vapor to do the work, nor, on
the other, of too little to injure plants."

Mechanical mixer. — In these tests a mechanical
mixer was used in the box of twenty-nine cubic feet
capacity. This device consisted of a fan on a hori-
zontal axis which passed through the sides of the box
and was turned by means of a crank from the outside.
The results showed a remarkable uniformity for work
of this general character, varying from 68 per cent, to
74 per cent, of the normal. The average is 72 per
cent. , and this may be taken as the true measure of
efficiency under these conditions, i.e., with a similar
size and proportion of box and equal loss from leakage.
As about 5 per cent, of the total hydrocyanic acid re-
mains in solution in the generator, and of the 95 per
cent, evolved 72 per cent, is uniformly diffused, it would
follow that about 68 per cent, of the total hydrocyanic
acid gas originally present in the cyanide, or approxi-
mately two- thirds, becomes efficient by uniform diffu-
sion throughout the box. Of the remaining 32 per
cent. , aside from the 5 per cent, left in the generator,
the balance, 27 per cent., is to be accounted for by

IQ2 FUMIGATION METHODS

leakage and by surface condensation on the walls of
the box, or rather by solution in the film of moisture
adherent to the walls.

Effeft of moisture on foliage. — "Experiments
were designed to show the effect of moisture adherent
to foliage. A quantity of maple and cherry leaves
were held under a hydrant, then shaken to remove the
excess of water and placed in the diffusion box. The
amount of adherent water was about two and three-
quarter pounds. In each trial a fresh lot of leaves
was used, and a mechanical mixer or fan was used to
complete the diffusion. Two trials showed an average
of 54 per cent, as compared with 72 per cent, obtained
without the wet leaves, or, with the wet leaves, just
three-fourths as much acid vapor is diffused through
the atmosphere of the box as without them. This is
significant asv indicating the effect of wet foliage. The
amount of acid vapor available for killing insects is
diminished and the amount acting directly on the
plants is increased." Thus the necessity of having
plants either in the nursery or orchard as dry as pos-
sible.

Absorbent effect of fresh earth. — "In this experi-
ment the bottom of the 2g-cubic foot box was removed
and the box was placed over fresh soil; the soil was
thoroughly packed or tamped around the edges. The
surface soil thus exposed was i^ x 13^ feet, or about
20 square feet. The mechanical mixer was used, as
noted above. The two trials, with closely concordant
results, show an average of 44.5 per cent, of the normal
amount of acid vapor as compared with 72 per cent, of

DIFFUSION OF HYDROCYANIC ACID VAPOR 193

soil. Hence, in a box resting on soil, about 62 per
cent, as much acid vapor is available as in a closed
box. It would seem necessary, then, in work of this
sort over soil to use nearly twice as much cyanide and
other reagents as in a closed box."

Diffusion in large room. — " Bxperiments were made
in a rectangular room of which the horizontal dimen-
sions were 20 feet 9 inches by 19 feet i inch, and the
height 10 feet n inches, and which included 4,332
cubic feet. The walls and ceiling were plastered and
the floor was of boards ; there were four windows and
three doors. The crevices were stopped as far as
possible, but necessarily the room was far from air-
tight. Samples of air were taken simultaneously from
three different points within the room. The position
of two of these points and also of the generator was
changed several times in order to study the diffusion
in different places. The generator was a glazed stone-
ware vessel 8 inches in diameter and 1 5 inches high.
The charge of reagents in the case of the room-experi-
ments was the same per cubic foot as in the case of the
box-experiments, in the former amounting to 866.5
grammes cyanide, 1,300 c. c. of concentrated sulfuric
acid, and 1,950 c. c. of water. The water was poured
into the generator, the acid was then poured into the
water, and immediately thereafter the cyanide, wrap-
ped in paper, was dropped by means of a string, into
the acid mixture."

General results. — "After ten minutes of diffusion
time, with the generator in one corner on the floor, the
amount of vapor in the center of the room at the ceiling

194 FUMIGATION METHODS

was 'about normal, with a trifling excess. On the floor
by the side of the generator there was none at all, or
only a mere trace. On the floor diagonally opposite
to the generator it averages, with rather wide fluctua-
tions, 73 per cent, of the normal. After 20 minutes
the center at the ceiling showed a trifling loss, the
point on the floor next to the generator showed 27 per
cent, of the normal, and the point on the floor in the
opposite corner showed 94 per cent. After 30 minutes
these figures were not greatly changed for the first and
the last, while for the second point, that next to the
generator, the vapor is 51 per cent, of the normal,
nearly double its amount after 20 minutes. After an
hour the diffusion is practically complete, the amount
of vapor at the three points being 52, 44 and 44 per
cent, of the normal, while after four hours and a half
it is 25, 24 and 21 per cent., respectively.

* ' It is apparent that there is a rapid loss in the total
amount of acid vapor from the room as a whole. This
loss cannot be easily estimated until there is practically
complete diffusion, as the average of the three points
would not necessarily, nor even probably, give the
average for the whole room. It would seem, then,
after one hour there is a trifle less than one-half of the
normal amount of acid vapor in the room, and after
four and one-half hours a trifle less than one-quarter.
The rate of loss is probably greater through a plastered
wall than through one of boards, and it would doubt-
less require a special air-tight construction of a room
to reduce this rate very considerably. Hence, the con-
stant loss must be borne in mind in considering the
completeness of the diffusion.

DIFFUSION OF HYDROCYANIC ACID VAPOR 195

"It is clear from the results that the acid vapor
rises from the generator vertically, follows the ceiling,
descends on the opposite side of the room and com-
pletes the circuit by returning to the generator. Thus
the point immediately at the side of the generator is
the last to receive any vapor, while the opposite point
on the floor quickly receives almost its normal amount.
This is what might be expected from the shape of the
generator, an open jar, 15 inches high and 8 inches
in diameter, which has the effect of projecting the
charge of vapor directly upward; and, furthermore,
while the density of hydrocyanic acid vapor, a very
little less than that of air, is not small enough to cause
it to rise rapidly, yet its expansion by the heat of the
reaction is considerable. Hence the tendency of the
acid vapor to ascend is, for several reasons, the natural
thing to expect, and to secure rapid diffusion a counter-
acting cause must be set to work. At the moment of
generation the vapor, or, rather, the accompanying con-
densed steam, may be actually seen to take the course
that has been described, though naturally but for a
minute or two.

' ' When the generator is moved to the center of the
floor, the intake remaining in the same place, after ten
minutes there is found 75 and 88 per cent, in the two
corners and 123 per cent, in the center of the ceiling.
This is in general agreement with what has already
been noted, as in this case the two corners are arranged
alike in reference to the generator, and, as before, the
greater part of the acid vapor is at the ceiling.

' ' Where the generator is in the corner of the room
and the three intakes are in a vertical line in the

196 FUMIGATION METHODS

center of the room, one* near the ceiling, one near the
floor, and one midway between, after twenty minutes
practically the same amount of vapor on an average is
found at the ceiling and at the middle point, whereas
the space near the floor shows about one-third as much
as the other two.

"Where the generator is covered with a box
that extends on all sides to the floor, the effect is
to throw the vapor down to the floor. The results
show a greater amount there than in the preceding
arrangement. This device is quite inadequate to
secure an even distribution of vapor.

' ' In this test the generator was placed two feet
from a side wall at the middle point, and provided with
a horizontal distributing tube. The intakes were in a
vertical line in the center of the room. The effect of
this simple arrangement was surprising. After ten
minutes there was practically a uniform distribution of
acid vapor, at least in so far as the three points of
sampling may be taken as typical, and they seem to be
fairly representative. After twenty minutes there was
found to be but a slight change, well within the limits
of fluctuation in work of this sort. This simple device,
designed by Professor Sanderson, is shown in Chapter
XII. The acid vapor is distributed immediately with
surprising uniformity. Thus has been solved perfectly
the difficulty of securing an even and speedy diffusion,
and that, too, in a very simple and practicable way.

; ' These results may be taken as showing fairly well
how much of the hydrocyanic acid can be accounted
for, and that is 93 per cent, of what is actually evolved,
or about 88 per cent, of the total amount contained in

DIFFUSION OF HYDROCYANIC ACID VAPOR 1 97

the cyanide. Thus, of the total amount of hydro-
cyanic acid about 5 percent, remains in the generator,
88 per cent, is diffused, and 7 per cent, must be
charged to leakage or surface condensation on the
walls of the room. In the experiments with the box
it was estimated that only 68 per cent, of the total
hydrocyanic vapor is actually efficient, the remainder
being lost in the ways suggested. This greater loss
with the smaller box is just what we should expect,
for the relative amount of wall surface as compared
with the cubic contents is much greater. ' '

CHAPTER XIX
RECENT WORK WITH HYDROCYANIC ACID GAS

UCCESSFUL A PPLI CATION IN ENGLAND. — The black
currant bud-mite and the mealy bug are among
the most dangerous and elusive enemies of
the greenhouse and garden in England. So
severe have been the losses by the former that the
currant industry is in a critical state. One grower is
reported as having said recently that his crop had
fallen from £ 1,400 a year to practically nothing on
account of the mite. The latter pest is found gener-
ally in the vinery. The application of sprays and
washes have not been successful in keeping either pest
in check.

In a recent paper by H. H. Cousins, in the Jour-
nal of the Agricultural College, at Wye, Kent (Vol.
XXV.), he reports successful results where hydro-
cyanic acid gas was used. Speaking of his experi-
ments, he says the spread of the black currant bud-mite
is clearly due in the first place to the propagation by
cuttings from infested stock. Buds of apparently
normal dimensions frequently contain a few mites
capable of indefinite increase. In the case of the
Baldwin currant it is most difficult to find a shoot free
from mites, even when the buds appear quite healthy.
Diseased stock undoubtedly spreads the infection by
the mechanical distribution of the mites on the clothes

iq8

RECENT WORK WITH HYDROCYANIC ACID GAS 1 99

of the men engaged in hoeing, or through the agency
of the wind or of birds.

Preliminary experiments indicate that at least forty
minutes' exposure to the cyanide fumes was necessary
to ensure the complete destruction of the mites.
Shorter periods were apparently successful at a first
inspection, but a further examination showed that
many individuals recovered after twenty- four hours.
Doses of cyanide varying from 0.05 gramme to 0.4
gramme per cubic foot were tested. A minimum of
0.2 gramme per cubic foot was satisfactory. A
stronger dose than 0.3 is not desirable.

Cuttings and young bushes. — About 2,000 diseased
bushes intended for planting were treated January 3d
as follows : They were tied in bundles and placed in a
heap on the ground. Four hurdles were arranged as
a support, and the whole covered with a waterproof
cloth. A small vessel was placed on the ground in
the center of the heap of bushes. One htindred cubic
centimeters of water (about 4 ounces) were added,
followed by an equal volume of strong sulphuric acid.
Thirty-six grammes (about i^ ounces) of commercial
98 per cent, potassium cyanide was wrapped in thin
blotting-paper and dropped cautiously into the vessel
of acid and water. The hand was at once withdrawn
and the canvas carefully pressed down all round with
lengths of timber. After one hour the cloth was
removed and the operation was complete.

Mr. Theobald conducted a systematic microscopic
analysis of the treated buds, and established the fact
that this treatment had destroyed all the mites. The
bushes were planted out in disease-free soil and were

20O FUMIGATION METHODS

under constant inspection. A fortnight later a second
batch of young bushes was similarly treated and with
identically good results.

The cost of chemicals is only about a penny per
thousand bushes and the labor involved trifling. All
cuttings should be fumigated before being set. Black
currants so quickly come to a good bearing size that
it would be well to grub a badly infested plantation
and start afresh with fumigated young stock.

To the above report A. D. Hall, the principal of
the college, adds the following: "I am not by any
means disposed at present to definitely recommend the
hydrocyanic process other than by way of experiment,
and until we have seen more results I should prefer to
say nothing. If the process recommended be carried
out in the winter, when the temperature is low and
the bushes in a dormant state, no injury whatever is
done to the plants. The real difficulty lies in the eggs
of the mite ; it seems to be always laying eggs, except
perhaps in the very coldest weather ; and though we
are now sure the adult mite is killed by the treatment
we are still doubtful about the eggs. The treatment
of large bushes in situ has failed on the whole."

Mealy bug in vineries and conservatories. — Through
the kindness of Colonel Ready, of Goudhurst, and Mr.
Hammond, of Ramsgate, Mr. Cousins was enabled to
try the effect of cyanide fumigation under a variety of
conditions. Three vineries, A, B, and C, were twice
treated, as was also a large conservatory. In each
case the attack of the mealy bug was severe.

Vinery A. — The capacity of this house was 3,430
cubic feet. It contained an early variety and was

RECENT WORK WITH HYDROCYANIC ACID GAS 2OI

treated when vines were in full bloom with the follow-
ing : Cyanide, 18 ounces; acid, 27 fluid ounces; i
quart of water. The temperature was 60° F. Time
of exposure was half an hour. The work was done
after sunset. The mealy bug was destroyed, foliage
unhurt, but three-quarters of the bloom was injured.
A few mealy bugs appeared at the close of the season,
after the grapes had been gathered. A second fumi-
gation was therefore decided upon and the results were
satisfactory.

Vinery B had a capacity of 3,825 cubic feet and
contained a late variety. It was treated before vines
bloomed with the following dose: Cyanide, 27 ounces;
acid, 40 ounces; water, 60 ounces. The application
was made after sunset and exposed three hours at a
temperature 60° F. The mealy bug was destroyed
and there was no injury to vines. A few insects ap-
peared in the autumn and a second fumigation was
given, with the same success as in the previous case.

Vinery C had a capacity of 1,990 cubit feet and
was planted with an early variety. It was treated
when the grapes were the size of peas with the follow-
ing chemicals : Cyanide, 6 ounces; acid, 9 ounces;
water, 15 ounces. The temperature was 65° F. ;
weather very sultry at the time. Time of exposure
was forty minutes and application was made at 3
P.M. The grapes were browned and killed, while the
foliage was uninjured. The mealy bug was de-
stroyed. The vinery was kept on the cool side, plenty
of air given, and splendid growth and promise of fruit
for next year was obtained. A few mealy bugs ap-
peared in October. Fumigation was repeated. All

202 FUMIGATION METHODS

the bugs were destroyed. The season had so far ad-
vanced, however, that the eggs were to be found on the
shoots. Painting the rods with the winter alkali wash
in the spring and a fumigation before the bloom
appears to have been decided upon.

A conservatory of 300 cubic feet, containing mixed
flowers and ornamental plants and ferns, etc. , infested
with aphis and mealy bug was fumigated after sunset
with cyanide, 8 ounces; acid, 12 ounces; water, 20
ounces. The temperature was 50° F. Time of ex-
posure was three-quarters of an hour, with complete
success. There was no injury to maidenhair fern
or any of the plants under treatment. The cost did
not exceed i shilling.

A greenhouse of 2,000 cubic feet, containing chrys-
anthemums in full bloom severely infested with green-
fly, was treated one hour before sunset with cyanide,
3^ ounces (0.05 gramme per cubic foot) ; acid, 5
ounces ; water, 9 ounces. The temperature was 52°
F. and the time of exposure was 25 minutes. Every
aphis was killed, also slugs, flies, wasps and butter-
flies. A toad was uninjured. Not a petal or leaf was
hurt.

Conclusions. — Mr. Cousins is of the opinion that
these experiments should encourage practical men to
give cyanide fumigation a thorough trial for such
pests as are beyond ordinary treatment. For green-
house work he recommends the following : If the
house be under 10,000 cubic feet one vessel will suffice;
if over, provide a vessel for each 10,000 cubic feet.
Arrange the ventilators so that they can be opened

RECENT WORK WITH HYDROCYANIC ACID GAS 203

from without. The foliage of the plants should be
dry. A temperature not exceeding 60° F. and prefer-
ably of 50° F. is desirable. Above 60° F. there is
risk of injury to the foliage.

For mealy bug, 3 ounces cyanide, 5 ounces acid,
15 ounces water per 1,000 cubic feet, either before the
vines bloom, or when grapes are coloring, or after the
crop has been gathered. At either of these stages no
harm results to either foliage or fruit. Avoid fumi-
gation when the vines are in bloom, or before the
grapes have commenced to ripen.

For ordinary greenhouse pests, such as aphis,
dolphin, whitefly, slugs, woodlice, red-spider, and
caterpillars, a dose not exceeding 1 24 to 2 ounces cya-
nide, 4 ounces acid, 7 ounces water per 1,000 cubic
feet, has been found satisfactory in England. For a
detailed, account of greenhouse fumigation see Chap-
ter XIV.

Use in New South Wales. — In the center of the
citrus-growing belt of New South Wales, W. J. Allen,
an expert of the government, has conducted some very
satisfactory experiments with hydrocyanic acid gas in
cooperation with the Glenorie Progress Association.
Various sprays were tried at the same time and com-
pared with the gas treatment. In his report of the
practical tests, printed in Vol. XII. of the Agri-
cultural Gazette of New South Wales (see also Agri-
cultural Gazette for August, 1899, an^ July, 1900), Mr.
Allen says:

The fumigation of the trees with hydrocyanic acid
gas gave the best results of all. This was conceded

2O4

FUMIGATION METHODS

by all growers who Allowed up the experiments.
The cost of treatment was the same as that of the blue
oil emulsion and slightly in excess of the resin work.

1

FIG. 75 — FUMIGATING IN G. TURNER S ORCHARD AT
GLENORIE, NEW SOUTH WALES. (AFTER ALLEN)

The fumigated trees made a better growth than those
in the same orchard not treated.

Several prominent growers requested Mr. Allen to
fumigate one or two badly infested trees in their
orchards, and, by the way of experiment, wished him
to give the trees an extra charge. They wanted to
make sure of killing the scale and see also the effect on

206 FUMIGATION METHODS

the tree. The trees were treated in the hottest part of
the day. This, added to the overcharge of cyanide,
caused many of the leaves to fall; yet it had little or
no effect on the fruit, and all the scales were killed,
Two-thirds of the dose would have been quite sufficient
to have cleaned the trees.

L,emons and mandarins stand the fumigation much
better than the orange. Taking two trees of equal
size and treating them with the same charge, while
the mandarin would not show any ill effect, the orange
tree would lose a few of its leaves. Mr. Allen, there-
fore, recommends always treating the latter at night
or on cool and dull days. The night treatment appears
to be the best, as a charge which would in the day-
time remove leaves, and, perhaps, burn the tender
parts of the twigs, would have no detrimental effect
where the work was performed at night. He thinks
that lemons and mandarins can be treated with very
good results during the daytime, except on very hot
days.

When Mr. Allen first commenced his fumigating
experiments in New South Wales the price of tents
was so high as to make it appear to growers that this
method of treating trees was quite out of the reach of
the average fruit-grower ; but several large growers,
rather than pay a high price for material, bought
strong calico and sail-cloth, and made tents from these
materials, and these, after a fair trial, have stood the
test quite as well as the more expensive duck tents,
and cost only about one-quarter as much.

The cost of material for tents made of sail-cloth 6
feet wide, estimated by Mr. Allen, is as follows for the

FIG. 77 — AVERAGE SPECIMEN OF FRUIT FROM A FUMIGATED
TREE IN NEW SOUTH WALES ORCHARD. (AFTER ALLEN)

FIG. 78 — AVERAGE SPECIMEN OF FRUIT FROM A TREE IN

SAME ORCHARD AS ABOVE, NOT FUMIGATED

(AFTER ALLEN)

20% FUMIGATION METHODS

different sizes : Tents 1^5 feet high, 24 feet in circum-
ference, require 16 yards of sail-cloth 6 feet wide,
which, at is. 3^. per yard, will cost £i\ tents 18 feet
high, 36 feet in circumference, require 30 yards of sail-
cloth 6 feet wide, which, at is. $d. per yard, will cost
£i ijs. 6d.

He says these are two of the most useful large-
sized tents for general use. The former is quite large
enough to cover trees 10 feet high and 8 feet in diam-
eter, while the latter is large enough to cover trees 1 3
feet high and 10 to 12 feet in diameter. If larger trees
are to be fumigated it is best to have octagonal sheets,
sizes either 41 x 41 or 50 x 50. A sheet is always
much easier to put over the tree than a tent where
large trees are being handled. The price of making
the tents is not given, as any person having a sewing-
machine can sew them together. To make the former
tent the material is cut in two. Find the center of
each length, and from this point measure back 3 feet
on opposite sides, draw a line diagonally across from
one point to the other, and cut as marked. After cut-
ting the two pieces can be sewn together. For the
large-sized tent, the 30 yards must be cut in three
pieces of 10 yards each, which should be cut again in
an exactly similar manner to the smaller-sized tent
and sewn together. Great care must always be taken
to keep the tents perfectly air-tight.

