1913. 



PUBLIC DOCUMENT — No. 31. 



89 



Where solid substances were used, the substance was mixed 

 thoroughly witli the top 4 inches of soih 



In the following table a check tile was used alternately with 

 a treated tile, and as the amount of scab on the potatoes in all 

 the check tiles was practically the same, the checks are 

 omitted : — 



Tahle I. — Plan of Potato Scab Experiments, IOCS. 



Pot 

 Num- 

 ber. 



SUBSTANCK USED. 



Amount used. 



Formalin, 1-100, 



Formalin, 1-200, 



Formalin, 1-300, 



Formalin, 1-400, 



Potassium permanganate, 1-100, 



Potassium permanganate, 1-300, 



Potassium permanganate, 1-400, 



Potassium permanganate, 1-500, 



Sulfuric acid, 1-200, 



Sulfuric acid, 1-400, 



Sulfuric acid, 1-600, 



Sulfuric acid, 1-800, 



Acid phosphate, 



Acid phosphate. 



Acid phosphate. 



114 cubic centimeters. 



57 cubic centimeters. 



38 cubic centimeters. 



28.5 cubic centimeters. 



57 grams. 



38 grams. 



28.5 grams. 



23 grams. 



57 cubic centimeters. 



28.5 cubic centimeters. 



19 cubic centimeters. 



14.25 cubic centimeters. 



57 grams. 



38 grams. 



28.5 grams. 



The potatoes were cultivated in the usual way and allowed to 

 mature. When dug the yield was taken of each pot separately, 

 and the relative amount of scab as compared with the corre- 

 sponding check tile, but in most cases the yield and amount of 

 scab present closely approximated the check, so nothing of value 

 was obtained from this experiment, as a whole. It was noted, 

 however, that the tiles treated with formaldehyde or formalin 

 were somewhat freer from scab individually ; also in the case of 

 the permanganate very little yield was obtained, but the usual 

 amount of scab was present. The sulfuric acid treatment 

 showed possible beneficial effects, but the yield was so small 

 that no accurate comparison could be made. 



