1913.] PUBLIC DOCUMENT — No. 31. 95 



The yield of tubers was good in all cases. 



The formalin treatment gave varying results, and when used 

 in quantities sufficient to do good would be probably imprac- 

 tical. The results with formalin were as follows : — 



Formalin 1-100, 30 per cent. scab. 



Formalin 1-200, 40 per cent. scab. 



Formalin 1-300, 70 per cent. scab. 



Formalin 1-400, 70 per cent. scab. 



Clieck, 75 per cent. scab. 



The yield was only fair in these tiles. 



The carbon bisulfid treatment gave negative results, as may 

 be seen from the following: — 



Carbon bisulfid, 15 cubic centimeters, fair yield, 80 per cent. scab. 

 Carbon bisulfid, 25 cubic centimeters, poor yield, 3 per cent. scab. 

 Carbon bisulfid, 40 cubic centimeters, no yield. 



The ]^icine treatment gave no results that could be inter- 

 preted as either beneiicial or otherwise. 



The experiments for 1913 will be planned from an economic 

 point of view, and if possible the same experiments will be 

 carried out for a series of years, and plots used in addition to 

 the tiles. 



In summarizing the results of experiments with potato scab 

 it will be noticed that many of the substances used had little 

 effect in preventing scab, while others seemed to possess some 

 value. Steaming the soil the second year was done somewhat 

 more thoroughly than the first year, but the results, on the 

 whole, were similar, i.e., in all the sterilized plots, 1911-12, 

 there w^as little evidence of reduction of the scab. Steaming 

 under pressure or for prolonged periods under no pressure 

 would determine once for all whether the scab germs are un- 

 usually resistant to heat. The heated soil, however, proved to 

 be beneficial to the crop, as the yield was good under this 

 treatment. 



The best yield in 1912 was given by by-product A in dry 

 form, followed by the sulfur treatment, and the by-product A 

 wet treatment and steam heating. The most satisfactory treat- 

 ment from the yield point of view as well as that of treatment 