Good results. — The outcome was very gratifying,
and Mr. Allen says : ' ' I feel quite safe in saying that
by the autumn of 1901 there will be over a thousand
tents in use in New South Wales, with the result that
there will be more clean and better fruit for export

RECENT WORK WITH HYDROCYANIC ACID GAS 2OQ

and home consumption, and more healthy and vigor-
ous trees found in our fruit-growing districts. In
most cases the fumigation was successful wherever
experiments were conducted, and there can be no bet-
ter proof than that the growers are adopting this
method of destroying scales more and more as they
become acquainted with its advantages. ' '

Various materials have been used for making tents.
Mr. Allen thinks that tents made of sail-cloth will be
found durable and economical. We reproduce here-
with the table, compiled by Mr. Allen, for the various
amounts of chemicals to be used in orchards in New
South Wales.

FUMIGATION TABLE FOR NEW SOUTH WAI.ES
ORCHARDS

43
54
65
85
101
118
146
170
195
232
265
298

432
437
492
547
601
540
608
675
743
810

735

817

1,062 9
1,144

778

875

972

1,069

1,168

1,264

1,361

1,458

947

1,141
1,255
1,369
1,481
1,597
1,711
1,050

15

2IO

FUMIGATION METHODS

AXA82T8 FUMIGATION TABLE FOR NEW SOUTH WAIVES
ORCHARDS —Continued

L

v

1

^

W

1

•1

$

|

j.

f

3

C

t

Q

!§i

*

Q

^

3

5

fee

<L

8

^

**2

2

5

a

*

^

jjj

s

|

to

^

oz.

oz.

02".

OZ.

oz.

oz.

14

9

,191

6

6

18

18

17

3,718

18J4

55

14

10

,323

61^

19

18

18

3,937

19/4

19)4

58

14

11

,455

7)4

7)4

21

18

19

4,156

2014

20J4

61

14

12

,587

7%

7%

22

18

20

4,374

21%

21%

C5

14

13

,720

8)4

8J^

24

18

21

4,593

22%

22%.

68

14

14

,852

9)4

9)4

27

18

22

4,812

24

24

72

14

15

,984

9^4

9%

28

18

23

5,030

25

25

75

14

16

2,116

io)4

30

18

24

5,249

26

26

78

15

8

1,215

6

6

18

19

13

3,168

46

15

9

1.367

6%

654

19

19

14

3,412

17

17

51

15

10

1.519

7)4

7^6

22

19

15

3,656

18

18

54

15
15

11
12

1,671
1,823

9

8M

24
27

19
19

16

17

3,899
4,143

20U

57
60

15

13

1,975

9%

9%

27

19

18

4,387

21 8

%\y>

64

15

14

2,127

10J4

31

19

19

4,630

23

23

69

15

15

2,279

ii)4

11)4

33

19

20

4,874

24

24

72

15

16

2,430

12

12

36

19

21

5,118

25

25

75

15

17

2,582

12^4

12%

37

19

22

5,362

26J4

26J4

78

15

18

2,734

13J^

13)4

40

19

23

5,605

28

28

84

15

19

2,886

14^4

14^4

42

19

24

5,849

29

29

87

15

20

3,038

15

15

45

20

13

3,512

17^

52

16

10

1,728

8}^

24

20

14

3,782

18J4

18)4

55

16

11

1,901

9J/2

9)4

28

20

15

4,053

20

20

60

16

12

2.074

10*4

10)4

30

20

16

4,323

63

16

13

2,247

11

11

33

20

17

4.593

22%

22%

67

16

14

2,420

12

12

36

20

18

4,863

24

24

72

16
16

15
16

2,492
2,765

18%

13%

37
40

20
20

19
20

5,133
5,404

^

25)4
27

75

81

16

17

2,938

14J4

43

20

21

5,674

28

28

84

16

18

3,111

15)4

i§y>

46

20

22

5,944

29^

29)4

88

16

19

3,284

16)4

16J4

48

20

23

6,214

31

31

93

16

20

3,456

17J4

1714

51

20

24

6,484

32

32

96

16

21

3,629

18

18

54

21

14

4,168

20J4

60

16

22

3,802

19

19

57

21

15

4,466

22

22

66

17

12

2,341

11*4

H)4

34

21

16

4,763

23)4

69

17

13

2,536

12}^

12)4

37

21

17

5,061

25 2

25

75

17

14

2,731

13}4

13J4

40

21

18

5,359

26J4

26)4

78

17

15

2,926

14J4

14)4

43

21

19

5,657

28

28

84

17

16

3,122

151^

15/4

46

21

20

5,954

29^

29)4

88

17

17

3,317

16^

16V«j

49

21

21

6,252

31

31

93

17

18

3,512

17)4

17)4

52

21

22

6,550

32J4

32)4

97

17

19

3,707

18)4

18)4

55

21

23

6,847

34

34

102

17

20

3,901

19/4

58

21

24

7,145

3514

35)4

106

17

21

4.096

20j|

20 J4

60

21

25

7,443

37

37

111

17

22

4,291

21)4

21 J4

63

22

15

4.901

24J4

24)4

73

18

12

2,625

13

13

39

22

16

5,228

26

26

78

18

13

2,843

14

14

42

22

17

5,555

27^

27)^

82

18

14

3,062

15^4

1514

45

22

18

5,881

29

29

87

18

15

3,281

16/4

16J4

48

22

19

6,208

31

31

93

18

16

3,500

™

17%

52

22

20

6,535

32J4

32)4

97

RECENT WORK WITH HYDROCYANIC ACID GAS 211

AI^EN'S FUMIGATION TABLE FOR NEW SOUTH WAIVES
ORCHARDS.— Continued

23

7,188
7,515
7,842
8,168
8,495
5,357
5,714
6,071

oz.
34

40^
42

oz.
34

8*

30

oz.
102
106
112
117
121
126
79
85
90

6.785
7,142
7,500

7,857
8,214
8,571

oz.
32

86

41
4214

41

oz.

96
100
106
112
117
123
127
133
138

As a final caution, Mr. Allen says the full height
and width of the tree should be taken after the tent is
in place. Give a full charge of chemicals; it is better
to give a fraction of an ounce too much than too little.
Especial attention is called to Fig. 76, reproduced from
Mr. Allen's report. For full directions for making
and applying the gas, see Chapters II. and V. to X.,
inclusive.

Orchard work in Cape Colony, South Africa. — The
fumigation of orchards in Cape Colony is largely due
to the work of Prof. Charles P. Lounsbury, the Gov-
ernment Entomologist. The methods followed are
very similar to those used in California. The condi-
tions, however, governing the citrus industry of
southern California are somewhat different from
those found in Cape Colony. In California the black
scale is one of the principal pests against which fumi-
gation is conducted. This insect is practically un-
known to the colonial fruit growers, and where it does
exist it is kept in check by natural enemies. In point

212 FUMIGATION METHODS

of prominence, the red»scale ranks next to the black
scale in California. The red scale is also familiar to
fruit growers in the colonial orchards. Considering all
things, Professor Lounsbury is of the opinion that
fumigation conducted by the contract system would
be more advantageous to the colony than that done by
local organizations. There are only a few slight dif-
ferences in the methods of operating and handling
sheet tents. The derrick-poles used in the colonial
orchards for manipulating the tents are very much the
same as those employed in California. The dome-
shaped covers, known as bell tents, are used.

In a recent circular Professor Lounsbury makes the
following statement : ' ' Californians have demonstrated
that they can grow citrus fruits at a profit, in spite of
the heavy expense of fumigation. They fully realize
that they may have to keep fumigating for an in-
definite time. Their hope is, as ours, that efficient
natural enemies of the scale insects will be found in
the future. For South African fumigators it is espe-
cially recommended that changing poles be adopted for
small sheets. A few colonial parties have fumigated
for the white peach scale, Diaspis amygdali, and con-
sider the remedy economical and satisfactory. If light
weight sheets, handled with changing poles, were
used it is probable that the gas treatment for this scale
would become popular with a large number of our
fruit growers. ' '

New experiments at New York Agricultural Exper-
iment Station. — Some timely and practical work has
been recently completed at the New York Agricultural
Experiment Station by Prof. V. H. Lowe, the entomol-

RECKNT WORK WITH HYDROCYANIC ACID GAS 213

ogist. Through the courtesy of Director W. H. Jor-
dan, the writer secured the following summary of the
experiments.

In regard to these tests, Professor Lowe says :
' ' Our work consisted principally of experiments in the
orchard and with bud-sticks. The former were mainly
for the purpose of determining the strength of gas re-
quired to kill the scale during the winter and spring,
and incidentally the effect of the gas upon the trees,
and the latter to determine the effect of the gas at dif-
ferent strengths upon fruit buds. The experiments
in the orchard were divided into two series, as shown
by the following summaries :

WINTER TREATMENT

Trees fumigated December 13-24; weather cloudy

TREES

Strength
of gas

Time of
exposure

Results

6 pli

8

8

7
7

,„

1
1

im
ach

0.18 gran
0.18
0.25
0.25
0.30
0.30
0.18
0.18
0.30
0.30

ime

Hho

M

1

Yl
M

ur

Scales not killed; trees uninjured
Many live scales found; trees uninjured

Scales dead; trees uninjured

Scales not killed; trees uninjured
Tree dead

Trees f-u

SPRING EXPERIMENT

igatedjune 6-8 and June 16-24; weather cloudy

TREES

Strength
of gas

Time of
exposure

Results

4 plum

0.18 gramme

J^3 hour

Scales dead; trees uninjured

0.18 '

^

i

44 *4 44 It

87

025

ri

•

Scales dead ; trees uninjured, except

three trees, which showed slight in-

I

025

,

i

jury to foliage
Scales dead; foliage slightly injured

2

0.30 '

M

1

Foliage slightly injured

2

0.30

i

214 FUMIGATION METHODS

' ' From this summary it will be noticed that the gas
at o.i 8 and 0.25 gramme had little or no effect upon
the scale when the fumigating was done in the
winter; but that 0.30 gramme was strong enough to
kill the scales. Also that the spring treatment resulted
in killing the scales with the gas at o. 18 gramme and
only one-half hour exposure. All of the plum trees
treated were European varieties, and both plums and
peaches were healthy, vigorous trees. We used the
box fumigator shown at Figs. 43 and 81 in all cases.
Fig. 8 1 shows our improved method of fastening the
door on our fumigator.

' ' All of the trees were badly infested with the
scale. Where the term ' scales dead ' is used it
means that after very careful search at various times
during the summer following the experiment no live
scales could be found. The statement that the trees
were uninjured means that there was no effect on the
foliage and fruit buds.

" The buds included in the fumigation experiment
were of the following varieties : Apples — Jonathan,
Fall Pippin, Oldenburg, Ben Davis, Fameuse, and
Transcendant. Cherries — May Duke, Windsor, and
Early Richmond. Pears — Anjou, Bartlett, Seckel, and
Kieffer. Peaches — Elberta, Early Crawford, Blenheim,
Early Rivers, Beersmock, and Alexander. Plums —
Italian Prune, Reine Claude, Bradshaw, Shropshire
Damson, Burbank, Yellow Spanish, Yellow Egg, Lom-
bard, and De Soto.

' ' The buds were fumigated in a small box made
especially for the purpose. The gas was used at the
following strengths: o. 18, 0.22, and 0.30 gramme.

FIG. 79 — IMPROVED METHOD OF FASTENING THE DOOR
OF THE LOWE BOX FUMIGATOR

2l6 FUMIGATION METHODS

The exposure in each case was one -half hour and one
hour. The bud sticks were divided into lots, so that
each variety received the maximum and minimum ex-
posures of the various strengths of gas. Our bulletin
contains a number of tables showing the percentage in
each case of the buds that set, and comparisons are
made with checks.

" In all, 4,483 buds wrere treated, of which 78 per
cent. set. The checks numbered 4,864 buds, 85.5 per
cent, of which set, making a difference of 7.5 per cent.
in favor of the checks. A careful examination of the
tables shows that the gas evidently had no effect upon
any of the varieties except peaches, which were slightly
injured by the 0.30 gramme with an exposure of one-
half hour and one hour. In all cases the growth of the
treated buds was nearly or quite equal to that of the
checks. The conditions of the treated buds were not
quite as favorable, after they had been set into the
nursery trees, as those of the checks. The treated
buds were set a little out of season, somewhat later
than the checks. They were also placed about four
inches above the checks, where they were too high to
be protected by the earth thrown against the trees
during the fall cultivation. They were also placed on
the furrow side of the trees, thus endangering them to
injury during cultivation. These unfavorable con-
ditions were probably, in large part, the cause for the
failure of the treated buds to set equally as well as the
checks."

Sirrine* s folding fumigator. — Another type of
fumigator has been developed and used by Prof. F. A.
Sirrine, of the New York Agricultural Experiment

RECENT WORK WITH HYDROCYANIC ACID GAS 2IJ

Station. This fumigator is about n^ feet high and
S)4 feet in diameter. As shown in Fig. 82, it is six-
sided and is intended to fold up when not in use.

FIG. 8O — THE SIRRINE TYPE OF FOLDING FUMIGATOR

Kach of the six sides is rectangular and rigid. They
are fastened together by hinges. When in use the
whole fumigator is made rigid by a series of cross-
braces. The top is held in place by a series of hooks.

2l8 FUMIGATION METHODS

The front of the fumigator can be opened as a double
door of a width equal to the shortest diameter of the
box. Unbleached sheeting so treated as to be gas-
tight is used as a cover. Careful tests with this fumi-
gator showed that it was practically gas-tight.

Fumigation of orchard trees near Albany. — A series
of tests were made by Dr. E. P. Felt, State Kntomol-
ogist, in the spring of 1900, with hydrocyanic acid gas
for the purpose of ascertaining its efficiency and prac-
ticability in the latitude of Albany, N. Y. A canvas
tent 6x6x8 feet with a fixed pyramidal hood 7 feet
high, as shown in Fig. 81, was constructed of eight-
ounce duck thoroughly oiled with boiled linseed oil.
The rectangular part of the tent was supported on a
light wooden frame, to reduce the variation in cubic
contents as much as practicable. The tent was lifted
with a thirty-foot pole and eight-foot gaff, and thus
dropped over the tree. The hood was kept extended
during the process of fumigation, as shown in the fig-
ure, illustrating also the manner of guying the pole
and tent. The tent and apparatus for handling it cost
about $38, but they could undoubtedly be made for less
when several were needed. A good pole and gaff from
near-by woods could be gotten at little expense. The
bottom of the tent was provided with what Dr. Felt
calls a " sod cloth." It consists of a flap six to eight
inches wide, which was covered with earth to prevent
the escape of the gas. An uncovered space was always
left on the windward side for the insertion of the
chemicals. The trees in these tests were exposed to
the gas for 35 minutes. After fumigation the guy-
lines were released, the sod cloth uncovered, and the

FIG. 8l — FELT TYPE OF CANVAS TENT WITH PYRAMIDAL
HOOD

220 FUMIGATION METHODS

tent quickly raised and dropped over an adjacent tree.
It is quite important to have the pole on the windward
side of the tent.

The trees were fumigated April 19, 20 and 21,
using one ounce of potassium cyanide to 75, 100 and 150
cubic feet of space respectively. The trees fumigated
were peach and pear, several varieties, and the buds
were beginning to swell. The outcome of the tests
showed clearly that the scale was all killed, even on
trees where the gas was used at the rate of one ounce
of cyanide per 150 cubic feet of space enclosed.

A

CHAPTER XX
ECONOMIC VALUE OF FUMIGATION

FTER a most careful consideration of the sub-
ject of fumigation with hydrocyanic acid gas
from every point of view, the writer is of the
opinion that it is indispensable in orchards,
nurseries, greenhouses, mills, elevators, and various
other enclosures where insect pests are to be destroyed.
Nothing is more easily applied, and certainly no other
material has been found so deadly to animal life. Its
cheapness, quick diffusion, and thoroughness make it
a practical remedy for ready use in many ways. In
addition to the many methods cited, it can be used to
good advantage for the destruction of animals, such as
dogs, cats, etc., rounded up and captured in large
cities. Such animals, including old or injured horses
and cattle, could be easily and painlessly put to death
by being enclosed in a room in which this gas could
be generated.

It is not beyond human possibility that it may
supersede the primitive method of hanging and the
more modern idea of electrocuting criminals. Cells or
death chambers could be made in any enclosure in
which hydrocyanic acid gas could be easily generated,
and the occupant painlessly and instantly put to death,
without any of the horrors accompanying the gallows
and electric chair. From the humanitarian point of
view it certainly deserves consideration.

221

222 FUMIGATION METHODS

The following letteis or quotations from scientific
and practical men who have either used hydrocyanic
acid gas or are thoroughly familiar with its properties
and economic values are interesting in this connection.
We have alluded to the early history of the discovery

FIG. 82 — FUMIGATED CITRUS

Orchard of J. W. Henderson, near National City, California, only a
short distance from the Stearns ranch, on which Fig. 83 was
taken. Orchards about the same time. Note the difference.

of the gas as an insecticide in Chapter I. There seems
to be some misunderstanding as to its first application
to nursery stock. In the "Year-Book of the United
States Department of Agriculture for 1899," Dr. L,. O.
Howard, Entomologist, is of the opinion that he first
recommended the use of hydrocyanic acid gas as a dis-

ECONOMIC VALUE OF FUMIGATION

223

infectant for nursery stock. The writer being aware
of the use of this gas in California upon nursery stock
as early as 1890, wrote Alexander Craw, State Ento-
mologist and Quarantine Officer of California, who re-
plies as follows :

First use upon nursery stock. — "Fumigation by

FIG. 83 — SPRAYED ORANGE TREE

Orchard of W. F. Stearns, near National City, California
(Photograph by H. R. Fitch, July 18, 1901)

hydrocyanic acid gas was practiced in Southern
California for the disinfection of nursery stock as
early as 1889-90. Upon page 479 of the ' Report of
the California State Board of Horticulture for 1890'
the following reference to fumigating nursery trees is
made : ' The Commission has used the utmost vigi-

224 FUMIGATION METHODS

lance in causing all Flprida trees to be disinfected by
both dipping and gas treatment. The red scale of
Florida, Aspidiotus ficus, has been introduced on im-
ported trees, but was without doubt eradicated by the
gas treatment that the trees received. ' This is over the
signature of F. Edward Gray, at that time one of the
Horticultural Commissioners of L,os Angeles County,
'California. In June, 1891, a shipment of 325,000
oranges arrived at the Port of San Pedro from Tahiti,
and were fumigated with hydrocyanic acid gas.

' * During the above years the county commissioners
in Southern California demanded certificates that nur-
sery stock had been fumigated or dipped. Dr. L. O.
Ho ward's history of fumigation, as printed in the 'Year-
Book for 1899, United States Department of Agricul-
ture,' is not correct. I notice on page 151 of that re-
port that he considers, in 1894, ne was the first to
recommend fumigation of nursery stock before delivery
to purchasers. I know that previous to 1894, as cited
above, that hundreds of thousands of nursery trees had
been fumigated in California before being delivered
to purchasers. The fact of the matter is the United
States Department of Agriculture had practically noth-
ing to do with the discovery of the gas treatment, as
Mr. Coquillett was not then in the employ of the
Department."

Fumigate greenhouses regularly. — I fumigate my
greenhouses and cold frames about four or five times a
year with it, and have thus been able to keep down all
insect and animal pests except the red spider. How-
ever, about 80 per cent, of the red spiders are killed
by the regular treatment recommended, but to com-

ECONOMIC VALUE OF FUMIGATION 225

pletely control the spider it is necessary to use water
under pressure. — Dr. ALBERT F. WOODS, United
States Department of Agriculture.

Olive trees fumigated. — In more than a score of
instances in Southern California olive trees have been
fumigated with the most satisfactory results. Trees
which had not borne fruit for several years, after an
application of fumigation, bore very heavy crops.
The olive trees had been affected by black scale and
smut which was totally destroyed by the application
of fumigation. Peaches, apricots, plums, apples, and
pears fumigated have brought large crops and superior
fruit, not alone in flavor but also in size. Deciduous
trees must be fumigated while they are dormant before
the fruit buds or leaf buds begin to unfold or after the
ripe fruit has been taken from the trees. This, in
fact, we consider the best time to fumigate. It is a
serious blunder to neglect to avail one's self of the
advantages of fumigation in the belief that it is an
expensive operation. Quite the contrary is the case.
It makes but a small part of the orchardists' expense
while the benefits ramify in every direction. — The
Rural Calif ornian.

