Vol. LIX. No. 2608. 
NEW YORK, JANUARY 20, 1900. 
$1 PER YEAR, a 
THE USE OF HYDROCYANIC ACID GAS. 
FOB KILLING INSECT PESTS AND VERMIN. 
Its Use Outdoors and in Buildings. 
Part II. 
IN THE ORCHARD.—Since 1899 hydrocyanic acid 
gas has been extensively used in the Citrus orchards 
of southern California for the destruction of the 
Black scale and the Red scale, which militate so 
much against the successful growing of oranges. 
Sprays could not be used, as substances that would 
destroy the insects injured the fruit to such an ex¬ 
tent as to make it unsalable. The area in which this 
gas is most extensively used is covered by the seven 
southern counties of California. Here the large 
orange orchards are fumigated regularly and system¬ 
atically, by men who make a business of fumigating. 
The work is done at night, to avoid the burning effect 
the gas has upon the foliage when applied in the di¬ 
rect sunlight. The gas is also used to some extent in 
Florida, and, no doubt, in the near future will be 
more commonly used there. Recently, I had a letter 
from a large orange grower in Florida, who stated 
that he would have to do something to destroy the 
Red scale in his orchard, or “it would clean him up.^’ 
During the past two years the gas has been used quite 
extensively in Cape Colony South Africa. In 1897 
there was one outfit at work, fumigating a few Citrus 
orchards; but in 1898 nine outfits, owned and man¬ 
aged by local organizations, were in the orchards, 
and about 27,000 trees were fumigated. The results 
have been very satisfactory, and other associations 
are being organized. I might say, also, that the nur¬ 
serymen of the Cape are awake to their interests, and 
have constructed fumigating houses, many of them 
brick, for use in their business. 
USED IN MARYLAND.—Although extensively used 
in California since 1889, the gas was scarcely known 
in the East to the growers of deciduous fruits, until 
the invasion of the San Jos6 scale. The discovery of 
this pest in the eastern United States in August, 1893, 
brought forth a circular bulletin from the United 
States Department of Agriculture, that thoroughly 
aroused public interest, and a score or more of eco¬ 
nomic workers were in the field shortly afterward. 
The outcome of these inspections and researches is 
well known. The first application of the gas for the 
destruction of scale on deciduous trees, in the or¬ 
chards of the East, so far as I am aware, was made 
by Mr. D. W. Coquillett, for the United States De¬ 
partment of Agriculture, in the Virginia orchard, in 
March (1894), succeeding its discovery. Very little 
was done, in the way of perfecting the system and 
determining the physiological effects of the gas upon 
deciduous trees for the next two years. In the Fall of 
1897 we ucgan the largest series of experiments un¬ 
dertaken in the East with gas, to clear up the doubt¬ 
ful points and determine, by actual test, the practic¬ 
ability of this method in large bearing orchards. The 
FUMIGATING DWARF PEAR TREES. Fig. 10. 
orchard selected was of nine-year-old dwarf Bartlett 
pears. Canvas tents, similar to those used in Cali¬ 
fornia, were constructed. The trecc were covered, as 
shown in the illustration, Fig. 10. The fumigation 
was conducted at all hours of the day and at night, 
with varying doses of gas. The weather conditions 
were also variable. We had sunshine, cloudy and 
foggy days, rain, sleet and snow windy and calm 
weather. The experiments were continued in March, 
1898, and in April, 1899. 
EFFECT Or' THE GAS.—While we demonstrated 
to our satisfaction that the gas could be used in our 
large bearing orchards, we were not satisfied with 
the tent system. The cubic contents of a tented tree 
is not constant, as one can imagine at a glance at the 
illustration, and the weight of the tent broke many 
twigs and fruit spurs. We s X out to overcome these 
objections in the Fall of 1898, and constructed a 
large box six feet square and eigni feet high, as 
shown in Fig. 12. It was covered with heavy raw- 
hide paper, and had a seven-foot extension top, or 
hood, made of eight-ounce duck. The box was hinged, 
and when transferred from tree to tree, the butts were 
removed from one side, the hood loosened at the top, 
and the box opened easily as shown in Fig. 11. We 
found that this worked very well, and gave us a cubic 
capacity that did not fluctuate to any great extent; 
THE FUMIGATING BOX OPENED. Fig. 11. 
but too much time was consumed in placing the hood 
Jlnd hinging the box each time. 
