Ch.XXII.] ON POTATOES. 277 



from the August cutting apjjeared to be very great, and that from tlie 

 September cutting was calculated at not less than 93 bushels per acre *. 



This is a point which very decidedly calls for attention ; for many per- 

 sons are in the habit of regularly cutting the stems for their cows, whicli 

 they eat with great avidity, and, like any green food, occasions an increase 

 in the flow of milk : some farmers also turn their sheep in about Michael- 

 mas to feed oft" the haulm. When deferred to this period, or not until 

 about the time when the stems show symptoms of decay, it probably will 

 do no harm to the roots, and an addition will thus be made to the value of 

 the crop ; but if done earlier we apprehend there can be no doubt that it 

 will occasion serious injury f. 



The chief disease to which the potato is liable is called the curl, which 

 is known from the leaves of tlie stem becoming shrivelled, when the roots 

 are found in a state of partial decay, and finally turn rotten. Much specu- 

 lation has arisen in the farming world to discover its origin and cure. In 

 a treatise which has obtained the gold medal of the Caledonian Horticul- 

 tural Society, it is supposed to be occasioned by the use of over-ripe tubers 

 as plants ; and it is presumed that the disease would be banished entirely 

 were they constantly taken from districts in elevated situations^. It is also 

 said that potatoes grown on peatv soils are free from curl, and composts 

 with peat have been therefore recommended as manure. By some writers 

 it has been ascribed to the plants of })articular species becoming tired of 

 the soil ; by others it has been supposed that it may be communicated by 

 the sets, in the same manner as unsound seed § ; and not a few impute it 

 to a small insect, v/hich adheres to and preys upon the stem, and the attacks 

 o^which may, it is thought, be prevented by dressings of quick- lime, soot, 

 and tobacco-water || . 



By the Bath Agricultural Society it is referred to the following causes: 

 Frost either before or after the sets are planted ; planting sets cut out of 

 large unripe potatoes ; planting too near the surface, or on old worn-out 

 ground ; — and the best modes of prevention appear to consist in cutting 

 the sets from middle-sized potatoes, that were fully ripe before, and had 

 been kept dry after they were taken out of the ground, and in planting 

 them deep in fresh earth with a mixture of quick-lime^. 



The theories which have been thus elicited have, however, in various 

 instances been contradicted by the result of further experiments ; and we 

 have yet to learn to what the malady is to be attributed, or how it is to be 



* Bath Agr. Soc. Papers, vol. iv. p. 43. Another trial of a similar nature showed 

 also a i^xedX deficiency in the crop, which was also ill ripened and of bad quality where 

 the ridj^es v/ere cut, but where left untouched were excellent. — Farm. Mag. vol. ii. p. 412. 

 And in a further experiment, reported by Sir A. Grant to the Board of Agriculture, 

 " the cutting of the stems in every instance completely failed." — lb., vol. hi. p. 145. 



t A French writer of eminence says that the clustered sort of potato may be cut in 

 September without injury, but that any other sort would suffer by it materially. — Par- 

 mentier, sur les Pommes de Terre, p. 115. 



+ Dickson on the Curl in Potatoes.— Trans, of the Cal. Soc, No. i. p. 58. 



vS Thus, in one of the series of experiments made by the Rev. Mr. Campbell, to which 

 wehave already alluded, from eight potatoes, the product of a curled one, three came up 

 curled, and that in a farm where it was, at that time, a matter of difficulty to find a 

 curled plant upon which to make the trial. — Farm, Mag., vol. vii. p. 132. 



II " In proof of its being occasioned by an insect, and consequently not hereditary in 

 the tubers, ridges manured alternately with quick-lime, soot, and dung, have been found 

 quite free from curl on the two former, but on those with the dung there were some hun- 

 dreds of diseased plants."' — Farm. Mag., vol. iii. p. l.')l ; vol. xi. p. 61. 



^y See papers on the subject contained in a selection from those of the Bath Soc, in 2 

 Vols. vol. ii. pp. 40'i — tOli. 