Fumigation understood and appreciated. — A fumi-
gated tree conserves its energy and produces clean
fruit, having a brighter color and a better flavor than,
fruit which has gone through the process of washing
and cleansing, and brings from 20 to 25 per cent, more
in price in the market. The washing of oranges and
lemons to remove black, purple, or red scale often
breaks the skin and spoils the appearance and flavor of

226 FUMIGATION METHODS

the fruit. Fruit thafc has required washing is fre-
quently unsalable when clean grown fruit is seen be-
side it. This is a fact well understood and appreciated
in the districts where the application of cyanide gas is
practiced. Any one wishing to convince himself of the
vast superiority of fumigating over the old spraying
methods only needs to visit the orchards of Duarte,
Monrovia, Azusa, Covina, Pomona, and Riverside,
and consult the Horticultural Commissioners. It may
safely be stated that 99 out of every 100 of the Horti-
cultural Commissioners in the country are heartily in
favor of fumigation with hydrocyanic acid gas. — The
Rural Calif ornian.

( ' Does it pay to fzimigate ?" is answered by editor
C. M. Heintz. He says: ' ' This question is asked daily
The Rural Calif ornian, and we wish to state that there
is nothing known at present which will assist the fruit-
growers all over the United States as much to eradicate
scale-insect pest as the process of fumigation. We in
California have tried it for years, have been benefited
by the operation, and permit us to say if it had not
been for the fumigation procedure the citrus fruit in-
dustry of California would have been a lamentable
failure.

' ' The actual and continuous use of hydrocyanic acid
gas has demonstrated beyond the question of a doubt
that by exterminating the scale insect the citrus fruit-
grower has marketed a profitable crop. Districts like
Riverside, Ontario, Pomona, Azusa, Orange, Tustin,
Colegrove, San Dimas, Lamanda Park, and portion of
San Diego County, will each testify to that which we
state, namely ^fumigation pays, and pays three hundred-

ECONOMIC VALUE- OF FUMIGATION 227

fold. The importance of freeing orange and lemon
orchards of the red, purple, and black scale at this
particular season when the insects commence to breed
must be obvious to every grower. It means when the
shipping season opens healthier trees, larger crop, and
gilt-edge fruit, and an increase of receipts.

' ' These are f acts and considerations that no com-
mercial grower can ignore, and are of such vital im-
portance that unless conscientiously practiced the
chances are five to one that failure to realize a profit
from his trees can be traced directly to neglect in this
direction. We also know that the time has come
when every nurseryman in this country will find fumi-
gation a necessity in order to keep clean his nursery
stock, not alone for his own protection, but for his
customers as well."

In a paper read recently by J. W. Jeffrey, Horti-
cultural Commissioner, L,os Angeles County, at the
Fruit Growers' Convention, he said : {< Fumigation was
more universal last fall than at any other time. It has
been reduced to a science, and while the practice is not
always successful, poor work is no longer tolerated
without penalty upon the fumigator. There is little
complaint of impure cyanide, but much of its improper
applications. Daylight applications, or, more prop-
erly, warm weather fumigation, is under ban, but a
few otherwise practical growers have not discovered it.
Two or three of the leading citrus counties do this
work at the treasury's expense, afterward collecting
from the lands treated. Los Angeles still requires the
orchardists to do their own fumigation. No new
scale pests have developed since your last reports were

228 FUMIGATION METHODS

out, nor is there evideftce that parasites have taken the
contract to disinfect the orchards of Southern Cali-
fornia."

The practice among the fruit-growers giving their
fumigation to the lowest bidder is a bad one. The
question should not be how cheap you will do it, but
how good will you do it? And, again, the work
should not be let by the tree, but by the hour. We
do not deem it necessary to dwell upon the efficacy of
fumigation, as we are confident that no one will dis-
agree with us when we say that fumigation has been,
and still is, the salvation of the citrus fruit industry
of Southern California. — W. H. PAYNE, Horticultural
Inspector, California.

Recently The Rural Calif ornian quoted the follow-
ing from Professor Cook : ' ' Fumigation has been so
long and favorably known that we do not need to speak
its praises. * By their fruits ye shall know them. ' The
fruits of fumigation are the thousands of dollars saved
to the citrus growers of Southern California.

' * We must remember that the foliage on orange
trees is very dense, even more so than on the lemon,
and it is not easy to reach every scale insect. Here,
as I have often urged, is the rock on which the spray-
ing process will split if anywhere. It is yet to be
determined whether even in careful hands the spray
can be thorough enough to be effective in the orange
orchard. ' '

The superiority of fumigation with hydrocyanic acid
gas as a remedy for the destruction of red, black, or, in
fact, almost any other variety of scale, is no longer a
question of doubt with people who have tried all

ECONOMIC VAUJE OF FUMIGATION 229

methods for the destruction of scale pests. The in-
creased cost of fumigation over spraying has, however,
induced some orchardists in Southern California to
resort to the cheaper method of spraying. Fumiga-
tion is the only remedy considered at all effective for
the red scale. The amount of cyanide required to
destroy black scale, if done at the proper time, is about
one-half that required for red scale. In addition to
my duties as Horticultural Commissioner, I am also
Superintendent of Fumigation. I have been connected
with the horticultural commission of Riverside County
for the past six and a half years. — R. P. CUNDIFF.

Arizona. — In July, 1900, I employed this treat-
ment for the destruction of the date palm scale, Parla-
toria viflrix, imported with a large consignment of
some four hundred date-palm suckers from Algeria.
We subjected the suckers to fumigations varying from
0.3 to 0.5 per cent. gas. The foliage of the plants,
being of exceptionally hard and impervious nature,
was not injured. — Prof. R. H. FORBES, Director Ari-
zona Experiment Station.

Arkansas. — I am convinced that the treatment
with hydrocyanic acid gas is an excellent method and
destined to become of general service. I have been
recommending it to nurserymen on occasion, though
entirely on the basis of knowledge derived from the
reports of others, such as your own. — Prof. KRNEST
WALKER, Entomologist Arkansas Experiment Station.

Fumigation operations in Canada. — The following
report was furnished the writer by Prof. William
L,ochhead, of the Ontario Agriculture College : In

230 FUMIGATION METHODS

Ontario we are operating under the San Jose Scale
Ammendment Act, passed April i, 1899, Legislature
of Ontario, and the following are the chief clauses or
sections relating directly to the inspection and fumi-
gation of nursery stock:

Portion of the San Jos / Scale Act. — The following
are the sections of the San Jose Scale Act dealing
with the fumigation of nursery stock, 62d Victoria,
Chapter 35:

3. No person shall import or bring, or cause to be imported
or brought, into the Province of Ontario, for any purpose
whatsoever, any plant infested with scale.

4. No person shall keep, or have, or offer for exchange or
sale, any plant infested with scale,,

5. The owner or proprietor of any nursery shall not send
out, or permit any plant to be removed, from his nursery,
without the same first being fumigated by hydrocyanic acid
gas, in accordance with regulations prescribed by order of the
Lieutenant-Governor-in-Council. 62 Vic., Chap. 35.

6. No person shall sell, or dispose of, or offer for sale,
any plant obtained, taken or sent out from a nursery unless
the said plant has previously been fumigated in accordance
with these regulations. 62 Vic., Chap. 35.

7. In case the Inspector finds scale in any nursery and so
reports to the Minister, the Minister may thereupon inform,
by writing, the owner or proprietor or manager of said
nursery of the existence of scale in his nursery, and the
owner or proprietor or manager of said nursery shall not
thereafter permit any plant or plants to be removed from the
said nursery until the Inspector reports to the Minister that
it is safe in the public interest to permit the said nursery
stock to be removed after fumigation. 62 Vic., Chap. 35.

Canadian fumigation regulations. — The following
regulations have been prescribed by order of the

ECONOMIC VALUE OF FUMIGATION 231

Lieutenant- Governor in Council, in accordance with
the provisions of the San Jose Scale Amendment Adi,
passed April i, 1899 :

1. Fumigation must be carried on in a box, room, com-
partment, or house, suitable for the purpose, which must be
air-tight and capable of rapid ventilation. The owner or
proprietor will notify the Minister as soon as preparation for
fumigation is complete. The Minister will thereupon order
an inspection of the fumigation appliances. No fumigation
under the Act is to be carried on until such inspection has been
made and a satisfactory report sent to the Minister.

2. The Inspector, after examining and measuring the box
or house, or other compartment in which fumigation is to be
carried on, will prescribe the amounts of material to be used
for every fumigation, and the instructions as to the same
must be carefully followed out. The Inspector may. if
thought advisable, supply the material for each fumigation in
weighed packages.

3. The fumigation house (which shall include all apparatus
or appliances used in the fumigation, such as generators, etc.)
is to be subject to the orders of the Minister on the recom-
mendation of the Inspector. Subject to the approval of the
Inspector, the fumigation house may be on other lots than
those on which the nursery stock are growing.

*^.' The fumigation is to be by hydrocyanic acid gas, pro-
duced according to the instructions of the Inspector and from
such formulas as he prescribes for the purpose.

5. The fumigation is to be continued for a period of not
less than forty-five minutes. After the expiration of this
time, or longer, and when fumigation is complete, the house
is to be thoroughly ventilated for fifteen minutes at least.

6. No person is to be allowed to enter the fumigating
house until after the ventilation period has expired. Enter-
ing before may prove injurious, if not fatal, as the gas is a
deadly poison.

7. The fumigation of buds and scions may be done in

232 FUMIGATION METHODS

fumigation boxes of not lots than thirty cubic feet capacity,
the same to be subject to inspection and approval.

8. Immediately after inspection of the fumigation house
the Inspector will report to the Minister, and the Minister or
Inspector will thereupon give permission in writing for the
owner or proprietor to begin fumigation.

9. The owner or proprietor of every nursery will attach
to every box and to every package of nursery stock a certificate
as follows, and he will furnish every purchaser who so desires
a copy of the same:

Certificate of fumigation. — This is to certify that this

package of nursery stock, consisting of was

properly fumigated on or about the day of

1901, in accordance with the regulations prescribed by order
of the Lieutenant-Governor-in-Council, in accordance with
62d Victoria, Chapter 35.

Amount of nursery stock fumigated. — We have in
Ontario 117 names on the nursery list, but probably it
would be more nearly correct to say that there are not
more than 100 different nurserymen in Ontario, about
four-fifths of the work being done by five or six of the
largest nurserymen. Three out of every four nursery-
men on the list do nothing more than a local business,
but the four or five large concerns handle an immense
amount of stock. It is somewhat difficult to get informa-
tion from Canadian nurserymen regarding the amount of
stock fumigated. However, one large nurseryman
wrote me as follows : " It is a hard matter to give
any accurate report as to the number of trees put
through our fumigation house in a year, but would
estimate that the trees would be about as follows :
200,000 apples, 25,000 pears, 40,000 plums, 35,000
cherries, 50,000 peaches, 50,000 ornamental trees and
shrubs, 135,000 small fruits — making a total of 535,-

ECONOMIC VALUE OF FUMIGATION 233

ooo." There are four nurserymen doing business
almost as large as the one quoted. On the supposi-
tion that these four nurseries have about the same out-
put and that they do four-fifths of the total business of
the province, the amount of stock sent through Ca-
nadian fumigation houses would be in the neighbor-
hood of two and a half million trees.

Fumigation in Ontario has been limited almost
altogether to nursery stock, and practically nothing
has been done on orchard trees. As far as the
work in the nursery is concerned, I can say candidly
that I am much pleased with the results. No trace
of scale has yet been found on stock which has been
fumigated. It is true that the first year the Act
was in operation houses were built very hurriedly
and frequently in a slipshod manner, and fumiga-
tion was also performed in a half-hearted and be-
grudging manner by the nurserymen, but I have
found no trace of scale on nursery stock sent out that
year. I have made no improvement over the methods
and equipment outlined by yourself. I still follow
your formula as amended and your method of con-
structing fumigation houses. Of course, individual
nurserymen may have special contrivances for fixing
the door and providing ventilation. I find by expe-
rience that the doors and windows are the parts of the
house which are most apt to get out of repair.

Dr. James Fletcher, Dominion Entomologist, who
has had charge of the fumigation houses at the ports
of entry, writes that in the fumigation of the nursery
stock in boxes at the border every bit of packing right
down to the roots is removed, and only the roots are

234 FUMIGATION METHODS

allowed to be covered.. He has found no instance, as
yet, of living scale on any such treated stock.

Orchard fumigation. — One of Canada's fruit grow-
ers writes Professor Lochhead regarding the application
of the tent system of fumigation on small orchard trees
as follows : " We took a common apple barrel, mak-
ing it fit the trees by using a width of ten- cent factory
cotton well soaked in linseed oil, and while wet tacked
it on the barrel. When dry it seemed to adhere to
the barrel, making it practically air-tight. Then I
headed back the three-year-old plum trees, so as to
drop the sacks over them. For large trees we made
tents 6x7x9 feet high, with posts at each end and
sills and plates, these being well braced both horizon-
tally and perpendicularly. Then I made a door,
fastened to one post by three hinges, and shut to next
post by a bolt in center and buttons at the top and
bottom. I measured out factory cotton twenty-six
inches long and sewed three widths together. This
was oiled and tacked on while wet. We put on
top piece first with tacks, then commenced side cover-
ings where the door shuts, and brought it right around
the frame, letting it lap two inches on top and leave a
balance of ten inches to lay on ground, which is cov-
ered with earth. Then a common lath is nailed over
the lap all around the top. When complete cut out
the hole on the side the door hinges on, to allow the
tent to pass over the tree. This will require three
days to dry properly. Trees treated with the last tent
were eight years old and had borne four crops of fruit.
We had to head them back considerably. It takes
three men to handle these large tents, but one man

ECONOMIC VALUE OF FUMIGATION 235

can handle the small ones nicely. In fadl, three men
could manage ten large tents in one hour. From
every appearance now the scale seems to be thoroughly
killed and the trees to be do:ng well."

Certificate of fumigation. — Professor lyochhead says :
' ' In Ontario there is one particular in which we differ
from most of the states to the south of us, and
that is in allowing the proprietor of every nursery
to attach his own certificate of fumigation. Per-
sonally, I think this is neither fair to the nurserymen
nor to the public, but the Department of Agriculture
here in Ontario has never seen fit to appoint official
fumigators to take charge of the fumigation at every
nursery. The department allows the nurseryman to
do his own fumigating and to attach a certificate of
fumigation to every package sent out. The inspector,
of course, and his assistants are moving about during
fumigation time, and the nurseryman does not know
when to expect a visit. Of course, we look after those
nurseryman who live in infested regions. All the
nurseries in the scale-infested regions are examined for
scale, so that there is a double check on all stock sent
out."

Nurserymen willing to fumigate. — "I find that
there is quite a change of opinion regarding the merits
of fumigation within the past year. I can say now,
without hesitation, that nearly every nurseryman is
perfectly willing to fumigate his stock according to
directions, and to do it carefully. He feels that his
reputation and his business are at stake should scale be
found on his stock. We examine every fumigation

236 FUMIGATION METHODS

house twice a year, aud we test it with smoke before
we allow it to be used, in order to show the position of
any possible leakage. For the first two years one or
two nurserymen blamed fumigation for the death of
many of their peach trees, but they have now become
convinced that the damage was done by the very severe
winter of 1898-99."

Connecticut. — I have not used the gas against San
Jose scale, but have examined stock which had been
fumigated and could find no living specimens a year
later. We have used the gas in the tomato forcing
house, using 3 and 2^ ounces of cyanide per 1,000
cubic feet of space to kill white fly, Alerodes vaporarioum
Westwood. The plants were slightly injured at the
top and every insect killed. Have also tried it in a
barn to kill the clover-hay worm, Pyralis co stalls. —
Prof. W. K. BRITTON, State Entomologist, Connecticut.

Florida. — The following timely account of the
work in Florida has been furnished us by Prof. S. A.
Gossard, Entomologist of the Experiment Station:
" We commenced some extensive experimentation in
fumigating orange trees for white fly, Alerodes citri, in
1900. We found that the treatment destroyed the
insects — in fact, practically exterminated them — with
smaller charges than are used by the California people.
Most of our work was done in the daytime, and
while I have not seen the treated trees for several
weeks a report by letter indicates that they are all
right and have a good set of fruit. The trees dropped
from one-fourth to nearly all of their leaves, but put
out again immediately and seem to have a good set of

ECONOMIC VALUE OF FUMIGATION 237

fruit. It would appear, therefore, that dropping the
leaves from the trees is not so apt to work injury to
the orange in Florida as in California. We fumigated
trees of various sizes from mere bushes up to 30
feet in hight and 25 feet in diameter, using various
styles of tents. The hoop tent proved most satis-
factory for trees not over 12 feet in hight and of
equal diameter, but for larger trees we used the bell
tent, handling it by means of a new form of derrick.
We ceased fumigation work when the trees com-
menced to blossom freely, and put the tents away.

" Several hundred trees were fumigated, and four or
five times as many sprayed with resin wash and with
a few other materials for comparison. The gas method
is the more expensive to begin with, but we are inclined
to believe it may be the cheapest in the end. I found
that about seventy -five per cent, of the insects were
killed by a single spraying with resin wash, but in
examining thousands of insects upon many different
trees that were fumigated I was able to find but a
single living representative. I have no doubt that the
practical application of the process to two or three of
our orange-growing counties will mean a net profit of
$250,000 to $500,000 annually inside of three or four
years, if the treatment is generally adopted. We have
not worked with deciduous trees, not because we
believe it impracticable, but for lack of time up to the
present. A number of our nurserymen use the gas in
fumigating their nursery stock, and in a more limited
way plants and shrubs, upon their premises. Nearly
all of our nurserymen doing a large and extensive
business have excellent fumigating appliances.

238 FUMIGATION METHODS

" One form of fumigating box in use by some of
our nurserymen deserves notice. It consits of a
smaller box resting inside of a larger one, about six
inches of space separating the two between the bot-
toms and about the sides, which is filled with loose
sand or clay. The top is either constructed with a
similar space filled in with sand or earth, or may be of
the usual pattern double-boarded with tarred paper
between. This lid has a rim of beveled inch-board six
inches deep, projecting downward and falling into the
sand above mentioned, being brought perfectly into
place by a wooden wedge above. This produces a box
that is absolutely air-tight, and can never have an
unsuspected leak of any kind in it.

" Judging from the evidence in my office, the gas
treatment carefully applied is absolute protection
against San Jose scale and other insect pests upon
nursery stock. I have known instances where much
nursery stock had gone forth infested when fumiga-
tion was either not practiced at all or was carelessly
done, but have failed to learn of a single case of
infested stock going out from the same nurseries after
the stock was carefully treated."

Idaho. — No experimental work with hydrocyanic
gas has been done at this station. The question of
infested nursery stock has not been a pressing one.
In this state I knew of one infested nursery, but it
was abandoned. The owner made some inquiries of
me about the subject of fumigation, and constructed a
fumigating room, which he used for a year or two
with success. As to fumigation of commercial
orchards, there has been none of it here so far

ECONOMIC VALUE OF FUMIGATION 239

as I know. — Prof. J. M. ALDRICH, University of
Idaho.

Louisiana. — We are much interested in the use
of this gas. Some fumigation of orange trees was
made a few years ago, as noted in a special bulletin
from the Louisiana Kxperiment Station entitled, ' ' In-
sects of Orange." We have used hydrocj^anic acid
gas with good results for the cow-pea or bean weevil.
The cow-peas were stored in a closed room and the
amount of cyanide used was according to your own
formula. We have arranged to fumigate plants com-
ing into Louisiana, and it is our intention to use the
gas much more extensively. — Prof. H. A. MORGAN,
Entomologist Louisiana Experiment Station.

Massachusetts. — My candid opinion as to the effi-
ciency of the gas method for the destruction of insects
is that it should be much more widely used, but only
by experienced hands. I believe it to be available for
the fumigation of greenhouses, warehouses, and other
places, but do not believe in its use where carbon bisul-
phide will do the work, considering the latter to be
safer. The Kxperiment Station is strongly in favor of
fumigation, but in the absence of any law on the sub-
ject can only make use of moral suasion. — DR. H. T.
FERNALD, Associate Entomologist, Hatch Experiment
Station, Massachusetts.

In Michigan cheap and reliable. — We now have
excellent spraying laws and others, requiring the
inspection of nurseries and orchards for San Jose scale
and other dangerous insects and diseases, but it has not
been found necessary to require the fumigation of all

240 FUMIGATION METHODS

nursery stock. The San Jose scale has only secured a
foothold in a few localities, and even there has been
confined to comparatively small areas. So far as is
known, there is no San Jose scale within several miles
of any of our nurseries. In one or two instances fumi-
gation has been required where the black peach aphis
has been found in a nursery, and under our present law
it will be possible to compel nurserymen to fumigate
their stock before it is sent out if the scale is found in
a nursery, or in such close proximity that there is a
possibility that the trees may be infested, even though
careful inspection fails to reveal its presence. In case
the scale continues to spread a move will be made to
secure a compulsory fumigating law that will apply to
all nurseries. At the present time it seems the cheapest
and most reliable method of treating nursery stock, as
well as for the destruction of many insects that are found
in buildings. — Prof. L,. R. TAFT, Michigan Agricul-
tural College.

