THE NATIONAL NURSERYMAN. 
39 
FUMIGATING STOCK. 
Details of the Use of Hydrocyanic Gas in the Nursery—In Maryland 
Exact Amounts for Each Fumigating House Are Weighed 
at the Experiment Station —No Injury to Dormant 
Trees and Shrubs—Outdoor Fumigating. 
The managing editor of the Rural New Yorker has been at 
the nursery J. G. Harrison & Sons, Berlin, Md., to see how 
hydrocyanic gas is used in fighting the San Jose scale and he 
writes entertainingly of his visit. There were two large fumi¬ 
gating rooms, he says. They are large enough to hold a wagon 
loaded with trees. They are double-boarded, for it is neces¬ 
sary to have them absolutely air-tight. The doors are also 
double-boarded, and fastened with movable cleats, so that they 
can be tightly closed. One of the rooms contained 10,000 
peach trees. The process of fumigation was as follows: 
The room was tightly closed with the exception of one small 
door. They then brought a large earthen jar containing a quan¬ 
tity of water, and set it inside the door. From a jug containing 
sulphuric acid, a quantity was measured out into a glass flask, 
and poured into the water which, evidently, began to heat up. 
A package of a white substance wrapped in a yellow paper was 
then taken out of a box. The man with the package held it 
over the jar, opened the paper, took a long breath and dropped 
paper and all. He rushed out and shut the door. After half an 
hour the door was opened and the room was aired for fifteen 
minutes before any one was allowed to enter. 
State Entomologist Johnson explained that the amount of 
cyanide of potash used depends upon the size of the room 
Every fumigating house in the state has been accurately 
measured and the exact amount of cyanide of potash needed 
is weighed at the experiment station and sent in packages to 
the nurserymen. This is important because in generating the 
gas it is necessary to have it of just the right strength to kill 
all insects and at the same time to avoid injury to buds or 
roots. After many experiments the right proportion for safety 
and effectiveness has been ascertained. 
“ We decided to use one-fourth of a gramme of cyanide for 
each cubic foot of air space,” said Professor Johnson. “ For 
example, if we had a room containing 200 cubic feet of space, 
we use 50 grammes of cyanide at each charge. There are 
28.35 grammes in an ounce. This amount of pure cyanide is 
needed to fill that space with gas. We use 50 per cent, greater 
weight of acid than of cyanide, and 50 per cent, more of water 
than of acid. For example, if two ounces of cyanide are used, 
we use three ounces of acid and °f water. In this way we 
'regulate the amount of gas with scientific accuracy, and get far 
better and more uniform results than would be the case if the 
weighing and measuring were left to others. I superintended 
the building of every fumigating room in the state, ard we 
have exact measurements of all of them. 
“If this gas is properly generated and handled; it will de¬ 
stroy every scale upon the tree, whether there be 1 or 10,000. 
In 1897 we treated young trees of pear, peach, plum, cherry and 
apple. They were literally covered with the scale when we put 
them into the fumigating house. We set them where we could 
watch them every week. Not a living insect has been observed 
on those trees since. They were alive with the scale before 
we fumigated them, and they have now been growing for two 
seasons. We duplicated these tests in the spring of 1898, with 
the same results. We also took several badly infested trees, 
and placed them on the floor at the bottom of 5,000 nursery 
trees in one house. These were watched closely during 1898, 
and not a single insect developed. We are now absolutely 
certain that this terrible gas will kill every insect, if by chance 
they should be upon a tree. You may state positively that, 
when properly generated and applied, no breathing thing can 
can escape from this gas. 
You cannot possibly injure the roots of any kind of fruit 
trees with this gas. I he chemicals would have to be used 
about eight times the standard strength, to affect them in any 
way. At the strength we now use the gas, trees should never 
be left in the house for less than half an hour. You may safely 
leave them for hours, or even over night, without any injurious 
effect. Trees can also be fumigated two or even three times 
without being injured, although once is sufficient. The gas 
would injure the buds after they have started. The gas should 
be used on nursery stock only when the trees are dormant, either 
in the fall or spring. This can be accomplished readily, as 
nurserymen do not as a rule handle their trees after the buds 
begin to unfold. Most nursery stock is dug, fumigated and 
heeled in where it can be conveniently packed later. 
“ My outdoor fumigating is done mostly in the fall and win¬ 
ter. After the function of the foliage has been performed, and 
just before the leaves fall is a good time. In this case, the 
leaves are scorched on bright, sunshiny days, but the burning 
does no harm to the trees, as the leaves are nearly ready to fall 
anyway. We usually begin our outdour work about the mid¬ 
dle of September. We have also done some fumigating in 
March.” 
Jfoi’ctgn IRotes. 
There were exported from the United States and Canada to England, 
during 1898 - 99 , 1 , 100,000 barrels of apples; in 1897 - 98 , 715,100 
barrels. The largest consumers were London, Liverpool and Man¬ 
chester. 
The area in New South Wales suitable for the production of grapes 
for wines of all kinds is practically unlimited. Half a million phyl¬ 
loxera resistant varieties for use as stocks in the planting of new vine¬ 
yards have been sent to Australia from France. 
The schedule of the international horticultural exhibition at Mount 
St. Amand, Ghent, which opened on April 80 , comprises 868 classes. 
Prizes to the amount of 40,000 francs are offered, besides 98 gold and 
148 other medals, including medals from the king and queen. 
The new temperate house at Kew botanical gardens has just been 
completed. It is by far the largest plant structure in the world, says 
the Gardeners’ Chronicle. Its length is 582 feet, its greatest width 138 
feet, height of grand center 60 feet, height of wings 38 feet, ground 
area nearly two acres. The cost of the structure was $ 300 , 000 . 
A correspondent of the Gardeners’ Chronicle, London, writing from 
Erfurt, Germany, gives the following details regarding the wages paid 
to gardeners in that city : “At one of the largest and richest nurseries 
in this important town of Erfurt, the workmen (not improvers) receive 
10 to 15 marks weekly (a mark is about equal to 24 c.) Only the best 
workmen receive as much as 15 s. weekly (about $ 3 . 60 ), and a man 
twenty-five years of age, with a family, will only receive 11s. 8d. 
($ 2 . 80 ) weekly to commence, and his w T ages ■will increase at the rate of 
8d. ( 16 c.) weekly. Then the average weekly money earned by these 
poor fellows is 13 s. 6d. (about $3 25 ). Improvers are paid at the rate 
of 44 s. (about $ 10 . 70 ) monthly, rising yearly at the rate of 3 s. ( 72 c.) 
monthly.” 
