106 WILL TUBERS GROW AFTER THE DESTRUCTION 



the ground immediately covered over with soil as recommended. 

 Besides these, the north half of a row was cut over and covered 

 in the same way, whilst the south half was left ; and another row 

 had the south half cut over, its other half not. In short, due 

 precautions were taken to insure a fair result. On the 30th of 

 August the rows cut over were dug up, and the produce weighed 

 and compared with that from adjoining rows of Jersey Blues of 

 which the stems had been allowed to remain. The rows were 

 2^ feet apart, and 24 feet in length. The average sound pro- 

 duce of rows cut over was 4 lbs. 5^ ozs., which is at the rate of 

 ] ton 8 cwt. 19 lbs. per acre. The average sound produce of 

 rows not cut over was 28 lbs. 9£ ozs., which is at the rate of 

 9 tons 7 cwt. per acre. Hence, the difference in favour of stems 

 not cut down amounts to 7 tons 18 cwt. 93 lbs. per acre. With 

 regard to diseased tubers, there were none in the rows cut down. 

 In the rows not cut down the diseased portion averaged 13 ozs. 

 per row, being at the rate of o cwt. 29 lbs. per acre. 



" It may be proper to observe that the potato plants experi- 

 mented upon had not been earthed up, so that they were cut 

 over by the ground-level. On taking them up, it was found 

 that the portion of stem left under ground was quite dead. In 

 some cases a fresh shoot had pushed ; and such shoots were found 

 to be making fresh roots, and commencing to form runners for 

 tubers ; of course these would be too late for attaining either 

 size or maturity of any importance. Their tops were fresh ; but 

 had no living connexion with the tubers that had been formed 

 from the original stems. These first-formed tubers were small, 

 but firm and sound. Their growth must have been almost en- 

 tirely arrested by the cutting down of the stems. The soil was 

 dry. In former years, in moister soil, I have observed, since 

 the disease commenced, that the tubers in many cases increased 

 considerably in size after the total, but premature, decay of the 

 tops. 



" The results of the experiment are unfavourable to the pro- 

 posed method of cutting off the stems ; for although the tubers 

 from the plants deprived of their foliage were sound, yet they 

 were obtained at the loss of more than five-sixths of the crop 

 which would otherwise have been produced. 



" On referring to vol. iii. p. 180 of this Journal, it will be seen 

 that some experiments were tried in the Society's Garden in 

 1846, with reference to cutting off the stems as soon as disease 

 manifested itself upon them. It was found to have a somewhat 

 beneficial effect where the tubers had previously acquired consi- 

 derable size , but was found to have a diminishing effect on the 

 amount of produce where the crop was not so far advanced." 



From this it would appear that nothing is gained by the ope- 