Urges law in Mississippi. — There has never been
anything done with hydrocyanic acid gas in this state.
We have no laws on fumigation of nursery stock, but
I have been urging laws, and think I shall present the
matter to the legislature. — Prof. GLENN W. HERRICK,
Entomologist Mississippi Experiment Station.

Successful mill fumigation in Missouri. — Some nur-
series have erected a fumigating house and have fumi-
gated both the material entering and leaving the
nursery, but no one knows that it ever had the San
Jose scale in any case. Some greenhouses have also
been fumigated, and always with success, but of course

ECONOMIC VALUE OP FUMIGATION 241

this was for the ordinary greenhouse inse<5l pests. I
have never fumigated nursery stock or trees that had
the San Jose scale with hydrocyanic acid gas and then
made careful tests to see if all scales were killed, and
hence I can not speak on that point. Several mills in
this state have been fumigated with this gas, and with
success, but it is difficult to get the mills aired out
properly without danger, unless special arrangements
be made to do this from the outside. This state has
no fumigation laws, and probably will not for some
time. We have only just succeeded in getting a law
passed requiring stock entering the state to bear certi-
ficate of inspection. — Prof. J. M. STEADMAN, Univer-
sity of Missouri.

Nebraska fumigates doubtful stock. — Although we
have done comparatively little in the way of using
hydrocyanic acid gas for the purpose of fumigating
nursery stock, a little has been done in this direction,
chiefly by our nurserymen when they receive stock
from abroad about which they feel a little dubious. —
Prof. LAWRENCE BRUNER, University of Nebraska.

North Carolina. — I think that it is only a question
of a very short time before fumigation will be one of
the regular operations of the nurseryman. Where
there are great interests at stake, I do not think that
laws compelling fumigation are out of place but
rather a necessity. Most people are too much inclined
to look upon fumigation requirements only with
reference to San Jose scale. It seems to me that it is
equally fatal to other insects, and it cannot fail to be
of very great benefit to the fruit grower. The cost of

242 FUMIGATION METHODS

fumigation to the nurseryman, as compared with the
cost to the grower, for spraying, etc., is very small.
Of course a system of fumigation will not do away
with the necessity of spraying in orchards, but it will
greatly decrease the loss that growers now sustain
from the attacks of various insects. — Prof. FRANKLIN
SHERMAN, Jr., State Entomologist, North Carolina.

North Dakota fumigated palms. — Owing to the fact
that the number of fruit trees grown in this state is
very small, and that scale and other insedls have not
yet appeared, its use has not become general. I have
used the gas with very satisfactory results at this sta-
tion to kill the scale on palms. I have known of its
use with equally good results in the destruction of bed-
bugs in houses. — C. B. WA^DRON, North Dakota
Agricultural College.

New Jersey. — Personally I have done so little with
the hydrocyanic acid gas that I do not consider my-
self entitled to any opinion as to its value, i.e., no
opinion formed as the results of original work. The
truth is, I never like to duplicate another man's work,
and as you have been doing the fumigation line most
thoroughly I was willing to accept your results, de-
voting my time to other lines of investigation. — Dr.
JOHN B. SMITH, State Entomologist, New Jersey.

New York. — I have not had much experience in the
use of hydrocyanic acid gas on nursery stock, but from
what I have used and from what I know of it in other
respects, it seems to me to be one of the very best and
perhaps the only satisfactory method of treating young
trees for the purpose of killing insect pests upon them.

ECONOMIC VALUE OF FUMIGATION 243

Were I to buy trees for personal use I should most cer-
tainly insist upon their being fumigated, especially if the
grounds of my neighbor were badly infested with San
Jose scale. I believe fumigation is a good thing aside
from any suspicion of the presence of the San Jose
scale, because it enables a man to start his trees as free
from insect pests as perhaps any process through which
he could put them. — Dr. E. P. FELT, State Entomolo-
gist', New York.

Ohio. — I have not had any reason to change my
former opinion as to its efficiency. Used at the proper
season, I do not know that there is the least danger to
nursery stock, and I do not believe, if properly used,
it is possible for a scale insect to pass through a fumi-
gating house alive. We may say, as among other
things connected with nursery work, and, in fact, every-
thing else, much depends upon whether fumigating is
done properly or improperly. All of the houses that I
have had built have been provided with slat floors and
we have generated the gas underneath. I find this is
much more practical than any other way that I have
tried. Of course for very small nurseries we have
advocated a tight box, but this is only where plants
like raspberries and blackberries are fumigated. — Prof.
F. M. WEBSTER, Entomologist Ohio Experiment
Station.

Pennsylvania. — I have not made a thorough canvass
of our state in regard to the use of hydrocyanic acid
gas, but know that many of our nurseries have con-
structed fumigating houses and are carefully subjecting
infested stock to the gas treatment. This treatment is

244 FUMIGATION METHODS

the most effectual method we have to clean up nursery
stock of its insect pests, and has given great satisfaction
where it has been judiciously handled. There are
cases in which the exposure to the gas was unneces-
sarily long, resulting in marked injury to the trees.
It is useless, of course, to subject trees to the gas which
are free from insects. The gas treatment should find
favor in warehouses, flour-mills, etc., where vermin
are to be destroyed and no life is at stake, but I have
met with no experience in such places. I cannot
recommend it for conservatories or greenhouses where
a mixed lot of plants are grown. In my own experi-
ence I have found many kinds of plants suffer greatly
in an exposure that is too weak and brief to kill all of
the red spiders or mealy bugs. If a single house can
be closed off and the stock is wholly of one kind of
plants, as violets or chrysanthemums or carnations, it
is possible to so adjust the treatment that no injury will
befall the plants and the insects will be destroyed.—
Prof. GEORGE C. BUTZ, Horticulturist Pennsylvania
Agricultural Experiment Station.

Rhode Island. — I believe that the gas treatment for
the destruction of insects upon nursery stock is the
only efficient method for the destruction of certain of
the pests, and personally were I to buy plants for a
large orchard, or for use in the orchards which I
already have planted which are now free from San Jos6
scale, I would most surely buy them from some
nursery which would fumigate trees before shipment.
I believe that as the efficiency of this method of treat-
ment is more fully understood and appreciated by
warehouse and flour-mill owners that this will become

ECONOMIC VALUE OF FUMIGATION 245

the method in vogue for the destruction of insects
which harbor in such buildings. — G. K. ADAMS,
Assistant Horticulturist Rhode Island Experiment Sta-
tion.

Virginia. — In my several bulletins on the San Jose"
scale and reports as state inspector for the same, I
have mentioned more or less frequently the subject of
fumigation. We have never attempted fumigating
orchards or plants of any kind, except nursery stock
in closed houses. Our present formula to each 100
cubic feet of space in room for fumigating nursery
stock is as follows: Fused potassium cyanide, 98 per
cent., i ounce; commercial sulphuric acid, high grade,
i1/;. fluid ounces; water, 3 fluid ounces. This has
proved very satisfactory, and thus far we have no
instance in which it has damaged the stock. I am
happy to say no instance has come to our notice in
which the scale has survived treatment by the above
formula. — Prof. WILLIAM B. ALWOOD, State Ento-
mologist, Virginia.

Sound Advice. — In an address before the New York
Fruit Growers' Association, L,. T. Yeomans, a prom-
inent New York fruit-grower, said: "Our firm has
not planted a tree during the past two years which
has not been fumigated with hydrocyanic acid gas.
We do the work ourselves cheaply, quickly, and with-
out injury to even peach trees, notwithstanding the
assertion of some nurserymen that it is unsafe, ex-
pensive, and dangerous. A nurseryman in western
New York who has fumigated for several years all the
nursery stock he sells, says the expense to him does

246 FUMIGATION METHODS

not exceed 25 cento per 1,000 trees of regular one
dollar size. If all planters would refuse to buy trees
which had not been fumigated, the nurserymen would
see it for their interest to fumigate. I am happy to
say that there are some nurserymen who fumigate all
their stock. No trees can be shipped into Canada
without fumigation, and yet there are some who raise
a cry about the hardships it would be for them if com-
pelled to fumigate stock sold to the grower, yet these
same nurserymen find it to their interests to comply
with the Canadian law rather than abandon their
trade across the border. ' '

Views of a practical fruit grower and nurseryman.
— The following statement was received from C. M.
Hooker, the senior member of the well-known nursery
firm Hooker, Wyman & Co., of Rochester: "I am
strongly in favor of the fumigation of all nursery stock,
when it can be safely done, before dissemination or
planting. This should be done by the nurseryman, but
to be perfectly safe I personally fumigate all stock
planted on our place. I have done so for years, and can-
not afford to take any risk of infestation of San Jose
scale from the carelessness of others. That nursery
stock should be fumigated before planting is evident
from the rapid spread of this pest when it is neglected
and the serious loss of all those who plant infested stock.
All infested nurseries should be compelled to fumigate
their stock if the people are to be safe in buying their
trees.

Answers objeftors. — "The objections which are
made to a law requiring fumigation by some nursery-
men I think are not of great force.

ECONOMIC VALUE OF FUMIGATION 247

"is/. They object to the cost. We reply that it is
proven that it is not over 25 cents per 1,000 trees.

" 2d. Delay of shipment. This cannot be over a
few hours.

"3^. Nobody knows that the process is effectual.
Many tests prove that it is the best known and never
fails if properly done.

"4^. Dangerous to employees. No one was ever
seriously injured by the gas, and with a little care it is
perfectly safe.

"5^. Inspection is sufficient. This has been proven
a failure in many cases. Of course, inspection is
necessary and good so far as it goes, especially in
locating the pest in nurseries and orchards.

" 6th, Dangerous to nursery stock. This does not
prove to be the case when properly conducted. One
nursery firm in Geneva has fumigated over one million
trees without damage to one.

' ' 7/A. Wait for a federal law. Of course this is only
an excuse for delay. We shall never get a federal
law, and in any event should take care of our own scale.

" 8M. Not constitutional. Give us the law, and
we will risk that.

" gth. Other states will retaliate by passing similar
laws. Well, we are not certain what other states may
do, but we should do what is right to protect our
state from the San Jose scale and let other states do
what they think best for their interests. There are
other and more important interests than the nursery
interests, yet it certainly is for the interests of the
nurserymen to keep New York State as free as possi-
ble from the scale.

248 FUMIGATION METHODS

" loth. It is an injury to the nursery business to
agitate the subject. This has been proven false by a
large concern in Geneva, who advertise that they
fumigate all their stock, and paste large cards on their
boxes, stating ' This stock has been fumigated,'' and
have very largely increased their business since they
adopted this process.

' ' The San Jose scale is doubtless with us to stay,
but it is our duty to do all that we possibly can to
keep it under control, and in my opinion we cannot be
too careful about it for the interests of the fruit grow-
ers and every one else in the state. The serious dam-
age to orcharding from this pest may be judged from a
letter I have received from a prominent fruit-grower in
western New York informing me that he expected to
destroy about fifteen acres of valuable bearing trees
this season because they were ruined by San Jose
scale."

Common- sense view. — The following letter from
Isaac C. Rogers, of the Rogers Nurseries, is a plain,
straightforward statement of f acts : ' ' Our f umigato-
rium is a room inside the packing-shed. The great
bulk we usually fumigate in a frost-proof and air-tight
room after we are ready for billing out in the spring;
then the small lots dug from time to time are run into
the smaller room, with an opening at the top for the
escape of the gas through the roof after done. The
expense of fumigating is a small matter. The bother
is a small matter compared with the feeling of security
and the fact that after the trees have been through
that deadly stuff they go out through the country
carrying no mischief and trouble making insects. The

ECONOMIC VALUE OF FUMIGATION 249

extra expense of handling is really a small item. The
only way it bothers us is sometimes in loading a car
there will be a shipment to get off that has to have a
few trees fumigated, and then with thirty minutes out
of an hour taken up with the fumigating one has to
jump around pretty lively to make connections. But
the rush and jump are only parts of the nursery busi-
ness and all in the same line, so we do not mind it.
On an average it costs us 25 to 30 cents per thousand
for the actual fumigation, including the extra hand-
ling.

1 ' We have been fumigating now for three or four
years and have had no trouble from loss of trees as yet,
although we were assured by the antifumigators that
we would have our trees to replace. We are careful to
fumigate the trees when dry, and for that reason like
the fumigating room as a part of the packing-shed
much better than to have it as a separate building. If
the trees come in during a wet day they can be allowed
to dry before being put in the fumigator, and it is far
more convenient to be able to step into the room from
the packing-shed during any kind of weather.

" The objection generally made by nurserymen is
from the fact that a very large part of the nursery stock
grown in western New York does not go direct to
planters, but is shipped here and there to dealers and
nurserymen all over the United States. Nurserymen
in other sections must have their stock shipped early so
they can reship to their customers, probably back in
New York. In order to get this done and the trees
planted before it freezes up, they have to be dug before
they are fully matured. Some nurserymen fear that

250 FUMIGATION METHODS

fumigation will injure them in this condition. There
will be kicks along the line, for frequently trees are
shipped and reshipped, sold and resold, several times
before they are eventually planted, and no doubt fre-
quently set a few miles from where they were grown.
At the other end of the season there are always lots of
people who forget all about ordering until the trees
begin to grow or come into bloom, and then it is too
late to fumigate safely at the usual strength. These
two extremes seem to block the way and prejudice
many nurserymen against fumigation.

* ' We do not have to depend upon the notions of
other nurserymen hundreds of miles away. We can
dig, fumigate, and pack our trees when the right time
comes. This accounts, in part, for our not being * in
the ring,' as it were, fighting our own interests, as some
nurserymen have been doing. In some cases with a
large majority of tree growers in New York there is
really no connection or kindred interest between them
and the fruit grower. Their product is frequently sold
before digging-time, to go in car-load lots to other
nurseries hundreds of miles out of New York, and little
or nothing do they care what becomes of the trees after-
ward or whether they are planted in New York or in
South Africa."

Protects customers. — We are thoroughly convinced
that fumigation is most necessary in order that the
grower of nursery stock may supply his customers
with trees and vines absolutely free from all insect life.
While most nursery stock grown in this section is not
infested with San Jose scale, yet all is more or less
infested with aphis and other troublesome forms of

ECONOMIC VALUE OF FUMIGATION 251

insect life, that can but be deleterious to the tree if
allowed to remain thereon in an active condition. For
the past two years we have fumigated everything that
we have sent out except evergeens, and so far have
never detected any injurious effects. — THE R. G.
CHASE COMPANY, Nurseries, New York.

Utah. — We believe this is the most efficient treat-
ment that nursery stock can be given. If the build-
ing is air-tight and the chemicals are mixed in the
proper proportion, it is undoubtedly destructive to all
kinds of insects and no harm results to the stock.
After putting gas into the building we leave our stock
stand from one-half to three-fourths of an hour, then
throw the double doors wide open, and allow the
building to ventilate from fifteen to twenty-five min-
utes before attempting to remove the stock. We
believe it pays us to run all nursery stock through our
cyanide house. We have treated from two to three
hundred thousand trees annually for the past three
years. In 1901 we expect to treat half a million. If
one had more stock than this it would be advisable to
build a larger house. We think it quite necessary to
have the roots of the trees comparatively clean. If
they are covered with dirt, especially clay soil, the gas
may not penetrate to the insects, especially woolly
aphis. Do not think our building cost to exceed $50.
—VAN METER, HARNESS & Co., Proprietors Davis
County Nurseries, Utah.

Utah. — I have followed your directions for fumi-
gating, which have proven very satisfactory. I have
had no opportunity for experimenting with scale, but

252 FUMIGATION METHODS

find the gas a sure remedy for woolly aphis and other
insects. — D. M. MOORE, Moore's Nurseries, Utah.

Opinions of orchardists on fumigation in New South
Wales. — Bevan Brothers, of Galston, write W. J.
Allen, the government expert, as follows: " We have
fumigated some 1,500 trees since this time (July) last
year, and the results have been very satisfactory.
Without doubt nearly every scale has been killed, the
trees are healthy, and the fruit clean. We formerly
sprayed from three to four times a year, tried several
preparations, and never got thorough satisfaction out
of any. Occasionally patches of live scale do remain
on trees that have been fumigated, but, as far as we
can judge, this has only happened where fruit with
scale on it has pressed against the side of the tent, or
where the dose of acid has not been quite sufficient to
poison the scale on the lower limbs.

1 ' Several of our neighbors having seen the results
on our trees have had tents made, and set to work
cyaniding. This is surely the best proof of its value.
You are aware that we use a cheap tent made of calico,
costing wholesale about is. $d. per yard, double width.
So far this has answered admirably. Tents 10 feet in
diameter by 12 high cost from 305. to 355. This re-
duction in the cost of the tent really made fumigation
possible to us. We have had to thank your depart-
ment for many things, but for none are our thanks
more deserved than for teaching us cyaniding. ' '

R. If. Sheppard, Wesbank, Emu Plains, says in
same report : "I was prompted to enter upon what
seemed at first rather an arduous undertaking, viz.,
the fumigation of my citrus trees for the destruction of

ECONOMIC VAIJJK OF FUMIGATION 253

scale, by a practical demonstration given by W. J.
Allen, government fruit expert, who at the same time
placed at my disposal a large amount of useful infor-
mation for my guidance at the start. The first diffi-
culty which presented itself was that of procuring
tents — how many to get, what sizes, and where to get
them at a reasonable cost. Firms in Sydney asked a
price that was practically prohibitory. In my diffi-
culty I applied to Mr. Walter Bevan, of Galston, who
at this time was having his trees treated by this pro-
cess, and he it was who put me in the way of getting
them at a moderate figure. The least expensive
method is to buy the material at some wholesale house
and have it made up at home. For the purpose noth-
ing could be better than ' circus- tent calico, ' both for
lightness and durability. At present the wholesale
price is is. $/4d. per yard of 6 feet wide.

' ' In my opinion no grower should bother with
tents, but have the material made into square sheets
the sizes he requires. They are easier to make than
tents, answer the same purpose exactly, and are much
more readily placed over the trees. The number to
get and the sizes will naturally depend on the trees
the grower has. I got four tents and two sheets, each
sheet being 40 x 40 feet, and with this number two
men can do from 30 to 50 trees each day. I began
fumigating about the end of January last, and instead
of doing the work at night, which is generally accepted
as the proper time, I did all mine by daylight. Orange
trees badly infested with scale, I found, lost a large
portion of their leaves, those with less scale a much
smaller quantity. Having the cyanide broken up too

254 FUMIGATION METHODS

finely, and thus causing the gas to generate very quickly,
seemed to tend to defoliation as much as anything.
However, a very strong, new growth started, and the
trees soon assumed a splendid appearance. Curiously
enough, lemon and mandarin trees, though treated in
the very hottest days, lost no leaves at all. Fumiga-
tion, no doubt, is the only royal road to clean trees —
it absolutely blots the red scale out, and if done before
the fruit is too large, a clean crop is assured, as the
expansion of the fruit causes the scale to drop off.
Brown olive scale is decimated, but not always alto-
gether destroyed, though it looks as if, of the two, it
would be easier to kill. So far I have treated 1,800
trees of various sizes, and I am sure growers will be
pleased to know that the average cost per tree, includ-
ing labor, price of tents, chemicals, etc., only amounts
to T%d. Thus for *]d you get a healthy tree and clean
fruit. How much more is this worth than a sickly
tree and unmarketable fruit? To show how fumiga-
tion is regarded on Emu Plains, I can inform those who
are in doubt that since my neighbor growers witnessed
the effect of the treatment here some have already com-
menced, and others contemplate doing so."

M. Brown, of Messrs. Rodgers & Co., Galston,
writes Mr. Allen as follows: "We have fumigated
this year some i , 800 trees, and are entirely satisfied
with the result. We started fumigating the first week
in May, and a live scale cannot be found on any of the
trees done. Fully 50 per cent, of the scale have been
cleaned off the trees, and I hope to see the greater part
of the remainder cleared off before the bulk of the
fruit is marketed. Of course, you will understand

ECONOMIC VALUE OF FUMIGATION 255

that May is too late to commence fumigating to obtain
the best result, but we could not start earlier, and
next year I intend to start early in February, so that
the oranges, while still growing, will throw off the
dead scale. My reason for starting in February is that
I have done some experimenting, and have closely
watched the result, and feel sure that citrus trees done
in that month will be almost absolutely clean by May.
I did some twelve or fourteen of the worst trees I
could find in the orchard fourteen months ago with the
government tents which you lent me, and at the pres-
ent time they are almost perfectly clean ; what little
scale there is on them has only come in the last two
months.