A PERFECT BOX.—The next step, therefore, was 
the perfection of a canvas box, with hood and sides 
securely fastened with screws. This required a 
special rigging for manipulation, which was con¬ 
structed and used as shown in the illustration, Fig. 13. 
In April, 1899, we used this system in a large bearing 
orchard. We were able to handle the boxes with 
ease, and cover trees varying from 10 to 18 feet in 
height. As the contents of these boxes are con¬ 
stant, the only variation is in the extension of the 
hood, which is easily calculated. This system can 
be handled by almost any orchardist, while the tents 
could be handled only by an expert, and then with 
varying results. The effectiveness of the gas system 
depends upon preciseness and thoroughness of appli¬ 
cation. The liability of error is thus minimized in 
the new system. In all my practical experimental 
work I have had the assistance of Mr. Robert S. 
Emory, one of Maryland’s largest, and most success¬ 
ful fruit growers. Without his timely suggestions 
and help, the new system would not have been com¬ 
pleted. It is a great pleasure for me, therefore, to 
call this new system the Emory fumigator, as a 
Slight recognition of his services. 
A BOX FOR FUMIGATING TREES. Fio. 12. 
OUTDOOR FUMIGATION.—As indicated above, we 
have conducted our experiments in September, Octo¬ 
ber, November, March, and in April. In our first 
work in 1897, the leaves were still on the trees; but 
their function had been performed, and the browning 
of the foliage had no injurious effect, as subsequent 
observation indicated. Considering everything, I pre¬ 
fer to fumigate late in March or early in April. The 
weather with us is usually more settled than late in 
the Fall. Large blocks of trees can be fumigated. 
In one instance, we fumigated over 2,000. Whether 
an individual grower can afford an outfit of his own, 
of course, depends largely upon circumstances. I do 
not believe, however, that many outfits will be owned 
by private parties. If conditions warrant it, an out¬ 
fit could be owned and operated by a local organiza¬ 
tion, as done in California and South Africa. Some¬ 
times private interests are such, one would be justi¬ 
fied in havin 0 one or more Emory fumigators. In 
fact, such an outfit has been recently sent by us to 
South Carolina. 
In all of our outdoor work in orchards we use .20 
(20 hundredths) gramme cyanide per cubic foot of 
space enclosed. We never leave a tree exposed to the 
gas for less than a half hour, and longer, say 45 to 
60 minutes, is preferable where time and conditions 
will permit it. It requires three or four men to op¬ 
erate an outfit of eight to 10 Emory fumigators. One 
man looks after the chemicals, while the others at¬ 
tend to the rigging and tents. From 175 to 200 trees, 
from 12 to 17 feet in height, could be fumigated in 
one day with this force. The cost of the chemicals 
for the fumigator (6x6x8) is about four cents, with¬ 
out hood extended; five to six cents with hood half 
extended; and six to seven cents with hood fully ex¬ 
tended. The cost of tne fumigator complete is about 
the same as for a sheet tent that would cover the 
same sized tree. The large fumigator costs from $20 
to $30 complete. The rigging for handling the ap¬ 
paratus costs about $10 to $12, and can be attached 
to the running gears of an ordinary cart. 
Maryland Exp. Station. [prof.] w. g. johnson. 
KEEPING APPLES.—I noted that two of your cor¬ 
respondents, In their advice as to the best way for 
keeping apples, advised that the cellar should be a 
dry one. Here in eastern Massachusetts we don’t 
think that way, but would prefer a damp, cool cellar, 
especially with the russet varieties, which are inclined 
to shrivel in a dry cellar. About 50 years ago, when a 
young college graduate, I was teaching a country 
academy in Massachusetts. At apple-picking time, 
one of my schoolboys brought me a Roxbury Russet 
from his father’s cellar, in sound condition, that had 
been picked the previous year. The next day he 
brought me another that had been picked two years 
before. This also was sound, but it looked and tasted 
much as a cellar smells. I investigated, and learned 
that the apples had been kept in the house cellar, in 
barrels with bags thrown in on them, and that the 
cellar differed from ordinary cellars in being quite 
damp, which would be inferred from the fact that a 
stream of water flowed parallel with one end of the 
house and within six feet of it. j. j. h. Gregory. 
Marblehead, Mass. 
