EXPERIMENTS WITH HEFKREXCE TO THE PuTATO DISEASE. 61 



Sulphuric acid 1 part to 200 parts of water. — Table Y. 6. 

 Quantity to a row \ pint, in 25 pints of water. Estimated quan- 

 tity per acre, 13^ gallons of sulphuric acid, and 2650 gallons of 

 water. Diluted to this extent, the acid had the efiect of slightly 

 browning the foliage and partially checking the excessive vege- 

 tation of the tops, M'hich were previously elongating at an over- 

 rapid rate. In consequence of the slower development occa- 

 sioned by this check, leaves of thicker sulDstance and of a darker 

 green were produced. When the growing extremity of a shoot 

 is pinched or checked, the leaves below usually increase in size 

 and in thickness of substance. Such was the case in this expe- 

 riment with regard to the leaves existing previously to the 

 application ; and those subsequently formed were not so soft nor 

 so pale green as leaves of the same age in the adjoining rows, to 

 which nothing was applied. Excessive elongation of the stems 

 and paleness of the foliage being amongst the characteristics of 

 the disease, the effects of the application tending to the reverse 

 of these conditions were favourably anticipated. On referring 

 to the table, it however appears, that altliougli the amount of 

 sound produce, estimated per acre, was upwards of 9 tons 9 cwt., 

 yet the proportion diseased exceeded 12 per cent. In short, the 

 amount of sound produce was less, and the diseased portion more, 

 than in the adjoining row which had nothing. 



Solutions oi sulphate of magnesia were applied, June 18th, to 

 3 rows of early Manly potatoes growing in the same plot of 

 ground as those were to which the sulphuric acirl was given. 

 The rows were 22 feet in length ; cut tubers were employed for 

 sets, planted at the same distances as in the preceding experi- 

 ments. The quantities ajjplied to the respective rows were, 



2 oz., 1 oz., 2 oz. Sulphate of magnesia, in 25 pints of water. 



Estimated per acre, the above quantities correspond with 

 106 lbs., 53 lbs., and 26:^ lbs. To three other rows the same 

 quantities of chloride of lime were similarly applied. For the 

 results, see Table Y. 8 and 13 inclusive. The above solutions 

 did not injure the foliage when applied. They produced no 

 marked effect on the plants. In the row to which 1 oz. of sul- 

 phate of magnesia was applied, there were no diseased tubers ; 

 and in the row which had 1 oz. of chloride of lime, less than 

 1 per cent, was diseased. The Early Manly variety, however, 

 appeared to be less afliected than the others here experimented 

 with ; for the produce of the row which had nothing, Table V. 

 14, was diseased to the extent of not more than ^\ per cent. 

 A larger proportion than this was diseased in the row to which 