' ' As you know, I have had some experience with
spraying, and have tried practically every known
spray, and also had Mr. Chomley up here experiment-
ing with different sprays, and I have no hesitation in
saying that spraying is a thing of the past, and quite
out of date compared with fumigation, as the fumiga-
tion gives a ten times better result, and is not nearly
so costly, once you buy the tents, and these are not
very expensive. I bought strong unbleached calico,
double width, wholesale, at is. 2d. per yard, and find
this will hold the fumes as well as canvas, if it is not
blowing a strong wind. I got 200 yards, which made
nine tents of various sizes (but all of them are a good
size), and cut the stuff out myself in the following
manner : Cut out a circle 6 feet in diameter, then one
length of calico 30 feet long, and sew round the circle ;
then cut out another length 30 feet long, and join on
the other piece and sew up the seam ; this will give

256 FUMIGATION METHODS

you a tent which will cover a well-grown ten-year-old
orange tree, provided the tree is not more than 13 feet
high.

( ' What I should like to see the government do is
to get together a large plant (say, twenty-five tents)
and employ four men to manage it, and go round to
various orchards in each district and fumigate them,
charging the owner the cost of cyanide, etc., labor,
and enough to allow for wear and tear in tents, and
interest on their outlay for same, as I feel sure many
orchard owners would be only too glad to have their
orchards done, but they have not the capital to spare
to get the necessary plant, as one wants a fair num-
ber of tents to do the work quickly. I find myself
and one man can manage fourteen tents comfortably.
Your formula of one cyanide, one acid, and three water
is not sufficient to work off the cyanide in forty-five
minutes, so I use one, one-and-a-half of acid, and
three. You are welcome to publish all of this if you
think it of any use, and to say that I strongly urge
growers to go in for fumigating, as there is nothing else
to compare with it in efficiency and cheapness. ' '

CHAPTER XXI
FUMIGATION WITH CARBON BISULPHID

T"!HE fact that carbon bisulphid volatilizes readily,
has fumes heavier than air, creates an atmos-
phere in -which no animal life can exist, and
can be used without injury to edible materials,
all combine to make it one of the very best substances
for the destruction of certain subterranean insects and
other undesirable animals. For killing insect pests in
stored grains and other materials in bulk it has no
superior. Its vapor will penetrate to the lowermost
cracks and crevices in a granery, carrying the death-
dealing atmosphere with it. It can be used economic-
ally where hydrocyanic acid gas cannot be employed
on account of its heavy vapor.

First use of carbon bisulphid to destroy inseEls. —
During 1856 and 1857 M. Doyere used carbon bisul-
phid as an insecticide. He demonstrated that it could
be used to destroy weevils and other pests in corn and
barley without injuring the grain either for planting
or edible purposes. Since that time it has been used
for combatting various insect pests. At first the cost
of carbon bisulphid precluded its general use as an
insecticide on a very extensive scale. Largely through
the efforts and inventive genius of Kdward R. Taylor,
a manufacturing chemist, a grade known as " Fuma
carbon bisulphid ' ' was placed upon the market a few
years ago. It is now the standard for insecticide pur-

257

258 FUMIGATION METHODS

poses and is sold at a $>rice within reach of those who
desire to use if for economic purposes.

Chemical properties. — Carbon bisulphid is a color-
less liquid resembling water. It is formed by the
union of two elementary particles of sulphur with one
of carbon (charcoal) ; thus the chemical symbol CS2.
It is made on a large scale by a new electric process
invented and patented by Edward R. Taylor. The
fumes of burning sulphur are passed over red-hot
charcoal and the resulting vapors are condensed to a
liquid by cooling. Mr. Taylor's new plant at Pen Yan,
New York, has a daily capacity of 20,000 pounds at
present. The liquid is one-fourth heavier than water.
Its specific gravity is 1.29 at the freezing temperature
of water. It is very refractive, reflecting light much
more readily than water when its surface is disturbed.
It is extremely volatile and evaporation is rapid when
the surface is exposed to the air. The temperature of
the liquid and the air, as well as the evaporating sur-
face, determines the rapidity of evaporation. By cov-
ering the surface of carbon bisulphid with water,
which is lighter, evaporation can be prevented.

Carbon bisulphid is not necessarily dangerous to
the skin, but when the fingers or hands are frequently
moistened with it the skin becomes rather dry and
harsh and liable to crack or chafe. On account of its
volatility it absorbs considerable heat. Perfectly pure
carbon bisulphid has an acrid taste and a rather
sweetish, not disagreeable, etherial odor, similar indeed
to that of ether or chloroform. Pure carbon bisulphid
will not injure or stain the finest garments or fabrics.
It can be poured directly upon food stuffs without im-

FUMIGATION WITH CARBON BISULPHID 259

pairing their edibility. All trace of the odor dis-
appears quickly when such produces are exposed to
the air. The ordinary commercial article has a slightly
yellowish tinge due to its impurities, which also give
it a rank fetid odor that is extremely obnoxious.
When an impure article is used, a slight residue may
be left after the evaporation of the liquid. Such a
grade will stain fabrics, and it should be poured upon
food stuffs with care, though its vapor will do no harm.
Liquid carbon bisulphid is not explosive, and there
need be no fear of handling it, provided the vessels are
perfectly tight. It should be kept where there is no
fire in a dry place, so the cans will not rust. Carbon
bisulphid boils at 115° F. One volume of the liquid
is said to give 375 volumes of vapor upon evaporation.

Properties of vapor. — Owing to its heavy properties
the vapor of carbon bisulphid can be poured from one
vessel to another, like water. It is 2.63 times heavier
than air. It diffuses quite readily through the air, as
can be perceived by its odor. It has a tendency to
seek lower levels, and consequently will be more dense
as it works downward. This fact should be borne in
mind, as it has an important bearing upon the applica-
tion of this material. It is the opposite of hydrocyanic
acid gas, which is lighter than air. Carbon bisulphid
in both liquid and vapor form is an efficient disinfectant.
Meats have been kept in its atmosphere for many weeks.
The disinfectant is the same gas as is formed by burn-
ing sulphur or brimstone.

Inhaling the gas. — The extreme effects of the vapor
of carbon bisulphid if inhaled are giddiness, vomiting,
congestion, coma, and death. The material can be

260 FUMIGATION METHODS

used in mills, warehouses, and other enclosures with
perfect safety. A reasonable amount of the vapor can
be inhaled, while the liquid is being distributed in a
building without injury to the operator. From per-
sonal experience in making many practical applications
of carbon bisulphid in buildings, the writer has never
experienced any ill feeling or bad after-effects from
the gas. The sense of smell is the first affected. If
one is confined in a room where the gas is being gen-
erated, for a short time the olfactory organs are
benumbed or deadened. As the oxygen in the lungs
becomes exhausted, the heart-throbs become more
rapid. The mind becomes sluggish, while hearing and
sight are weakened. This is usually followed by dizzi-
ness. The sensation is not disagreeable, and a person
has no immediate desire to get out of the gas. A
person in this condition should leave the building being
fumigated at once and freely inhale fresh air.

Mr. W. E. Hinds, who has had some experience
with the practical application of this gas, in a recent
Farmers' Bulletin (No. 145) by the United States De-
partment of Agriculture, says : ' l Owing to the effect
of the gas upon the heart action, it may be well to
caution persons having any trouble or weakness about
the heart against taking any extended part in the
application of the bisulphid. It should be clearly
understood by those who use it that the action of the
gas is somewhat poisoning as well as suffocating.
Should the operator persist in remaining in the room
after the dizziness comes on, he will be in danger of
falling, and, if not discovered, he will soon suffocate.
Even if he should get out safely, the ill effects will be

FUMIGATION WITH CARBON BISULPHID 26 1

more marked and a severe headache, at least, might
ensue. If upon the approach of dizziness, the operator
goes at once to a window, or better still out of doors,
an abundance of fresh air will in a few minutes remove
all ill effects, and no injury will result from the experi-
ence. The inhalation of the fumes can be somewhat
retarded by tying a wet handkerchief tightly over the
face. This, however, merely diminishes the amount of
air taken into the lungs without affecting the propor-
tion of vapor contained therein. ' '

When obliged to enter a room in which the air is
charged with any considerable amount of vapor, Mr.
Hinds makes use of the following simple device, which
is perfectly effectual : A large paper bag holding 20
quarts or more is tied tightly around a short piece of
tubing of glass, rubber, or metal. When inflated,
the bag contains sufficient air to enable one to respire
into it for several minutes without discomfort. Being
very light, it can be carried by the tube in the mouth,
thus leaving the hands free for any work desired.
Carbon bisulphid can be handled with much greater
safety and far less fear than is possible where the user
knows there is danger but does not know just what the
danger is. The danger from its use is practically of
the same kind as that from gasoline, which is in com-
mon daily use. The danger is very much less, how-
ever, since every precaution is taken to keep carbon
bisulphid from the proximity of fire, while gasoline is
used principally in connection with it.

Commercial uses. — Although the insecticide proper-
ties of carbon bisulphid were discovered by Doyere in
1856, and tested three years later by Baron Paul The-

262 FUMIGATION METHODS

nard, it remained for M. Cornu and M. Mouillefert, two
French investigators, to determine its real value in
this connection nearly twenty years later. They ex-
perimented upon many species of insects representing
various groups, paying particular attention to the
grape phylloxera, the most serious pest to the vine-
yards of France. They found that an atmosphere
containing one part of carbon bisulphid and nine parts
of air killed insects within a few seconds when con-
fined in the vapor ; and that one part in 254 parts of
air was also fatal in about one and one-quarter hours.

The application of carbon bisulphid for the de-
struction of insects in mills, elevators, and other places
where large quantities of grain is stored is of recent
origin. Its extensive use to kill gophers, ground
squirrels, and other noxious subterranean and undesir-
able rodents is a comparatively new method.

In the arts it is employed as a solvent of sulphur,
phosphorous, oils, resins, caoutchouc, gutta-percha,
etc. It is indispensable in the manufacture of rubber
and waterproof goods. In the manufacture of woolen
goods it is used to abstract oils and fats from the wool.
It is not considered an extra hazardous material,
otherwise it wrould not be so extensively used.

Work in France against Phylloxera. — The treatment
of vines in France with carbon bisulphid for the
destruction of phylloxera is very extensive. Some
years more than a quarter of a million acres receive
treatment. Upon being introduced into the soil at some
depth below the surface the liquid evaporates as it
does in the open air, but much more slowly. The
vapor diffuses through the air spaces of the soil. It

FUMIGATION WITH CARBON BISULPHID 263

produces an atmosphere fatal to all insects within its
reach. The rapidity of evaporation, extent of dif-
fusion, and persistence of the vapor in the soil vary
widely in different soils. It evaporates most rapidly
in a warm, dry, sandy soil. The persistence of the
vapor is also shortest in such a soil, and it diffuses so
rapidly most insects will survive an ordinary dose.
The treatment cannot be successfully applied on such
a soil in its dry condition. On the other hand, diffu-
sion is slowest in heavy, wet, clay soil; and when such
soil is saturated with water it is almost entirely pre-
vented. Moisture lowers the temperature and de-
creases the permeability of the soil ; it also prevents
the evaporation of the liquid, and thus retards diffu-
sion. Between these two extremes there is a medium
condition of moisture which is most favorable for treat-
ment.

Action in different soils . — Sandy soils permit an even
but too rapid diffusion of the vapor. Rocky soils are
not of even texture, and naturally the vapors follow
the lines of least resistance. Heavy clay soils, when
very dry, are usually much broken by cracks and
fissures, which may run from the surface to a consider-
able depth. Through such fissures the vapor escapes
rapidly without permeating the soil to any extent, and
its insecticidal value is therefore slight. But when
such a soil is well moistened it is even in texture and
very favorable to treatment. The depth of the soil is
an important factor in determining how much carbon
bisulphid must be used for a given area. If the soil is
shallow and the subsoil very dense and impervious, it
is evident that much less liquid will be required to

264 FUMIGATION METHODS

produce a death atmosphere than will be needed in a
soil of much greater depth. In soils of the same
character and condition the amount needed will be
proportional to the permeable depth of the soil. In
heavy, compact soils increase the number of injections
and diminish the dose; in light, deep, permeable soils
decrease the number of holes and increase the dose.

In field experiments with the grape, using plain
carbon bisulphid in quite fresh soil, vines withstood
105 c. c. of carbon bisulphid, nearly 4.4 ounces,
divided equally among three holes placed about 16
inches from the base of the vine and at a depth of about
20 inches; but 180 c. c. , 7^ ounces, proved fatal to
the vines. In warmer, drier, more shallow soil a dose
of 90 c. c. per vine, similarly placed, proved fatal.
After considerable rain, when the ground was quite
wet, a vine withstood 260 c. c. of carbon bisulphid,
and some vines are said to have withstood 400 c. c.
The treatment should never be applied for some time
after plowing or cultivating, as a firm, compact, moist
surface is much more favorable to the retention of the
vapor. For the same reason about fifteen days should
be allowed after treatment before cultivation is re-
sumed. If the soil is either very wet or dry, treatment
should be withheld. To be in the most favorable con-
dition for treatment, the soil should be quite moist and
moderately permeable, with a firm, even surface, well
compacted by rain and having a depth of at least eight
inches.

The extent of diffusion of the vapor determines the
distance apart at which the injections must be made to
reach all parts of 'the soil evenly and effectively. This

FUMIGATION WITH CARBON BISULPHID 265

varies considerably with the amount of the dose, the
temperature and humidity of the soil, and other con-
ditions. It has been found more satisfactory to employ
smaller and more frequent doses rather than a few
large ones. A dose of 5 or 6 grammes, */6 to '/4 ounce,
is believed to be thoroughly effective through a radius
of from 1 2 to 20 inches, though it may penetrate much
farther than that. The general rule is to make three
injections per square meter, nearly i'/6 square yards,
in light soils, and four injections in heavy soil. The
holes should be at regular intervals, so as to cover the
ground evenly, and never nearer than one foot to the
base of the vine. To be effective all the ground must
be treated.

On account of the liability of injuring the vines it
has been found best to make the treatment in two small
applications, separated by an interval of from six to ten
days. This decreases the density of the vapor, but
continues its action for a much longer time. It
removes the danger of injuring the vines, and gives
even better results upon the insects than would be
obtained by one large dose. The total amount of car-
bon bisulphid to be used should be divided into as
many equal parts as there are injections to be made.
The holes for the second treatment should be inter-
mediate between those for the first. The depth of the
holes will depend somewhat upon the depth and per-
meability of the soil. The average depth is about one
foot. Holes 1 6 inches deep are desirable on very
permeable soil.

Treatment may be applied at any season of the year;
but, as it is followed by a slight check in growth, it

266 FUMIGATION METHODS

should not be applied either at the flowering or fruit-
ing season, as the check would injure the crop most at
those seasons. The injury to the vines results' from
the killing of the tender, fibrous, feeding roots. It
would therefore be better to apply the treatment before
these roots have started in early spring, or after they
have become hardened in the fall. The condition of
the soil usually favors the spring treatment, and the
condition of the insect is said to make it more suscep-
tible at that time.

Amount to use per acre. — To secure extinction it is
usual to apply about 300 grammes, nearly 10 ounces,
per vine, using 150 grammes in each of two applica-
tions ten or twelve days apart. This will kill ninety-
nine out of every hundred vines. In cultural treat-
ment the amount of the liquid to be used varies from
140 to 265 pounds per acre.

Instruments for application. — One of the principal
difficulties in the first use of carbon bisulphid was to
force the vapors to the desired depth. When first
used below the surface it was poured into holes formed
by driving an iron bar with a maul. The demand for
a more convenient, accurate, and rapid working in-
strument was soon met by the invention of the pal-
injector by M. Gastine. This instrument was later
improved by M. Vermorel. The carbon bisulphid is
placed in a large chamber, from which an outlet leads
down through a series of valves, so adjusted that the
amount of each discharge can be exactly regulated as
desired, and opens near the tip of the pointed bar.
The instrument is forced into the ground by the
handle and the pressure of the foot upon the spur to a

FUMIGATION WITH CARBON BISULPHID 267

depth of about one foot ; the central plunger is then
pressed down and the desired amount of the liquid is
discharged ; the instrument is withdrawn, and the hole
closed with the foot, or, as is usual in extensive work,
another workman follows with a rammer, with which
the holes are closed, and the soil at the same time is
firmly compacted. It is said that two men working
together in this way can make between 2,000 and 3,000
injections per day. One acre will require on the aver-
age from 10,000 to 12,000 holes. Plows have also
been devised for injecting carbon bisulphid into the
the soil, but they are not altogether satisfactory. The
same methods can be applied to other subterranean
insects and underground creatures.

Root-maggots and root-worms. — Both the larvae and
pupae of the cabbage root-maggot are destroyed with
carbon bisulphid. Prof. M. V. Slingerland, of Cor-
nell University, has determined these points with
accuracy, giving the details of his experiments in bul-
letin form. (Bulletin No. 78, Cornell University Ex-
periment Station. ) Where used for the root-maggot
the hole should start 3 or 4 inches from the stem of
the plant and run down obliquely a little below the
roots, where the liquid is deposited. The dose re-
quired varies from a teaspoonful for each small plant
to a tablespoonful for large plants, an equivalent of
about one-quarter of an ounce in the former case and
one ounce in the latter. One injection will be sufficient
if made in time. The conditions of the soil noted
under phylloxera treatment will have practically the
same influence in this case.

A similar method of treatment will be equally

268 FUMIGATION METHODS

effective against the -grape root- worm, Fidia vitidda.
To facilitate the application of -carbon bisulphid the
McGowen injector was invented. It is a very con-
venient instrument, and can be adapted to nearly all
uses of carbon bisulphid for underground insects.

Destroying ants in lawns and other places. — Usually
by careful observation the common ants, excepting,
perhaps, the little red ants frequenting houses, can be
traced to their outside homes. The treatment consists
in making one or more holes in the nest with a stick
or iron bar, one to two feet deep, and pouring into each
hole a couple of ounces of carbon bisulphid. The hole
should be closed immediately. The vapor may be
exploded at the mouth of the hole with a match, in
order to drive the fumes deeper into the chambers. If
the latter method is adopted, the hole should be
covered with fresh earth immediately after the explo-
sion, so as to put out the fire and retain the fumes.
Otherwise a large portion of the gas will be burned
and the efficiency of the treatment considerably
lessened. After the explosion the vapor burns with a
colorless, invisible flame. Carefully observe this point
before an attempt to recharge a nest is made. Other-
wise an explosion might follow, with serious results to
the operator. If a large area is infested the holes
should be about one and one-half feet apart each way.
After the carbon bisulphid has been applied the ground
should be thoroughly watered to prevent too rapid
diffusion of the fumes.

White grubs and mole crickets, sometimes found in
lawns and gardens, can be treated in the manner de-

FUMIGATION WITH CARBON BISULPHID 269

scribed for ants. One ounce per square yard divided
between three or four injections will be satisfactory.
The most favorable time for treating the grubs is after
they descend in the ground in the fall and before they
come up again in the spring. In midsummer many of
the small insects near the surface will escape injury
from treatment. Carbon bisulphid may also prove
useful for the destructive nematode worms.

For borers in trunks of trees clean out the mouth of
the burrow and insert a small quantity of carbon bisul-
phid and close the hole with thick clay or other
material. The borers are easily killed without injury
to the tree. The saving of time fully pays for the
small amount of carbon bisulphid required. A spring-
bottom oil-can may be used for applying the liquid.

Melon plant-lice can be treated successfully with
carbon bisulphid. The method consists in covering
the young vines with tight boxes, 12 to 18 inches in
diameter, made of wood or paper, and introducing
under each box a saucer containing one or two tea-
spoonfuls of carbon bisulphid. The vines of older
plants may be gathered about the hill and folded under
large boxes or tubs. In such cases a greater but pro-
portional amount of material must be used. The
covering is usually left over the plants from three-
quarters to an hour. With 50 to 100 boxes a field
may be treated quite rapidly. This method of intro-
ducing the bisulphid can be improved by boring a hole
about one inch in diameter in the middle of the top of
each box, and fastening a small bunch of cotton- waste,
rags, or any absorbent material. By fitting a stopper

270 FUMIGATION METHODS

in the hole the box Js ready for use. In placing it
over a plant, be careful that the edges set firmly into
the dirt. Remove the stopper, add the desired amount
of liquid, and close it quickly.

Fumigation of mills and other buildings. — Carbon
bisulphid can be thrown directly upon grain without
injuring its edible qualities, and will not effect its vital-
ity in the least. In mills it can be used about the
machinery, spouts and elevators with perfect assurance
that the manufactured products will not be damaged.
I know of no instance where the slightest deleterious
effect has been realized by persons applying it in mills,
although they unavoidably inhale some of the fumes.

The amount of liquid to be used depends ( i ) on the
size of the building, (2) on its tightness, and (3) on
the magnitude of the attack. Where the building is
reasonably tight and but slightly infested, one pound
of carbon bisulphid is sufficient for every thousand
cubic feet of air-space enclosed. If it is somewhat open
or badly infested the amount should be doubled. When
applied to bins containing stored grain, one pound of
liquid to every hundred bushels of grain is commonly
used ; but if the insects are very abundant, twice this
amount should be used.

