270 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908. 



TESTS OF VARIOUS GASES FOR FUMIGATING 



NURSERY TREES' TO DESTROY SAN 



JOSE SCALE.* 



The object of the tests herein described was to ascertain if 

 there is any gas that can be used more conveniently than hydro- 

 cyanic acid gas, especially in fumigating small lots of trees, 

 cions ahd budsticks. For this, purpose the materials must be 

 reasonably inexpensive, the gases easy to generate, the apparatus 

 simple, and the operation comparatively free from danger to the 

 operator as well as harmless to the trees. 



The writer was assisted in the chemical part of this work by 

 Mr. F. H. Heath, a graduate student in chemistry in Yale Uni- 

 versity; and by Mr. B. H. Walden, who did most of the fumi- 

 gating work. 



Some orchardists and nurserymen are considerably prejudiced 

 against fumigating trees with hydrocyanic acid gas. This 

 prejudice is not well-founded though it must be admitted that 

 many trees have been injured by leaving them too long in the 

 fumigating house, and by attempting to fumigate them when 

 wet. When ptoperly done according to the methods usually 

 recommended, no injury results. This has bpen proven over and 

 over again, not only in our own experiments, but also in the 

 tests made by other entomologists. 



In a large fruit nursery where most of the stock is dug in the 

 fall and not sent out until the foHowing spring, it is an easy 

 matter to fumigate the stock before heeling it in on the grounds. 

 But it often happens that a customer calls for two or three trees 

 which have not been dug or fumigated. The nurser3mian dis- 

 likes to turn away a customer, and if possible will furnish the 

 stock desired. Of course each well-equipped nursery should 

 have small fumigating boxes in which a few trees or shrubs can 

 be treated, in addition to the large fumigating house. But most 

 of them have only the large house, and it is very expensive to 

 charge it with gas for only a few trees. Some of the small 



* A brief abstract of this paper was given at the meeting of Economic 

 Entomologists at Chicago, December 27-28, 1907, and will be published 

 in the Journal of Economic Entomology. 



