90 AGRICULTURAL EXPERIMENT STATION. [Jan. 



a possible propagation of scab, by infected seed potatoes, to 

 the new crop, the following course was adopted : Thoroughly 

 scabby potatoes obtained from the previously-described experi- 

 mental plats were treated with some substances known to be 

 destructive to various forms of parasitic growth. This opera- 

 tion was carried out with the intention of destroying the propa- 

 gating power of adherent germs of an objectionable character, 

 before planting the potatoes. 



The field for the observation was distinctly separate from 

 other experimental plats for the cultivation of potatoes. It had 

 been used for many years previous for the raising of grass, and 

 had since been planted but once, — the preceding year, — with 

 corn. The land was prepared l)y ploughing and harrowing, in 

 the same way as other potato fields : it was fertilized broadcast 

 with the same amount of fertilizer per acre as Plat No. 3, in 

 1884 and 1885, in the above-described experiment (A) ; 

 namely, six hundred pounds of ground bones and two hundred 

 and ninety pounds of potash-magnesia sulphate. 



The field was subdivided into five plats of equal size, 

 eighty feet long and fifty feet wide, and the potatoes subse- 

 quently planted in rows three feet three inches apart, with hills 

 three feet from each other in the rows. Three feet of space 

 was left unoccupied between the difierent plats. The scabby 

 seed potatoes selected for the trial were, as far as practicable, 

 of a uniform medium size. Each lot was immersed in the 

 particular solution prepared for the different plats ; after being 

 kept there for twenty-four hours they were removed, and 

 directly planted without any other operation. 



Plat No. 1 (north end of field). The seed potatoes used in 

 this case were smooth and healthy ; they were planted without 

 being subjected to any preparatory treatment. This course 

 was adopted to learn whether soil, fertilizer or atmospheric 

 agencies of the season would favor the appearance of the scab 

 in the crop. 



Plat No. 2. The potatoes were allowed to remain for twenty- 

 four hours in a saturated solution of muriate of potash before 

 being planted. 



Plat No. 3. A strong solution of hypochlorite of lime (bleach- 

 ing lime) was applied in a similar way for the preparation of 

 the seed potatoes as in Plat No. 2. 