Methods of application. — A number of ways for using
carbon bisulphid have been suggested and tested. The
most effective manner of applying it in mills consists in
simply pouring the liquid into shallow dishes, such as
soup-plates, pans, or wooden vessels, and distributing
them about the building. Bits of cotton-waste satu-
rated with the liquid should also be thrust into spouts,

FUMIGATION WITH CARBON BISUIyPHID 271

elevator legs, machines, and other places where the
pests usually congregate in great numbers. Spraying
or throwing the liquid broadcast into badly infested
corners, on machines, and other pieces of apparatus
where the pests are particularly abundant, has been
attended with very good results.

Time to do the work, — Saturday afternoon is the best
time for fumigating a mill or large building. After
sweeping from top to bottom, all fires about the premises
should be extinguished and the building closed as
tightly as possible. The vessels and cotton-waste
should be previously distributed, so there will be no
unnecessary delay. The number and distribution of
the vessels will depend, as already stated, upon the con-
dition of the mill and the severity of the attack. It is
best to begin with the lowest story and work upward.
The operators can then keep above the settling gas.
When the bisulphid has been applied throughout the
mill it should be locked and kept closed until the fol-
lowing Monday morning. All windows and doors
should then be thrown wide open and the building
allowed to air an hour or more before fire is started in
it. Where the building is large and a great quantity
of material has been used, it is wise to have a watch-
man stationed outside to prevent any one from entering
or loitering about the building during fumigation.

Practical application. — As a guide to those who may
use this method, I quote several letters from practical
millers who have used carbon bisulphid successfully.
The superintendent of a large Pennsylvania milling
company, whose name I withhold by request, wrote me

272 FUMIGATION METHODS

the following letter. • It is a valuable contribution, and
should be read by every wide-awake miller and grain-
dealer : ' * We have delayed answering your valued
letter until we were able to report the result of our
efforts to destroy the weevils in our mill. Following
the line of your advice, we ran our stock down low and
thoroughly renovated our mill from" top to bottom,
cleaning all reels and purifiers. We then fumigated
the whole building with carbon bisulphid. We dis-
tributed 300 soup-plates about half filled with bisul-
phid through the mill, and saturated balls of cotton
with the same material and placed them in all the reels
and purifiers. We did this on Saturday night, closed the
mill tight and left the weevils to their destruction.

' * We opened the mill Monday morning and
thoroughly ventilated it before entering it. We found
we had destroyed thousands of the pests, and in the
reels and purifiers we had killed them all. In the
course of a few days a few insects began to show up in
the cracks in the floors and in dark corners. Two
weeks later we repeated the dose in the same manner
and obtained about the same results. In the mean
time we whitewashed the mill from top to bottom
(that is, every place that could be covered) , putting on a
good heavy coat. We have reduced the bugs to a very
small number, and eternal vigilance is the order of the
day with us.

' ' We are still fighting them. Our plan is to keep
a stock of bisulphid on> hand outside of the main build-
ing. We do not think it is advisable to store it in the
mill. Wherever we find a place infested by the weevil
we use it freely, taking care to do it when the mill is

FUMIGATION WITH CARBON BISULPHID 273

shut down and closed up tight. We find the best
results from the use of carbon bisulphid can be obtained
by spraying it on the floors and in infested places. We
think when placed in plates it does not evaporate quick
enough to produce the death atmosphere required."

Extra precautions. — The writer has called atten-
tion to the dangers from fire when the fumes of carbon
bisulphid are present. Special reference is now made
in connection with the treatment of buildings with this
gas. Not even a lighted cigar or pipe should be al-
lowed in the building. Always do the work in day-
light. No artificial lights of any kind are allowable.
Bven electric lights should not be used. When turn-
ing them on or off there is always danger of producing
a spark, which might prove disastrous. Heated steam-
pipes should be allowed to cool before the application is
made. Electric fans should not be run. There should
be no heat of any kind in the building while the vapor
is enclosed. Owners of adjoining premises should be
informed of the nature of the work being done and
cautioned to be on their guard during the hours of
fumigation.

Germination of seeds. — Fifty-four varieties of seeds,
including the principal grain and garden seeds, were
recently treated with carbon bisulphid by the Division
of Botany, United States Department of Agriculture.
Every precaution was taken to insure uniformity in
the seeds of each lot, treated and untreated. The
treated lots were exposed to an atmosphere saturated
with carbon bisulphid vapor for forty-eight hours.
Under the most extreme treatment, the severity of

274 FUMIGATION METHODS

which would never»be equaled in ordinary practice, a
majority of the varieties tested showed no injury and
germination was practically, the same in each lot.
Seeds of the grass family appeared more tender than
other kinds. Experiments were also conducted upon
grain in bulk, using the liquid at the rate of one pound
to 100 bushels of grain. The exposure lasted twenty-
four hours. No injury could be detected in even the
most delicate seeds.

Treating seed and grain in bulk. — Such seeds as
corn, wheat, rice, peas, beans, cow-peas, and others
are frequently attacked by insects and seriously injured
or entirely destroyed. No insecticide now known is
equal to carbon bisulphid for the destruction of such
pests. Seeds or grains to be fumigated should be placed
in barrels, bins, or rooms. The enclosure should be
tight. Apply the carbon bisulphid as directed above,
at the rate of from one to one and a half pounds for
each 1,000 cubic feet of space. A bin or room ten feet
each way, or 1,000 cubic feet, will hold about 100
bushels of grain. A barrel or small enclosure will
require a larger proportional amount unless it is very
tight. Place the liquid on top of the seed in shallow
vessels. A small bin or barrel should be covered with
heavy blankets to better retain the vapor. Close
the receptacle for 24 or 36 hours. The germinating
power of the seed will not be injured in the least, other
conditions being normal. Rye, millet, barley, and
crimson clover are the most liable to injury and should
receive proportionately a less amount.

As many of these pests enter the seeds in the open
field while the grain is in shock, stack, or growing, it is

FUMIGATION WITH CARBON BISULPHID 275

desirable to fumigate large bulks of grain, etc. , a.s soon
as possible after it is put in store. This is especially
true of wheat, corn, peas, and beans, particularly those
to be used for propagating purposes later. L,arger
warehouses or granaries can be successfully treated if
the directions cited above are followed. With large
bulks of grain the vapor may be left for two or three
days, or even longer.

Stimulating effects on plants. — It is an acknowledged
fact that the growth of plants on soil following treat-
ment is unusually good. Treatment of a corn-field
yielded an increase of 46.8 per cent, in the grain and
21.73 Per cent, in the stover. Potatoes showed an
increase in weight, varying from 5.3 per cent, to 38.7
per cent. In a series of experiments upon corn, oats,
beets, potatoes, and clover, much the same results
were obtained, but the most marked increase was in
the clover. It was found that the vapor was not
detrimental to the active bacteria causing the nodules
upon the roots of this legume, but rather seemed to
favor their multiplication. Furthermore, it was found
upon these same plats that the beneficent influence of
the treatment was quite apparent the following year,
though less marked than it had been the first year.

EffeEl upon fruit. — Recently an Italian investigator,
M. F. Sestini, has determined the effect of carbon bi-
sulphid upon fresh fruits. His conclusions are as fol-
lows: One volume of carbon bisulphid evaporated in
10,000 volumes of air produces no alteration in the
character of the fruit during an exposure of twenty-
four hours. After the treatment flavor is normal and

276 FUMIGATION METHODS

it appears that the perfume of each fruit gains in fine-
ness and intensity. The color of fruits not entirely
sound becomes deeper, especially upon those parts of
their surfaces which have been bruised during ripening
or from defects in packing ; it is thus very easy to
choose carefully, rejecting such fruit as could not have
been preserved.

Woolens, furs, and clothes. — Woolens, furs, and
other wearing apparel may be placed in a tight, paper-
lined trunk or a large box, and treated with carbon
bisulphid. When stored away, place a shallow dish
holding a few ounces of the liquid on the goods, and
spread some newspapers over the top and close.
No further attention will be required ; but if the box
is not tight, it will be necessary to repeat the dose
every few weeks during the hot weather. An excel-
lent plan is to provide a large packing-chest having a
close-fitting cover. By boring a hole through the
cover and fastening a small sponge or bit of cotton-
waste inside, it may be fumigated by pouring the bi-
sulphid through the hole upon the absorbent when it
is necessary. Carpets, rugs, robes, etc., can be freed
of all pests if fumigated for a few days in such a box.
The odor is less persistent in the goods than that of
moth balls, tarred paper, or other materials. When
used on fine fabrics it will not stain or injure the most
delicate articles, provided the pure carbon bisulphid is
gotten.

Such household pests as cockroaches, fish moths,
bedbugs, fleas, carpet-beetles, etc., can be destroyed
in tight rooms by a liberal application of carbon bisul-

FUMIGATION WITH CARBON BISULPHID 277

phid. Frequently the holds of ships are cleared of pests
in this manner. The liquid is quite generally used for
the destruction of a number of insects commonly called
museum pests. When specimens are inclosed in fairly
tight showcases or trays, they can be easily treated in
the cabinet or drawer. As a measure of safety, in
many museums the fumigation is done annually,
regardless of the absence or presence of the pests.

Killing prairie-dogs, gophers, squirrels, etc. — For
the destruction of small animals that burrow under
ground, such as prairie-dogs, gophers, woodchucks,
squirrels, moles, rats, mice, etc., nothing has been
used with such gratifying results as carbon bisulphid.
Some years ago, when the writer was located at the
University of Illinois, several plots of land on the
Experiment Station farm were overrun with gophers.
Their presence greatly interfered with the experiments
being conducted, and carbon bisulphid was used to
destroy them. The holes or burrows were located. A
piece of cotton about the size of a hen's egg was satu-
rated with the liquid, thrust into the hole, and closed
with a small piece of sod and loose dirt stamped down
firmly. A few hours later several of the burrows were
opened, and in every case a dead animal was found
with its nose thrust into the cotton. It evidently had
made an attempt to escape the deadly vapor.

Amount to use. — A pint of carbon bisulphid, a lit-
tle more than a pound, is sufficient to treat twenty
ordinary burrows. The amount used, however, de-
pends somewhat upon the size and character of the
burrow. If rather small and in a somewhat compact

278 FUMIGATION METHODS

soil, a small quantity will suffice ; but if the burrow is
large, rather shallow, and with several openings lead-
ing to the surface, much more liquid will be required.
As a rule, a small wad of cotton; wool, old rags, excel-
sior, even dry grass or a corn-cob, saturated with a
little less than one ounce of the liquid and heeled in
the holes, will do the work. A Nebraska farmer says
he uses dried balls of horse manure. They hold the
liquid well, are less expensive than cotton, and easily
obtained.

On the Laramie Experiment Farm in Wyoming
ninety -six burrows were treated during the month of
July. The applications were, with few exceptions,
made in the evening. The next day the treated bur-
rows were visited, and in no instance had the earth
which had been used for plugging the opening been
disturbed. A second and third visit to these burrows
found them securely plugged. In two instances some
animal, presumably a ground squirrel, had made an
effort to dig open the burrow from the outside. The
opening extended only to the ball of cotton, when, from
all appearances, the task was given up. In forty -three
instances gophers (squirrels) were driven or seen going
into the burrows and treated at once. None of the
animals ever again saw daylight.

It is best to perform the work in the evening, other-
wise some of the treated burrows will be dug open by
out-lying squirrels. The remedy can best be applied
in the spring, while the ground is yet compact. Where
the balls of dried horse-dung are used the cost is
reduced and the rounded masses carry the chemical
beyond the reach of the dirt used in closing the hole.

FUMIGATION WITH CARBON BISUUPHID 279

At the Idaho Experiment Station a test was made upon
thirty holes. Twenty-seven of these were undisturbed;
two were scratched open from the outside and one
from the inside. Several holes were afterward dug
open and in each was found a dead squirrel.

Expert opinions. — There have been many exagger-
ated reports about the nature of this chemical com-
pound. In this connection I can do no greater service
than to quote a letter from Edward R. Taylor, the
leading manufacturer of carbon bisulphid in this
country. He says : "I have seen a great many very
random statements on the subject of the inflamma-
bility of carbon bisulphid. One says, ' Use the same
care as with gunpowder ' ; another says, ' it is a very
explosive liquid.' These are both very misleading
statements with reference to its properties. I have
quoted the statements, however, in my printed matter
for the reason that farmers and many others use the
goods, and will be sufficiently startled by such state-
ments to be careful and have no light or fire about.

' ' Nearly everybody is now familiar with gasoline.
The properties of that liquid and carbon bisulphid are
practically identical, in that both are inflammable but
neither of them explosive. The vapor of either of
them mixed with air is explosive, but the liquids are
not explosive. I have shipped thousands of pounds
of bisulphid to millers, elevator operators, and farmers,
and have yet to have the first report of any disaster,
even of the most trivial character. Need I say more ?
My directions are explicit. Do the work Saturday
afternoon by daylight. Have absolutely no light or
fire of any kind about. Close the building and leave

28O FUMIGATION METHODS

the bugs to their c^estrudlion till Monday morning,
Then open doors and windows, and thoroughly venti-
late before going to work."

The vapor of carbon bisulphid takes fire in air at
about 300° F. and burns with a faint blue flame, diffi-
cultly visible in daylight, but evolving considerable
heat and decomposing the carbon bisulphid into carbon
dioxide (CO,) and sulphur dioxide (SO2). The latter
is the familiar gas given off by the burning of sulphur
matches and is a strongly poisonous, suffocating gas
which should not be inhaled. Carbon bisulphid vapor
mixed with three times its volume of oxygen, or an
amount of air containing that amount of oxygen, forms
a mixture which is very highly explosive upon ignition.
As 21 per cent, of the air is oxygen, one volume of
liquid carbon bisulphid evaporated in 5,357 volumes of
air would form such a mixture. An atmosphere com-
posed of one volume of carbon bisulphid vapor to
approximately 14.3 volumes of air is liable to violent
explosion in the presence of fire of any kind whatever,
or a temperature of about 300° F. without flame. We
have here about the maximum danger-point from
explosion in the use of carbon bisulphid.

Exterminating the flour moth. — My experience with
the Mediterranean flour moth is of nearly seven years'
standing. Until I took charge of my mill six years
ago I had never seen nor heard of the insect, and when
I found it here and learned what it was I doubted
whether such a delicate little creature could do any
more harm than a house-fly. I soon had evidence,
however, of its capacity for mischief. For one day it

FUMIGATION WITH CARBON BISULPHID 28 1

actually succeeded in shutting down our 100 h. p. en-
gine by so choking conveyors, elevators, etc. , with its
webs that the wheels simply could not turn. This is
an absolute fadl. Meanwhile I had written to Prof.
W. G. Johnson, the expert, about the pest and sent
him a sample of its work. When the mill was finally
choked to a standstill I knew what to do: I first put
six men at work taking spouts and elevator legs apart
and cleaning them thoroughly, and when that was
done I had them go for the machines. It took us just
six days to get cleaned up. Under the Professor's
advice I had provided ten gallons of carbon bisulphid
and about 200 tin pie-plates. Saturday afternoon we
closed and packed all the doors and windows, distrib-
uted the plates throughout the mill, filled them with
bisulphid, and "let her simmer " until Monday morn-
ing. Opening up the mill we found dead moths every-
where.— L. C. SCHROEDER, New York.

Some insurance companies were a little uneasy lest
they should suffer loss by fire originating from the
use of carbon bisulphid in mills. The American
Miller investigated this subject by sending letters of
inquiry to all the important millers' insurance com-
panies in the United States and Canada, and did not
learn of a single fire known to have been caused by
the use of carbon bisulphid. The properties of the fluid
have been fully described above, and millers have been
warned to keep lights and fire away from the vapor,
lest an explosion should occur. The fact that it has
been used so long without fires being traceable to it
gives strength to the opinion that millers, out of con-
sideration for their own lives, have heeded the warning

282 FUMIGATION METHODS

and have been exceedingly careful in applying it. It
should not be stored near the mill, as this increases the
fire risk. A break in the can or drum might unex-
pectedly release fumes which would soon fill the mill.
Death to weevils. — Carbon bisulphid settled the
weevil family in our mill. It was so full of them we
thought we would have to abandon it for a time. Bi-
sulphid cleaned them out and saved us. — A. Wii,-
HEiyM, Ohio.

All a miller wants for weevils and other mill pests is
" Fuma " carbon bisulphid. It knocked them out for
us. — J. C. BRIGHT & SON, West Virginia.

Exterminating moles. — When there were indications
of moles to be seen, we found the run, and inserted a
ball of cotton thoroughly saturated with * ' Fuma ' ' in
each opening. The earth was firmly packed over the
opening. As these little animals have so many turns
to their paths, I followed the run and put in eight more
well-saturated cotton balls, always being careful to
pack the earth firmly over the opening. Anything
worth doing at all is worth doing well. We were
about discouraged, as the moles were fast destroying a
lawn we were anxious to save. We determined to
give " Fuma " a trial, and am glad we did, as we were
soon rid of moles. — A. B. SWAN, Long Island.

Destroying woodchucks. — I have always had my
share of woodchucks, and I never could get rid of them
until last season. I got an ounce of carbon bisulphid,
used one-half on three burrows, and in about three
hours all three had been dug out. I used the other
half where an old one had young; the next morning I

FUMIGATION WITH CARBON BISULPHID 283

dug out the hole and found them dead. A neighbor
joined with me and we got twenty pounds of carbon
bisulphid. One pound is enough for fifty, and not one
has ever dug out of the hundreds that we have treated,
unless there was some opening that we missed. Pour
from one to two spoonfuls on anything that will absorb
the stuff, push it into the hole three feet, push down a
sod nearly to it, hoe on earth and tramp down. Treat
all main outlets the same, and next summer one will
be puzzled to find the place. — A. B. JOHNSON, New

York.

Destruction to prairie- dogs. — I cleared a pasture of
eighty acres with fifty pounds of carbon bisulphid and
not a dog showed up all summer. Five or six came
from another town late in the fall, but I soon put them
to sleep and they have not waked up yet. It is the
cheapest means by which prairie dogs can be destroyed.

—THOMAS SHEFFRAY, Nebraska.

I have destroyed the prairie-dogs on about eighty
acres at a cost of $30. This one operation increased
the value of the land $500. One pound of of carbon
bisulphid will treat twenty-five holes. — ISAIAH L,IGHT-
NER, Platte County ', Nebraska.

We killed the prairie-dogs on about a hundred
acres with five gallons of carbon bisulphid. It is
the best, as well as the cheapest, way of getting rid of
them. — Kansas Farmer.

Rats and mice easily destroyed. — Some years ago the
writer's attention was called to a granery in Maryland,
under which a large number of rats had burrowed into
the ground. The building was double, set on posts

284 FUMIGATION METHODS

raised about eighteen tnches above the ground, with a
driveway between. The earth underneath was com-
pletely honeycombed with burrows. Two pounds of
carbon bisulphid were secured. Wads of cotton, vary-
ing in size from a hen's egg to one's fist, were saturated
and thrust into every burrow that opened on the sur-
face. The holes were securely closed. Only in two
instances were the holes opened by their occupants,
and these were quickly destroyed by a second dose.
Wherever a burrow is found about any building it can
be treated in the same way.

In fields where rats and mice frequently do serious
injury to corn and other grain in shock they can be de-
stroyed by saturating a small wad of corn-silk or husks
and pushing them in the holes after the shock has been
overturned. Frequently cellars and root-houses are
infested with rats. A few ounces of carbon bisulphid
used as indicated will exterminate them.

How carbon bisulphid is put up. — This material is
usually put up in steel drums holding fifty pounds
each and costs about ten cents a pound. It can be
purchased from local dealers in smaller quantities. In
such cases the price is about double that quoted, or
even more. The grade known as Fuma carbon bisul-
phid is cheaper than the chemically pure article. Only
in rare cases is it necessary to use the pure bisulphid.
For general insecticide purposes ' ' Fuma ' ' is the
standard and entirely satisfactory. The writer has
used large quantities of it with most excellent results
in every case.

CHAPTER XXII

LAWS REGULATING NURSERY AND ORCHARD
INSPECTION AND FUMIGATION

>R many years California has been protecting
her horticultural interests by strictly en-
forcing laws enacted for that purpose. That
State was the pioneer in this movement, and
the benefits arising therefrom have been very marked.
Not only have California orchards been greatly in-
creased in area, but many dangerous insect pests and
diseases have been kept out by the vigilance of the
quarantine officers. With the invasion of the San
Jose scale in the Eastern States, various local laws
have been passed to meet conditions prevailing in
many states or territories.

