April, ’23] 
DISCUSSION OF UNIFORM FUMIGATION REQUIREMENTS 
165 
mend the same size dosage to nurserymen for the same kind of nursery 
stock. 
One reason why this should be done is to insure all nursery stock 
shipped being fumigated with a sufficient dosage of gas to kill all the 
pests. Another reason is that the nurserymen would better comply 
with the fumigation requirements of the states in a certain group if 
the fumigation regulations in all were similar. 
Some of the state plant inspection officials are of the opinion that 
dipping nursery stock in a miscible oil or oil emulsion is as effective as 
fumigation with hydrocyanic acid gas and even more satisfactory. 
This may be true, providing the dipping is carefully done. Dipping 
could probably be substituted for fumigation by the small nurserymen 
better than by the large nurserymen, since it is cheaper to fumigate a 
large quantity of trees than it is to dip them in a miscible oil or oil 
emulsion. 
After having collected data from the several states on fumigation 
formulas in use, time required for fumigation and other information, and 
find that there is so much variation, one naturally hesitates to make 
any recommendations along the line of standard fumigation requirements 
for even a group of states. It would seem highly desirable that a num¬ 
ber of experiments be conducted in several sections of the United States 
to determine what fumigation requirements might be considered stand¬ 
ard in each group of states in the country. 
Mr. E. R. Sasscer: I regret very much that we do not have more 
time to discuss this important problem. It is one which deserves more 
attention than it is receiving on the part of those requiring the fumiga¬ 
tion of nursery stock as a condition of distribution. Mr. Arnold was 
good enough to permit me to examine the replies he received to a ques¬ 
tionnaire, and I was astonished to discover that there are about as many 
formulae in vogue for the fumigation of nursery stock as we had in the 
old days for the preparation of lime sulphur and salt. It appears that 
many entomologists are unaware of the fact that at the request 
of Doctor Marlatt the United States Bureau of Chemistry worked out 
a formula which will give the maximum yield of gas from a given amount 
of cyanide. Information on this subject is given in Bulletin No. 90, 
Bureau of Entomology, published in 1912. In view of the thorough 
investigations made by the Bureau of Entomology in California and 
elsewhere there seems to be little excuse for the development of so many 
formulae. 
