1913.1 



PUBLIC DOCUMENT — No. 31. 



91 



In the siill'iiric acid treatment no yields of potatoes were ob- 

 tained except in the check tile, and they averaged 60 per cent, 

 scab. 



In the snlfnr treatment the treated pots in general showed a 

 slight gain over the nntreated or check pots, bnt not enough to 

 warrant definite favorable conclusions being drawn. 



The plans for the experiments in the season of 1911 were 

 changed somewhat, and other, chemicals substituted for some 

 that were previously used. This was the result of the non-action 

 or the negative results obtained from some of the substances 

 used. The whole method of choice of substances was of course 

 haphazard, as no foundation for the use of some was warranted. 



In 1911 the chemicals used were as follows, and the only old 

 one to be used was formalin. Table III. gives the plan of the 

 year's experiments : — 



Table III. — Plaii of Potato Scab Experiments, 1911. 



Pot 

 Num- 

 ber. 



Substance used. 



Amount used. 



Steam-sterilizcd, . . . , 



Steam-sterilized, . . . . 



Steam-sterilized, . . . . 



Steam-sterilized, . . . . 



By-product A, . . . . 



By-product A, . . . . 



By-product \, . . . . 

 By-product .\, 



By-product A, . . . . 



By-product A, . . . . 

 K permanganate-formalin, 

 K permanganate-formalin, 

 K permanganate-formalin, 

 K permanganate-formalin. 

 Copper sulfate, 1-1,000, . 

 Copper sulfate (1 gallon), 1-10,000, 



Carbon bisulfid, . . . , 



Carbon bisulfid 



Carbon bisulfid, . . . , 



5 grams (dry). 

 10 grams (dry). 

 10 grams (wet). 

 15 grams (dry). 

 25 grams (dry). 

 40 grams (dry), 



100 cubic centimeters, 6 



grams. 

 25 cubic centimeters, 10 



grams. 

 40 cubic centimeters, 16 



grams. 

 60 cubic centimeters, 24 



grams. 



15 cubic centimeters. 

 25 cubic centimeters. 

 40 cubic centimeters. 