In Maryland, Delaware, and Canada the fumiga-
tion of all nursery stock with hydrocyanic acid gas is
required. North Carolina has recently adopted fumi-
gation methods, and nurserymen in that State will be
required to fumigate all trees offered for sale. In
New York and Montana the inspection laws require
fumigation of all nursery stock if thought necessary.
In Oregon all apple, pear, or other stock grown on
apple roots must be fumigated before delivery. Con-
ditions are such that other states will soon be obliged
to incorporate in their laws the fumigation require-

285

286 FUMIGATION METHODS

ment with rules regulating the inspection of nurseries.
Maryland has done more in perfecting fumigation
methods in the East than any other State. The
Canadian government practically adopted the Maryland
system, after sending a representative to familiarize
himself with details and methods used in that State.

The following states and territories have no laws at
present, December i, 1901, governing the transporta-
tion or inspection of nursery stock : Alaska, Alabama,
Arizona, Arkansas, Kansas, Maine, Minnesota, Missis-
sippi, Nebraska, Nevada, New Hampshire, Oklahoma,
Rhode Island, South Dakota, Texas, Vermont, and
Wyoming. If special information is desired relative
to inspection or the shipment of nursery stock into
any of the above states or territories, it can be secured
through the Directors of Experiment Stations.

A brief synopsis of the horticultural laws and
rulings regulating the inspection of nurseries and
orchards, and the shipment of nursery stock in the
various states and territories is given herewith. Most
states require copies of the authorized certificate of
inspection to accompany and be attached to each con-
signment of nursery stock. Oregon, Colorado, Idaho,
and Montana require all nursery stock entering their
borders to be inspected by local inspectors. Canada
receives no stock, as noted in Chapter XXIII., except
through certain ports of entry, where it is fumigated.
This is true also in Montana and Oregon. All stock
shipped into New York from other states must be
fumigated. Nurserymen desiring to ship into those
states should bear this in mind and look up the points
of entry. Duplicate certificates are required for ship-

INSPECTION AND FUMIGATION LAWS 287

merit of nursery stock into Georgia, Michigan, Ohio,
North Carolina, South Carolina, and Virginia.

California. — The State Quarantine Officer at San
Francisco, Cal., must be notified of the receipt of nurs-
ery stock, pits, fruits or vegetables, which must beheld
for inspection. Any consignment found infested with
injurious insects or plant diseases shall be treated under
the direction of the quarantine officer. If the ship-
ment is found to contain pests not established in the
State, the entire consignment shall be destroyed or
sent out of the State. Any nursery stock affected by
yellows or rosette will be destroyed or returned to the
consignee. The county boards of horticulture cause
the inspection of nurseries, orchards, vegetables, vines,
and fruits. Owners are obliged to suppress injurious
insect pests if found on their premises.

Colorado. — The regulations for the prevention of
diseases in orchards and nurseries are placed in the
hands of the State Board of Horticulture. County
inspectors are appointed, and they must examine all
shipments of nursery stock before delivery. If found
infested, they shall be disinfected, destroyed, or re-
moved from the county, at the option of the inspector.
An orchard, nursery, fruit-packing house or storeroom
found infested with injurious insect pests or diseases
dangerous to fruit trees, vines, or the horticultural in-
terests in general, must be disinfected or treated ac-
cording to the direction of the county inspector. If
he shall neglect or refuse to treat or destroy as directed,
the owner shall be guilty of maintaining a nuisance,
and liable to a fine. If found guilty, the inspector has

288 FUMIGATION METHODS

a right to abate the jiuisance at the expense of the
owner.

Connecticut. — The State Entomologist, who shall
have an office at the Experiment Station at New
Haven, Conn., under the direction of the Board of
Control of the Connecticut Agricultural Experiment
Station, has charge of the nursery and orchard inspec-
tion in that State. All nursery stock shipped from
other states, counties, or provinces shall bear a certifi-
cate. In case a shipment is made not bearing a cer-
tificate, it can be inspected by the State Entomologist
at the request of the owner, and if found free from
pests and disease it may be received, and the cost of
inspection deducted from the consignor's bill for said
stock. All nurseries in the State shall be inspected at
least once a year, and if no serious pests are found a
certificate to that effect is given to the owner. If pests
of a dangerous character are discovered, the owner is
required to suppress the same under the direction of
the State Entomologist. This act went into effect
July i, 1901.

Delaware. — The orchards and nurseries of the State
must be inspected at least once a year by the inspector
authorized by the State Board of Agriculture at Dover,
Del. Nursery stock shipped into the State must be
accompanied by a certificate. Since August i, 1901,
nurserymen are required to fumigate all stock offered
for sale or shipment.

Florida. — A penalty for knowingly selling diseased
nursery stock is provided by the statutes, but they are
inoperative. The Entomologist at the Experiment

INSPECTION AND FUMIGATION LAWS 289

Station at Lake City, Fla., issues certificates to
nurserymen in the State upon request.

Georgia. — A State Entomologist is appointed by
the State Board of Entomology, with headquarters at
Atlanta, Ga. The Board formulates rules for the
treatment or destruction ot trees, and prevent whenever
possible the introduction of any pests considered
dangerous to the horticultural interests. A certificate
from the State Entomologist must accompany all stock
shipped by nurserymen of the State. Nurserymen
from other places desiring to ship into Georgia must
file a copy of their accredited certificate of inspection
with the Commissioner of Agriculture at Atlanta, Ga.
When the proper certificate is filed by nurserymen from
without the State, the State Board of Entomology will
issue its certificate permitting shipment of stock into
the State. Official tags, bearing a facsimile of this
certificate, are required and will be furnished by the
Board at cost, viz. : Fifty cents for the first one .hundred
and twenty-five cents for each additional hundred.

Idaho. — A general State inspector and ten district
inspectors are appointed by the State Board of Hor-
ticulture at Moscow. These officials are required to
inspect orchards, fruit houses, etc. , and if pests of a
dangerous nature are found the premises may be dis-
infected or the fruit may be destroyed, at the option of
the officer in charge. Peach, nectarine, apricot, plum,
almond and other trees budded or grafted on peach
stock grown in districts where peach yellows or peach
rosette are known to exist are prohibited sale or dis-
tribution in the State. All nursery stock offered for

2 QO FUMIGATION METHODS

sale from other sources must be examined by the in-
spector, and if not approved it must be destroyed. To
all shipments of nursery stock intended for the State
shall be affixed a label showing the contents, together
with the name of the shipper and the locality where
the stock was gro\vn.

Illinois. — The State Entomologist, whose office is
at Urbana, 111., has full charge of the nursery and
orchard inspection. Nurseries are inspected annually
and certificates granted, copies of which must accom-
pany all shipments. It is unlawful for transportation
companies to deliver nursery stock of any kind within
the State unless such stock is accompanied by a certi-
fied certificate approved by the State Kntomologist.

Indiana. — All the nurseries of the State shall be
inspected at least once a year by the State Entomolo-
gist, whose office is at Lafayette, Ind. Certificates
of inspection are given to nurserymen within the State,
and copies of the same must accompany all shipments.
All stock received from other states must bear a cer-
tificate signed by State or government inspectors.

Iowa. — Quarantine maybe established against dan-
gerous insects and plant diseases by the State Ento-
mologist at Ames, la. Nurseries are inspected at least
once a year and certificates issued accordingly. It is
unlawful to bring nursery stock into the State unless
accompanied by proper certificate from an authorized
official.

Kentucky. — The nurseries of the State are inspected
at least once a year by the State Entomologist at Lex-

INSPECTION AND FUMIGATION LAWS 29!

ington, Ky. Certificates are issued when the stock
is found in good condition, and whenever a nurseryman
sells trees, vines, plants, or other nursery stock, he
shall attach to each package a certificate signed by
himself, stating that the contents has been examined
by a properly certified official and found free from San
Jose scale and other destructive and injurious insect
pests or fungus diseases. All stock shipped into the
State must be plainly labeled with the name of the
consignor and the consignee by the State or govern-
ment inspector. Stock arriving without certificate
shall be returned to the consignor or inspected by the
State Entomologist at the expense of the consignor;
otherwise it will be burned.

Louisiana. — It is unlawful to bring into the State
nursery stock, pits or any kind of fruit infested with
disease or insects of an injurious nature. It is unlaw-
ful to propagate or offer for sale any such stock. All
fruit trees and other nursery stock brought into the
State shall be labeled with the name of the owner or
grower, the locality where grown, and shall be subject
to inspection by the Entomologist of the Experiment
Station at Baton Rouge, La. It is the duty of the
owner to disinfect or destroy any fruit trees perniciously
affected with disease.

Maryland. — Co-operating under the laws creating a
State Horticultural Department, the State Entomolo-
gist and State Pathologist are required to inspect once
every six months all nurseries within the State and
issue certificates to the owners. All nursery stock
shipped must be accompanied by a printed copy of the

2Q2 FUMIGATION METHODS

official certificate attached to each package. Nurseries
are compelled to fumigate with hydrocyanic acid gas
all stock grown or handled by them under the direction
of the State officers. Every package of nursery stock
shipped into the State must be plainly labeled with the
name of the consignor and consignee and a certificate
showing that the contents has been inspected by the
proper official. Transportation companies receiving
nursery stock arriving into the State without such
certificate must send notice to the inspectors at College
Park, Md. Failure to return a shipment not properly
certified renders the stock liable to seizure and destruc-
tion by burning.

Massachusetts, — The Trustees of the Agricultural
College at Amherst, Mass. , have appointed two inspec-
tors, who inspect all nurseries within the State when
called upon to do so. All certificates expire July i
following the date of issue.

Michigan. — The State Inspector of nurseries and
orchards is appointed by the State Board of Agricul-
ture, Lansing, Mich. All orchards and nurseries of
the State are properly inspected and certified and cer-
tificates issued to the latter. All persons growing or
offering for sale any nursery stock within the State are
obliged to apply to the State Board of Agriculture and
request inspection before August i of each year. A
deposit fee of $5.00 as a license is required, the license
being good for one year and not transferable. Any
person, firm or corporation resident of another State
shall not engage in the business of selling nursery
within the State without first having a proper license

INSPECTION AND FUMIGATION LAWS 293

from the State Board. A bond in the sumof$i,ooo is
required on condition that nurserymen and dealers
will comply with all the provisions of the law, and
upon demand will file with the Board a list of the per-
sons to whom they have sold or delivered any nursery
stock, giving the species, together with the address of
each purchaser. Failure on the part of any nursery-
man, grower, agent or dealer to comply with these
provisions shall render him liable to a fine.

Missouri. — An inspector is appointed, whose duty
it is to visit sections of the State and prescribe reme-
dies for diseased trees and orchards. Nursery stock
arriving from without the State must be accompanied
by the entomologist's certificate, and no package can
be delivered until such certificate is attached. The
work is under the general direction of the State Board
of Agriculture, Columbia, Mo.

Montana. — The State Board of Horticulture shall
appoint an inspector of fruit pests for each of the six
districts. The nurseries, orchards, fruits, etc., shall
be visited regularly and the regulations of the Board
enforced. Every person selling or delivering nursery
stock is required to notify the inspector at least five
days before the said stock is to be delivered, giving
date and the nursery and railroad station where the
said stock is to be delivered. It shall be the duty of
the inspector to inspect such stock, and if any of it is
found infested or diseased to order its destruction.

Under the ruling of the Board of the Inspectors at
large, inspectors shall inspect or fumigate all nursery
stock growing in the State, and shall have authority

294 FUMIGATION METHODS

to order all nursery »stock fumigated with hydrocy-
anic acid gas or other method. All stock shipped
into the State before delivery to the purchaser must
be inspected and fumigated as follows : Consignment
over the Northern Pacific R. R. from the West, in-
spected and fumigated at Missoula; over the Oregon
Short Line from the South, at Dillon; over the North-
ern Pacific R. R. from the East, and over the Burling-
ton railway, at Miles City or Billings; over the Great
Northern, at Kalispall; over the Great Falls and Can-
ada Railway, and from the East over the Great North-
ern Railway, at either Glasgow, Chinook, Fort Bentori
or Great Falls. Any nursery stock brought in on
wagons or otherwise shall be inspected and fumigated
at the nearest quarantine station.

Importers of nursery stock may have an inspection
at any point in the State by paying the expense
thereof. All boxes, packages, or wrappings used in
importing nursery stock shall be burned as soon as
emptied. A fee of $10 shall be charged for each car
load to cover the cost of inspection and fumigation.
All green or citrus fruits offered for sale in the State
shall be inspected, and if found free of disease and
infection shall be branded ' ' Inspected and passed. ' '
If infested they shall be burned. A fee of two cents
per box, with a maximum fee of $5 for each lot in-
spected, shall be exacted. Every person offering to
sell or deliver nursery stock in the State shall place on
each package, or car, a label stating whether or not
the stock was grown in Montana. General informa-
tion can be secured from the Secretary of the State
Board of Horticulture, Missoula, Mont.

INSPECTION AND FUMIGATION LAWS 295

New Jersey. — Any nurseryman or grower of plants
offered for sale may require the State Entomologist
at New Brunswick, N. J. , to examine or have examined
the stock grown by him. If no injurious insects liable
to spread are discovered he may demand a certificate to
that effect. All nursery stock shipped into the State
must be accompanied by a proper certificate. Any
stock received without a certificate may be detained by
the State Entomologist or his deputy, and in case it is
found infested it may be destroyed or reshipped to the
original shipper. Florists' stock is exempt under this
act. Not more than three commissioners are appointed
for each county. They are empowered to report the
presence of any injurious insects or diseases liable to
spread to the State Entomologist, who may order such
treatment as seems best. Persons failing to carry out
the instructions of the State Entomologist shall be
fined.

New York. — The orchards and nurseries of the State
are inspected annually under the direction of the Com-
missioner of Agriculture, Albany, N. Y. Prior to the
first of September each year every nursery or other1
place where trees, shrubs, or plants, commonly known
as nursery stock, are grown for sale must be inspected
and proper certificates issued to the owner. All
nursery stock transported in any manner shall be
accompanied by a copy of said certificate attached to
each car, box, bale, or package. All transportation
companies within the State receiving or carrying
nursery stock from any point without the State to any
point within shall immediately upon receipt of such
consignment notify the Commissioner of Agriculture,

296 FUMIGATION METHODS

giving the name of the consignor, the consignee, and
the point of destination.

If in the judgment of the Commissioner of Agri-
culture, or his representative, the consignment should
be entirely destroyed, such destruction shall be carried
on and completed under the supervision of the person
in charge. The commissioner shall notify the owner
of the trees immediately, giving a brief statement of the
facts, and calling attention to the law under which it
is proposed to destroy them. In case of objection
to the findings of the inspector or agent of the Com-
missioner of Agriculture, an appeal shall be made to
such commissioner, whose decision shall be final. An
appeal must be taken within three days from service
of said notice and shall act as a stay of proceedings
until it is heard and decided.

The recent law passed by the New York Legisla-
ture, 1902, requires the fumigation of all nursery stock
coming into the State from other States. When fumi-
gated by the consignor a certificate should be attached
indicating same. All nurseries within the State located
within one-half mile of a district infested with the San
Jose scale must fumigate all their nursery stock before
shipment or distribution.

North Carolina. — No person shall sell or give away
any trees, shrubs, or woody vines until a license to
deal in such plants has been previously obtained from
the Commission Controlling Crop Pests at Raleigh,
N. C. Certificates previously certified must accom-
pany all consignments of nursery stock, and transpor-
tation companies shall not deliver any such stock
unless a certificate is attached to each package. All

INSPECTION AND FUMIGATION LAWS 297

nursery stock not properly labeled may be seized or
destroyed. Transportation companies having nursery
stock in their possession not properly labeled or certi-
fied shall destroy it or send it out of the State within
forty-eight hours, if brought from without the State or
otherwise. All licenses to sell nursery stock issued by
the commissioner shall bear a uniform date, April ist
or October ist, and shall be good for six months and
no longer.

Licenses to dealers shall be granted to residents of
the State, who shall sign an agreement not to purchase
nursery stock of any nursery or dealer located within
or without the State unless such a nursery is already
licensed by the commissioner. Licenses shall be
granted only to agents employed by licensed nurseries
or dealers, and the principals shall be held responsible
for the stock sold by such agents. No fees are charged
for licenses, but nurserymen and dealers will be required
to pay the actual traveling expenses of the State Ento-
mologist who is sent semi-annually to inspect their
establishments. Nurserymen outside the State must
send their official certificates properly certified to the
Department of Agriculture, Raleigh, N. C. One
hundred official tags will be furnished free of charge
to the nurserymen filing certificates. Additional tags
will cost forty cents per hundred. One of these tags
must be attached to each consignment of nursery stock
shipped into the State.

Ohio. — Not later than August 15 all nurseries in
the State shall be examined annually by the Inspector
or his representative appointed by the Agricultural
Experiment Station at Wooster, Ohio. If the nurser-

298 . FUMIGATION METHODS

ies appear free from, dangerous diseases and insect
pests, the inspector shall give each owner of the nurs-
ery a certificate to that effect on receipt of $10 for the
first day's inspection, and $5 for each subsequent day.
Copies of said certificate must accompany all ship-
ments of nursery stock. Bvery package of nursery
stock shipped into the State must be accompanied by
a copy of the official inspection certificate. Transpor-
tation companies are required to report to the Inspec-
tor of a consignment not properly certified.

Oregon.— The State is divided into five quarantine
districts by the State Board of Horticulture. All con-
signments of nursery stock arriving from without the
State must be inspected on arrival at the quarantine
station. If such stock is found free from pests or dis-
eases, the officer in charge shall issue a certificate to
that effect. If any trees are found infested, they are
to be disinfected and remain in quarantine until pro-
nounced clean. No peach, nectarine, apricot, plum or
almond trees, or other stock worked on peach roots, or
pits or cuttings, buds or scions of such-named trees
grown in the district where yellows or rosette are
known to exist, shall be admitted into the State.

All nursery stock from foreign countries found in-
fested with insects or diseases hitherto unknown in the
State are not allowed to land. Nursery stock may be
disinfected by dipping into a solution of whale oil soap,
or fumigated with hydrocyanic acid gas. All nurseries
must be inspected by the quarantine officers of the dis-
trict in the months of September, October, or Novem-
ber prior to shipment each year. Certificates shall be
issued where the stock is found in proper condition,

INSPECTION AND FUMIGATION LAWS 299

provided the owner shall fumigate with hydrocyanic
acid gas all pear and apple trees, or other stock grown
on apple roots after digging and before delivery. Gen-
eral information regarding the control of apple pests
may be had by addressing the State Board of Horticul-
ture, Salem, Oregon.

Pennsylvania.. — The Secretary of Agriculture at
Harrisburg, Pa., shall have all nurseries within the
State examined each year. If found free from dan-
gerous insect pests and other diseases, the owner shall
receive a certificate. Nurserymen receiving such cer-
tificate must attach a copy to each package of nursery
stock shipped. Transportation companies shall reject
stock not accompanied by such certificate. Nursery
stock shipped into the State shall be plainly labeled
with the name of the consignor and the consignee, and
a certificate showing that the contents have been in-
spected by State or government officers. Greenhouse
stock is exempt under the provision of this law.

South Carolina. — The Board of Trustees of Clem-
son College designates, every two years, three of their
members who constitute the State Board of Entomol-
ogy. This Board has full power to adopt rules and
regulations governing the inspection, certification, sale,
transportation, and introduction of nursery stock.
The Entomologist at Clemson College, (P. O.), S. C.,
shall direct the work and inspect each nursery in the
State during the months of August and September of
each year. Infested orchards shall be treated when-
ever discovered. The owners of infested orchards or
nurseries shall pay all cost for such treatment, except

3OO FUMIGATION METHODS

the traveling and incidental expenses of the entomol-
ogist. All nurserymen and dealers in nursery stock
located and doing business within the State limits are
required to accompany all stock with a copy of the
official certificate issued them by the inspector. All
certificates are invalid after June i of each year, but
must be renewed before October i of the same year.
All persons or incorporations without the State who
desire to sell nursery stock in South Carolina shall
register their name and file a copy of their certificate of
inspection with the Chairman of the Board of Ento-
mology. Upon failure to comply with this, shipments
may be destroyed.

Tennessee. — Nursery stock cannot be oifered for
sale in Tennessee without a certificate from the State
Entomologist being attached to each package, as well
as the name of the consignor and consignee. Certifi-
cates are valid twelve months from date of issue. It
is the duty of the State Entomologist to inspect all
nurseries and floral establishments when he deems it
necessary. All infested nursery stock must be de-
stroyed. Consignments of nursery stock from other
States shipped into Tennessee must bear certificates of
inspection, as well as the name of the consignor and
consignee. Unless a certificate is attached the trans-
portation company receiving same must notify the
State Entomologist at Nashville. A fee of $5.00 is
required from florists and nurserymen who have less
than fifty acres; the inspection fee is $10.00 for nur-
series over fifty and less than one hundred acres, and
$15.00 for more than one hundred acres. In effect
April 20, 1901.

