182 



THE POTATO DISEASE. 



evidence adduced respecting remedies for this mysterious, and it 

 may be said hitherto unsubdued, disease in the potato, is so con- 

 flicting that none of the many applications propounded can be 

 relied on. The effects of different depths of planting have, how- 

 ever, proved such in the Society's garden as to deserve particular 

 attention. No depth, it must be premised, has been preventive 

 of the disease ; for under all circumstances the haulm gave way 

 before its natural period of decay. The condition of the tubers 

 was, however, remarkably affected according to the depth of the 

 sets, and subsequent earthing up of the stems. 



In the preceding experiments, as has been previously stated, 

 the sets were placed from six to eight inches deep. The average 

 sound produce was no less than fifteen tons per acre, the limed 

 portion yielding fifteen tons six hundred-weight ; diseased sets, 

 fifteen tons one hundred-weight ; and the others a few hundred- 

 weights less than fifteen tons per acre. 



In similar ground adjoining that in which the above large 

 produce was obtained, some potatoes were planted shallow, 

 having been previously prepared for an experiment by Mr. 

 Bickes, of Mayence, of which an account is given part i., vol. 

 ii., pp. 35-38, of this Journal. These prepared tubers were 

 placed in drills drawn by a hoe, and covered not more than 

 three inches deep. In the counter part of the experiment, where 

 similar tubers, but unprepared, were employed, the same shallow 

 mode of planting had of course to be observed. The conse- 

 quence was, that in both cases the produce was equally and 

 thoroughly diseased, most of the tubers approaching the pu- 

 trescent state. 



On the appearance of the disease in 1845, it was conjectured 

 that, as it manifested itself early on the underground portion of the 

 stem, the latter would be strengthened by being mostly greened, 

 from exposure to light, by shallow planting ; but from the 

 above results, it appears evident that shallow planting ought to 

 be avoided. 



In light soils the sets may be placed at the depth of eight 

 inches ; in others the depth ought not to be less than six inches. 

 Great attention should also be paid to well earthing up ; and 

 in order that a proper ridge may be formed, the rows, except in 

 the case of very early sorts, should be as much as two and a half 

 feet apart. 



