.New York .Agricultural Experiment Station. 775 



decided practical advantages over the treatment with liquid, because 

 of its greater convenience and its lessening of the task of handling 

 the potatoes. It soon promised to supersede these older methods. 



In the spring of 1912 the Station Botanist and his 

 Gas injures associate had occasion to disinfect nearly 90 bushels 

 tubers in of potatoes stored in bushel crates in a large cellar 



Station work, under the Station tool-house. As no smaller room 



was convenient and as the labor of moving the 

 crates would have been considerable, it was decided to use the entire 

 cellar as a disinfection room. This involved much larger amounts 

 of chemicals than needed, since the entire space must be filled with 

 the gas although the tubers occupied only a small part of it. 



In the fumigation the method used was that recommended by Prof. 

 Morse of Maine, one of the adapters of the use of permanganate and 

 formalin for potato treatment. To the great surprise of the investi- 

 gators, they found that many of the tubers were seriously injured by 

 the treatment, particularly those most exposed in the top crates. In 

 many cases the eyes of the potatoes were surrounded by circular, 

 sunken areas of brown, dead tissue, while on these tubers and on 

 many others, the skin was marked, as shown on the title page illustra- 

 tion, with numerous sunken brown spots, of various shapes and 

 ranging in size from mere specks to areas a half-inch across. Many 

 of these spots were circular ones, each surrounding a lenticel, or 

 minute pore-like opening through the skin of the tuber. The potatoes 

 in the forty crates on top were sorted, and one-fourth of them rejected 

 as too seriously injured to be used for seed. 



This unfortunate result, so contrary to experience 

 Search for elsewhere, made advisable a very careful study of the 



cause of conditions to ascertain the reason for the damage, 



injury. During the remainder of the spring of 1912 and in 



the winter and spring of 1913 more than 80 lots of 

 potatoes were fumigated, varying the conditions in many directions 

 in order to cover any change in the factors that might possibly have 

 been concerned in the trouble. 



Variations in the temperature of the air in the disin- 

 Effect of fection chamber were shown to have very slight 



temperature effect on the amount of injury, even when the 

 changes. range was as great as 45° F. At temperatures below 



50° the gas showed a slight tendency to change to 

 paraformaldehyde, in which condition it becomes a whitish, powdery 

 precipitate and is probably useless for disinfection. In some of the 

 tests at low temperatures this " paraform " appeared as a very faint 

 deposit of whitish dust on sheets of black paper in the disinfection 

 chamber; but the reduction of the action of the gas was very slight; 

 since the injury to tubers at 42° where this change was noticed was 

 no less than at 87° where no such change would take place. 