INSPECTION AND FUMIGATION LAWS 301

Utah. — The State Board of Horticulture consists
of three members, each representing a district. It is
the duty of every owner of an orchard, vineyard, or
nursery to disinfect trees, vines, or nursery stock if
affected with any fruit-destroying disease. All per-
sons who make a general business of spraying trees
must first get a certificate from the Board. It is the
duty of the Board to have inspected all orchards and
nurseries within the State. All persons or nursery-
men shall report to the inspectors the receipt of any
trees from points outside of the State, and such inspec-
tors shall examine all such stock as well as stock
grown or offered for sale in the State. General infor-
mation can be secured from the State Board of Horti-
culture at Logan, Utah.

Virginia. — The rules regulating the inspection of
orchards and nurseries are made by the Board of Crop
Pest Commissioners. No person shall sell or trans-
port any fruit trees or other plants when infested with
woolly aphis, San Jose scale, peach yellows, black
knot of the plum, fire blight of the pear, or crown gall.
Any nursery found infested with these pests shall not
be entitled to a certificate until such pests have been
eliminated under the direction of the inspector. It is
unlawful for a nursery to offer for sale nursery stock
unless accompanied by a certificate of inspection. All
nursery stock entering the State from without must
be accompanied by a certificate from an official and a
competent inspector. The State Entomologist and
Pathologist at Blacksburg, Va., shall furnish to all
nurserymen in other states doing business in Virginia
an official tag upon request, if the certificate of inspec-

302 FUMIGATION METHODS

tion filed by said nurseryman from without is found
satisfactory. Transportation companies can not deliver
nursery stock, except when accompanied by a certifi-
cate of inspection and the official tag of the State
officer. All nursery premises must be inspected at
least once a year.

West Virginia. — All nurseries must be examined
once a year, not later than August i5th, by the
Director of the Agricultural Experiment Station of
Morgantown, or by his assistants. Nurserymen are
required to pay a fee of $10.00 for the first day's in-
spection, and $5.00 for each additional day required,
before a certificate is given. The certificate is void
after August i5th of the following year. Nurserymen
must also furnish transportation to and from railway
stations to their nurseries. Any person growing trees
for sale must apply to the Director for a certificate.
All orchards, gardens, and other premises where dan-
gerous pests are supposed to exist, must be examined
and given such treatment as may be deemed necessary.
All nursery stock from other States must be properly
certified, and plainly labeled with name of consignor
and consignee. In effect May 16, 1901.

Wisconsin. — The law in this State requires that all
nursery stock entering shall bear certificate showing
that it has been properly inspected, and is apparently
free from San Jose scale and other injurious insects or
plant diseases. The inspection is in charge of the
Agricultural Experiment Station at Madison, Wis.

CHAPTER XXIII

FOREIGN LAWS REGULATING SHIPMENTS OF
FRUITS AND NURSERY STOCK

T ""THERE have been so many laws enacted in for-
eign countries regulating the importation
from America of all plants commonly called
nursery stock, it is expedient to give briefly
an abstract of the regulations adopted by these coun-
tries. These statements will serve as a guide to nur-
serymen and others who contemplate exporting nursery
stock and other supplies.

Austria- Hungary. — By a decree April 20, 1898,
prohibits importation from America of living plants,
grafts and layers and fresh plant refuse of every kind
if on examination San Jose scale is found. It also in-
cludes the barrels, boxes, and other coverings in which
such goods or refuse may be packed. It embodies
fresh fruit and the refuse of fresh fruit, as well as the
packings which may cover the same. Admission lim-
ited to Bodenbach-Tetschen, Trieste and Fiume. Also
prohibits transit of infested goods through the Empire.
Belgium. — Importation and transit of fresh fruits,
living plants, and fresh parts of plants from the United
States can be made only by way of the ports of Ant-
werp, Ghent, and Ostende, upon production of a cer-
tificate from a competent authority asserting that
products are not infested by San Jose scale. If not
accompanied by certificate, the products can not be

303

304 FUMIGATION METHODS

delivered until inspected. If found infested they must
be destroyed with packings. The cost of all services
at the expense of the importer. This order went into
effect March 15, 1899, but does not apply to shipments
in direct transit by railway under supervision of custom
authorities.

British Columbia. — Rules and regulations, pub-
lished June 25, 1897, under the authority of the Hor-
ticultural Board Act, 1894, provide that all importers
of nursery stock, trees, plants, or fruit must give
notice upon arrival, and before removal from wharf or
station, to a member of the Board or to the Inspector
of Fruit Pests, who shall inspect the same and, if clean,
issue a certificate which shall be good for three months,
unless revoked by further inspection. Nursery stock
found to be infected shall be disinfected or destroyed.
Fruit found to be infected shall be destroyed or
reshipped.

Canada. — According to the San Jose scale act,
March. 18, 1898, Canada prohibits importation of nurs-
ery stock from the United States, Australia, Japan,
and Hawaii. Stock imported in violation of the law
will be destroyed, and the importer is liable to a pen-
alty of $200 for each offense, prescribed by Section 6
of Customs Tariff. The following exemptions are
made : Nursery stock of all kinds can be imported
from Europe without fumigation, as it is supposed the
San Jose scale has not gained a foothold in European
countries. Certain other plants, not liable to the
attack of the San Jose scale, are also exempted from
treatment under this act. These are: (i) green-

.FOREIGN LAWS REGULATING SHIPMENTS 305

house plants, including roses in leaf which have been
propagated under glass ; (2) herbaceous perennials,
including strawberry plants; (3) herbaceous bedding
plants; (4) all conifers; (5) bulbs and tubers.

As all vegetation is much earlier in Oregon and
Washington States, from which most shipments are
made into British Columbia, it has been arranged that
for that province the fumigating house shall be kept
open for the winter months from October 1 5 till March
15. For Manitoba and the Eastern Provinces the
spring season is from March 15 till May 15, and the
autumn season from October 7 till December 7.

These fumigating houses are located at the customs
ports of St. John, New Brunswick; St. John's, Que-
bec; Niagara Falls and Windsor, Ontario; Winnipeg,
Manitoba; and Vancouver, British Columbia. The
whole expense of these stations is assumed by the
Dominion Government, but all shipments are made
entirely at the risk of the shippers or consignees, the
government assuming no risk whatever. The pack-
ages must be addressed so as to enter Canada at one
of the above-named ports of entry, and the route by
which they are to be shipped clearly stated upon each.

Cape of Good Hope. — Regulations published March
25, 1896, under authority of act No. 9, dated 1896,
prohibits importation of any stone-fruit tree, or any
fruit, scion, cutting, graft, root, or seed, the growth
or produce thereof, from the United States, and any one
importing such article as aforesaid shall be subject to
a fine not exceeding £ 100 sterling or six months' im-
prisonment, and, in addition, the articles will be
destroyed. It is likely this will be modified, especially

306 FUMIGATION METHODS

for states in which "neither peach yellows nor peach
rosette exists.

France prohibits, decree of November 30, 1898,
entry into and passing through France of trees, shrubs,
products of nurseries, cuttings, and all other plants or
parts of living plants, as well as fresh debris from
them, from United States, directly or in storage, as
well as cases, sacks, etc. , used for packing. Also pro-
hibits fresh fruit and debris, when examination proves
presence of insect at entry into France.

GERMANY. — A decree of February 5, 1898, prohibits
importation of living plants and parts of living plants
from America, and barrels, boxes,etc. , used for packing.
Also fresh fruit or fresh parts of fruit when examina-
tion at port of entry shows presence of San Jose scale.
Imperial chancellor authorized to grant exceptions.

By commercial agreement July 10, 1900, this was
amended by annulling the regulation providing that
dried or evaporated fruits from the United States be
inspected. Such fruits are now admitted without
other charge than customs duties, and may be admitted
at the boundary at the following places:

Prussia. — Main customs offices at Eydtkuhen, Pil-
lau, Danzig, L,iebau, Aachen, inclusive of the customs
inspection office in the depot of Templerbend, and the
freight depot of Roth Erde ; Emmerich, inclusive of
the two steamship inspection offices, and the customs
inspection office located at that place; Kaldenkirchen,
inclusive of the customs inspection office at the depot
at that place; Geestemiinde, Flensburg, Hadersleben,
inclusive of the sub-customs office i Woyens; Kiel and

FOREIGN LAWS REGULATING SHIPMENTS 307

office at the depot in L,uxemberg. Also main tax
offices at Konigsberg i Pr. and Stettin, and subcustom
offices at i Oderberg, i Ziegenhals, i Halbstadt, i
Seidenberg, Herbesthal, Bentheim, Borken, and
Weener.

Bavaria. — Main customs offices at landau, Passau,
Simbach, and subcustoms office at Scharding a. Th.,
and Furth a. W. Also subcustoms offices at Kufstein,
Salzburg, Kger, Obernzell, and at the depot of
Kisenstein.

Kingdom of Saxony. — Main custom offices atZittau
and Schandau; subcustoms offices at Bodenbach and
Tetschen, Voitersreuth, Reitzenhain, and i Warnsdorf.

Wiirttemberg. — Main customs office at Friedrich-
shafen.

Baden. — Main customs offices at Konstanz, the
depots of Schafthausen and Waldshut, and at the depot
of Basel ; main tax office at Singen and Seckingen,
and subcustom office at Erzingen.

Oldenburg. — Subcustoms office at i Nordenham.
Liibeck. — Main customs house at L,iibeck.

Bremen. — Ports of entry at Bremen and Bremer-
haven.

Hamburg. — Quay office, Hamburg.

Alsace-Lorraine. — Subcustoms offices at Fentsch,
Amanweiler, Noveant, Chambrey, Deutsch-Avri-
court, Altmiinsterol, Basel, Markirch, Saales, Diedols-
hausen, and Urbis.

308 FUMIGATION METHODS

Netherlands. — By decree of May 23, 1899, prohibits
importation and transit, direct or indirct, of live trees
and shrubs, or live parts thereof, produced in America,
including boxes, casks, baskets, sacks, vessels, and
other articles used for packing, unless accompanied by
certificate issued by consular officer of Netherlands or
competent authority in port of shipment, and objects
shall not be landed unless certificate is satisfactory to
receiver of import duties.

The following exceptions are made: (i) Importa-
tions from countries bordering on the Netherlands in
which measures have been taken for combating the
San Jose scale; (2) importations for scientific purposes;
and (3) to meet requirements of frontier commerce.

New Zealand. — The act of 1896 prohibits impor-
tation of fruit of any kind infested with fruit-flies.
Fruit infested with codling moth will be destroyed
unless immediately reshipped. Fruit, plants, trees,
cuttings or buds infested with any scale insect will be
admitted only when accompanied by certificate. Other-
wise it will be fumigated at expense of importer or
destroyed.

Imported fruit admitted only at Bluff, Dunedin,
Christchurch, Wellington, and Auckland.

Live plants admitted only at Dunedin, Christchurch,
Wellington, and Auckland.

Fumigation performed only at Dunedin, Christ-
church, Wellington, and Auckland.

Switzerland. — Prohibits plants; prohibits importa-
tion of fresh fruit from America, except through
Customs Bureau at Basle, where it is subject to an
examination by an expert for San Jose scale or other

FOREIGN LAWS REGULATING SHIPMENTS 309

parasites. No restri(5lions to dire(5l importation of
dried fruits.

Turkey. — In 1899 it was stated that the imperial
government had decided to interdicl the importation
of trees, plants, and fruits coming from the United
States. The writer has made every effort to obtain
copies of the decree, but has been unable to secure
anything more definite than the above.

INDEX

PAGE

Actinic rays 6

Alkali action on 11

Apparatus, Orchard 27

Apple trees 16

Arkansas 229

Arizona 229

Bell tents 27,35

Black scale 80

Box, Fumigation 8, 96, 238

Brown scale 80

Buds 214

Building 165

Cabbage 150

Cacti 136

California 54, 223

Canada 229

Cantaloups 24

Cape Colony 211

Carbon bisulphid 153

Action in soils 263

Amount to use 266, 270, 277

Ants in lawns 268

Application, when 265

Borers in trees 269

Chemical properties 258

Clothes 276

Commercial uses 261

Diffusion 264

Effects on fruits 275

Extra precaution 273

Fidia viticida 268

First use 2, 257

Flour moth 280

France 262

Furs .- 276

Germination of seeds 273

Gophers 277

Ground moles 282

Household pests 276

How put up 284

In the arts 262

Inhaling gas 259

Instruments for application... 266

Insurance companies 281

Melon plant-lice 269

Method of application 270

Mice destroyed 283

Mills and other buildings 270

Mole cricket 268

Phylloxera 262

Prairie-dogs . . . 277

PAGE
Carbon bisulphid— Continued

Rats destroyed 283

Root-maggots 267

Root- worms 267

Squirrels. 277

Stimulating effects on plants. 274

Time to do work 271

Treatment of seeds 274

Vapor 259, 280

Weevils 282

White grubs 268

Woodchucks 282

Woolens 276

Wyoming 278

Carnations 135

Cars 166

Certificates 232, 235

Chemicals 9

Comparative value of cyanide. 83

Cost of 66

Estimating amount. 76, 77, 118, 162
Estimating for California

orchards 78

Estimating for Eastern or-
chards 83

Needed on damp ground 81

Cold frames 144

Coleus 134

Connecticut 236

Conservatories 200

Cottony cushion scale 1

Criminals 221

Cucumbers 24, 150

Culver fumigator 27, 81

Cuttings 199

Daylight fumigation 84

Deadly nature 25

Deposits forming 11

Diffusion 114, 186, 189, 193

Dry gas process 4

Dwelling-house 166

Economic use 1

Effects on animal life 25

Elevators 153, 170

Emory fumigator 8, 28, 59

England 198

Explosive properties 167

Ferns 133

Florida 236

Foliage 3, 127, 192

311

3I2

FUMIGATION METHODS

•AGE

Fresh earth 192

Fumigation, Cost of 89, 119, 247

Equipment 93

Figures 209

Materials needed 121

Value of 221

vs. Spraying 226

FuHiigatoriurn 97, 98, 99, 104

109, 110

Fu mi gator, box type 72

Box used in Canada 95

Box used in South 94

Cost 66. 71, 75

Lowe type 74

Miller type 67

Sirrine type 216

Generating 4,9,115, 160, 164

Generator, position 113

Good points 154

Grain 153, 177

Grapes 127, 136

Greenhouses. ... 15, 126, 136, 140, 145
202, 203, 224

Help required 66

Hoop tent 41, 89

Houses 174

Idaho 238

Insects in mills 158, 161

Jars, Preparing 130

June buds 22

Laboratory 174

Ladybirds— Introduction 5

Laws 285

Alsace-Lorraine 307

Austria-Hungary 303

Baden 307

Bavaria 307

Bremen 307

British Columbia 304

California 287

Canada 230, 304

Cape of Good Hope 305

Colorado 287

Connecticut 287

Delaware 288

Florida 288

France 306

Georgia 289

Germany 306

Hamburg 307

Idaho 289

Illinois 290

Indiana 290

Iowa 290

Kentucky 290

Kingdom of Saxony 307

Louisiana 291

PAGE
Laws — Continued.

Liibeck 307

Maryland 291

Massachusetts 292

Michigan 292

Missouri \ 293

Montana 293

Netherlands 308

New Jersey 295

New York 295

New Zealand 308

North Carolina 296

Ohio 297

Oldenberg 307

Oregon 298

Pennsylvania 299

Prussia . .., 306

South Carolina 299

Switzerland 308

Tennessee. . .t 300

Turkey 309

Utah 301

Virginia 301

West Virginia 302

Wisconsin 302

Wurttemberg 307

Leaf buds 11

Leaf -rollers 24

Lemons 254

Lettuce 24

Lifter 52

Louisiana... .. 239

Mandarin 254

Massachusetts 239

Mealy bugs 203

Mechanical mixer 191

Melons 150

Michigan 239

Mills 8, 155,159, 170

Mississippi 240

Missouri 240

Morse f umigator 28, 32

Nebraska 241

New Jersey 242

New South Wales 203, 252

New York 212, 242

Night fumigation 6

North Carolina 241

North Dakota 242

Nursery stock 42, 16, 223, 232

Nurserymen, Points for 123

Objectors 246

Ohio 243

Olive trees 225

Ontario 233

Oranges 253

Orchard trees 7, 65, 218, 234

INDEX

313

Paint 31

Palm scale 229

Peach trees 20

Pennsylvania 243

Plants 135, 150

Plum trees 15, 19

Preble f umigator 36

Purple scale 80

Red scale 5, 80, 227

Residue 11, 166

Rhode Island 244

Root aphis 24

22, 135

San Jos6 scale 7

Scale insects, Aspidiotus auran-

tii 5

Aspidiotus ficus 224

Aspidiotus perniciosus 7

Icerya purchasi 2

Seeds 24, 177, 180, 181

Sheet tent, Construction 48

Covering orange tree 51

Management 48

Removing with horse 55

Ships 166

Small plants 132

Soda process 3

Strawberry plants 24, 147

Sulphur fumes 153

PAGE

Tents, Adjusting hoop 41

Canvas 27, 32

Care 91

Construction 28

Cost 30, 206

Covering tree 44

Manipulating 48

Materials 28, 206

Oiling and painting 31

Raising 35

Removing 39

Sheet 31

Size 28

Testimonials 168

Titus f umigator 27

Tobacco fumes 153

Warehouses 169

Tomatoes 136

Trees 4, 120

Utah...

251

Value 1

Vegetable houses 139

Ventilators 112

Vessels 10

Vineries 200

Violets 127,134,146

Virginia 245

Wagon 91

Winter treatment 213

Wolf skill f umigator 27

Works at:

Perth Amboy
New Jersey

Cyanide of Potassium

Guaranteed ?8/99 per cent.

FOR GENERATING

Hydrocyanic Acid Gas

THE MOST EFFECTIVE

FUMIGATING MATERIAL

To Destroy Scale Insects on Fruit Trees, Nur-
sery Stock, and Plants of all kinds under
Glass and in Greenhouses; also Insects in
Mills, Elevators, Warehouses, Cars, Ships, etc.

... Manufactured by the ...

Roessler 6 H&>ssl&.cher Chemical Co.

100 William Street, New York

FUM A

CARBON BISULPHID

Creates a death atmosphere in which
no animal life can exist

"The wheels of the gods grind slow but exceeding
small." So do weevil, but don't let them grind your grain.
Kill them with "FUMA," as others are doing.

I reach the consumer direct, and FUMA reaches all insect
pests in stored grains and seeds, and gophers, prairie-dogs,
woodchucks and ants in the field.

" A simple, effective, and comparatively cheap remedy for insect pests
in stored grain is FUMA CARBON BISUIyPHID."— Prof. W. G.JOHNSON.

Orders for FUMA come from practical men every day.

EDWARD R. TAYLOR, Penn Yan, N. Y. — Dear Sir: Four years ago
we were bothered with weevil. We bought five gallons of FUMA and it
did the work. Ship at once (Sept. 3, 1901) five gallons more of the same
stuff. Yours very truly, HENRY W. HUNT, Palmyra, Wis.

WELLAND, ONT., Sept. 19, 1901. — Dear Sir: The last FUMA sent us
has done the business. Occasionally we find bugs on bags, etc., but they
are dead. In bins we used cotton-waste balls well saturated with FUMA
instead of plates, as before. We also poured FUMA around spouts and on
wheat, which in our opinion is the safest way of exterminating the pests.
—BROWN BROS.

A bit of cotton, rags, dry horse-manure balls, or even
grass, saturated with about two tablespoonfuls of FUMA, and
thrust into the burrow of a gopher or squirrel, will kill them
every time.

Do not ask dealers to make you prices, but write to me.

Price of FUMA, f. o. b. cars at Penn Yan, N. Y., in 50-pound
steel drums, 10 cents per pound. Cash must accompany the
order.

For minute directions for using and applying FUMA see
CHAPTER XXI. in this book ; but write to

EDWARD R. TAYLOR,

Manufacturing' Chemist,

Penn Yan, N. Y.,

,..AND GET THE ONLY GENUINE...

FUMA

STANDARD BOOKS

..PUBLISHED BY..

ORANGE JUDD COMPANY

NEW YORK CHICAGO

52 & 54. Lafayette Place Marquette Building

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Play and Profit in My Garden.

By E. P. ROE. The author takes us to his garden on the rocky hill-
sides in the vicinity of West Point, and shows us how out of it, after
four years' experience, he evoked a profit of $1,000, and this while
carrying on pastoral and literary labor. It is very rarely that so
much literary taste and skill are mated to so much agricultural ex-
perience and good sense. Cloth, i2mo. $ i.oo.

Grape Culturist.

By ANDREW S. FULLER. This is one of the very best of works on
the culture of the hardy grapes, with full directions for all depart-
ments of propagation, culture, etc., with 150 excellent engravings,
illustrating planting, training, grafting, etc. Cloth, i2mo. $1.50.

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