224 STATE HORTICULTURAL. SOCIETY. 



likely a combination of two or more, may furnish the requisite conditions 

 for its development. 



The use of scabby potatoes as seed was at one time said to lead to the 

 development of scab in the resulting crop, but from various experiments 

 this is not considered probable. 



It has been claimed that the use of sulphur would cause a great decrease 

 in the amount of scab, but our experiments have not shown this to be the 

 case. 



In order to have an opportunity to study the development of the scab 

 and to test the effect of various substances upon it, a scab plot was laid out. 

 It contained twenty-four rows, one and a half rods long. The soil was 

 very even, of a loose, open nature, consisting of sand with a slight admixt- 

 ure of well-decomposed muck. 



It was furrowed out five inches deep and planted on the sixth of June. 

 Twelve rows were planted with West's No. 1, a variety with a thin, smooth, 

 pinkish white skin, and the other twelve with Timpe's No. 1, which has a 

 thick red skin. 



Before planting, rows 1 and 2 of each variety were treated with 12 

 ounces of hyposulphite of soda; 3 and 4 with 12 ounces of sulphate of iron; 

 5 and 6 with 7^ ounces of sulphur; 7 and 8 with 2 pounds of sulphate of 

 potash, 9 and 10 with 2 pounds of sulphate of potash, and 4 pounds of 

 ground bone; 11 and 12 were not treated. 



Two hills of each of the odd rows were dug at intervals of a week after the 

 tubers set, and the even rows were dug after the vines were dead. 



The first scab was found on the 2oth of July upon West's No. 1. The 

 largest tubers were at that time one inch in diameter and these were the 

 only ones affected. The lenticels were brown and a thin deposit of cork 

 had commenced. The rows treated with soda hyposulphite were most 

 affected. 



The tubers of Timpe's No. 1 were fully as large but no scab was found 

 upon them. 



On August 1, two more hills in each row were dug, and it was noticed 

 that although there was a considerable increase of scab on West's No. 1, it 

 had not made its appearance upon Timpe's No. 1. From this date there 

 was a gradual increase in the size and number of scab spots upon the light 

 colored tubers. The worst cases were where soda hyposulphite was used, 

 there being no appreciable difference in the other rows. The scab was 

 only occasionally noticeable on Timpe's No. 1, except where the soda hypo- 

 sulphite was used. 



The remaining rows were dug upon the 8th of October; they were 

 weighed, counted, and assorted into three lots, free from scab, slightly 

 scabby, and those badly affected. 



Owing to an error in digging West's No. 1, treated with soda hyposiil- 

 phite, the results are not given, but the scab was more abundant than in 

 the other cases. 



With the other chemicals there seems to be a slight improvement where 

 the sulphur was used, but this may have been accidental. Timpe's No. 1 

 was entirely free from scab where untreated, and in the rows where sulphate 

 of iron and sulphate of potash and ground bone were applied. ^ The rows 

 on which sulphur and sulphate of potash were used had about 5 per cent, 

 of slightly scabby tubers, while hyposulphite of soda caused an apparent 

 increase of 23 per cent, in the amount of scab. This seems to be in accord- 

 ance with the theory that it is caused by the action of irritating chemicals 



