POTATO DISEASES- HST I907. 305 



possible, and as a farther precaution it was stated that the seed 

 should be treated with a disinfectant to destroy any germs of 

 the scab fungus which might be present. For small lots soak- 

 ing in formalin or corrosive sublimate solutions is the usual 

 method, but for the large grower or seed dealer formaldehyde 

 gas, generated by the use of potassium permanganate, was 

 recommended. This is a much more convenient and rapid 

 method of treating the seed, but up to the present season it 

 had not been tried on a commercial scale. 



Through the courtesy of Mr. John Watson of Houlton a 

 20-acre field in that town was placed at the disposal of the 

 Station to test the matter on a large scale. About one-half of 

 this land had never been planted to potatoes before, while the 

 remainder had been in cultivation for many years. A house 

 formerly stood on this part of the field and presumably some 

 of the land near the house was devoted to garden purposes. 

 One portion of the old land also had been used in an alfalfa 

 experiment in 1904. Of the part planted to alfalfa one-third 

 was limed, one-third treated with a heavy application of wood 

 ashes, while commercial fertilizer alone was used on the remain- 

 der. Hence, it was not expected that scab could be cut down 

 materially on the old ground, but it was hoped that its intro- 

 duction into the new soil could largely be prevented. 



For a disinfecting chamber a room was partitioned off in the 

 basement of the barn. This chamber was 15 feet 3 inches by 

 11 feet 8 inches and 7 feet 7 inches high and was large enough 

 to treat 75 barrels of seed at one time. There was already a 

 plank floor and the side of the barn formed the back wall of 

 the chamber. The floor was first covered with builders' paper 

 and then with rough boards. To build the walls the studding 

 was set and first covered with paper and then unplaned boards 

 nailed over this on the inside. The top was first boarded over 

 and then this and the back wall were covered with paper held 

 down by strips of lath nailed over the joints. Care was taken 

 to cover with paper all joints at the corners and at the junction 

 of the side walls and floor. The door was carefully fitted and 

 shut into a joint covered with paper. When the door was 

 closed 3 wooden cleats or bars were placed across it passing 

 under other slightly slanting cleats nailed to the studding, thus 

 drawing the door tight against the casing. 



