1887.] PUBLIC DOCUMENT — No. 33. 91 



Plat No. 4. A saturated solution of carbolic acicl in water 

 served in this instance for the treatment of the seed potatoes. 



Plat No. 5. The seed potatoes used in this plat were treated, 

 previous to planting, with a strong abstract b}' cold water ot 

 "The Potato Protector" of John Butterworth & Co., Mansfield, 

 Mass. This material was sent to the Station, for an opinion 

 regarding its merits, at a time when active preparations were 

 under way to test by field experiments whether substances like 

 those above stated would prove efficient to prevent the propaga- 

 tion of "scab" by seed potatoes. The practice of treating 

 wheat and other seeds for similar purposes with solutions of 

 sulphate of copper, etc., is not uncommon in other localities. 

 As the " Potato Protector" proved to contain quite a noticeable 

 quantity of a powerful agent, hypochlorite of lime, it was 

 thought best to introduce the material into our experiment, 

 instead of offering a mere opinion regarding its merits. The 

 results of an examination into the composition of the " Potato 

 Protector" are published with some comments at the close of 

 this chapter. 



The potatoes were planted in all plats on the same day, 

 May 7, 1886 ; the young vines appeared on Plats 1 and 5, 

 May 25, whilst on Plats 2, 3 and 4 they did not show themselves 

 before the 29th of May, and not as generally and evenly as on 

 Plats 1 and 5. This difference in growth could be noticed until 

 towards the close of June, when the vines on all plats looked 

 equally vigorous and thrifty. The vines on all the plats were, 

 at this stage, vigorously attacked by the potato bug, and were 

 protected against their destructive influence by a repeated 

 sprinkling with a solution of Paris green. They began to bloom 

 July 6. The vines on Plat 1 began first to turn yellow and to 

 dry up July 30 ; those on the remaining plats began to change 

 in a similar way August 8. The tops on all the vines were 

 pretty generally dried up August 18. The potatoes were har- 

 vested on the entire field August 30. The yield on all plats was 

 fair and the quality of the potatoes, almost without excep- 

 tion, excellent; this seemed to be most striking in regard to 

 those from Plats 2, 3 and 4, which had been in the beginning 

 of the season somewhat behind in OTowth. Here and there 

 could be seen a potato with a small mark of scab ; a large pro- 

 portion were perfectly smooth and without any sign of it. 



