32 



MR. TOWEKS ON THE POTATO DISEASE. 



atic acid. I have witnessed nothing similar in the totally 

 decayed tubers of 1846, they being- altogether rotted as if by 

 immersion in water. The labourers here remark the same cir- 

 cumstance, saying, that "now they have the wet rot, whereas 

 last year it was the dry." 



In 1845, after permitting the store to remain quiet for a 

 month, I had it looked over, and removed another quantity of 

 decaying tubers. It was then I perceived, as others had re- 

 marked, that strong sprouts appeared at the rose or crown ends, 

 even when the fibrous end of junction with the plant was greatly 

 affected. I selected a bed of good loam for seven eight-yard rows. 

 Furrows were made, and the sprouted decaying potatoes were 

 planted in them one foot asunder, all of them dusted over along 

 the course of the drills with dry air-slaked lime. The course 

 of each row was sprinkled with coal -ashes over the covering 

 earth. Had frost occurred, the rows would have been further 

 protected, but it did not, and broad beans were dibbled in among 

 them, about ten inches apart. Notwithstanding the precocious 

 excitability of the eyes, a phenomenon which has not as yet 

 been observed (October 19, 1846), the shoots were so tardy in 

 the spring, that, fearing a total decay, I set early sound kid- 

 neys in the intermediate spaces, and these rose before the No- 

 vember sets. At length the shoots of the latter appeared, with 

 here and there a blank, and both varieties progressed together, 

 as also some of the beans ; but as a burning heat with aridity 

 was established by the 22nd of May, the bed became droughted, 

 and when new potatoes were wanted, the ground and the lime 

 with which the potatoes were covered were found dust dry. A 

 second progeny, some not larger than peas, had been produced 

 from pre-ripe young tubers, themselves not so large as walnuts. 

 Both plantings remained healthy till the first week in August : 

 then the dark-brown spot, with mildew round it, on the under 

 side, appeared in the leaflets. When the stems became feeble, I 

 pulled the whole up entire. 



Results. — The kidneys failed as to yield, but very few were 

 diseased. Some rows remain in the ground, which now is so 

 poached with perpetually recurring rains that it is difficult to 

 move it : the crop from the defective tubers was fine flavoured. 



2. A row of very early kidneys had been left in 1845. The 

 tubers were therefore deep, but they produced extremely vigo- 

 rous shoots, which remained healthy till August 3. On their 

 foliage I first observed the spot and the accompanying mildew. 

 Under a powerful lens this fungus was most beautiful. Upon its 

 fibres, spores were seen of an oval form ; the fibres rotated if 

 touched by the breath, and some spores were then seen to ex- 

 plode. Though the foliage and stems failed rapidly, I found 



