200 DISEASE OF THE POTATO. 



The worst evil (at least till of late years) inci- 

 dent to the cultivation of potatoes has been curled 

 leaf. The nature of the disease is not well known; 

 but it is pretty certain a remedy may be found in 

 saving for seed a portion of the previous crop before 

 it has come to maturity. For this purpose, either 

 plant late, or take up as soon as the leaves turn 

 yellow at least a fortnight before that ripeness in 

 which the tubers fall easily from the stalks, or, 

 which is better, procure potatoes for seed from a 

 high district, where perfect ripening is incompatible 

 with the climate. Exhaustion of the vegetative 

 powers is the probable cause of curl; hence the 

 advantage of premature gathering, and the propriety 

 of cutting off the flowers before the seed-berries 

 begin to form the ripening of which goes far to 

 diminish the strength of the root. It is supposed, 

 and not without good reason, that every variety of 

 the potato propagated by cuttings, as well as every 

 species of fruit trees not indigenous and renewed 

 by engrafting, have only a certain age to which 

 they can attain; hence no favourite sort continues 

 long to flourish, and hence new varieties must be 

 sought by sowing the seed. 



But a more recent evil, and far more ruinous, 

 being already of considerable extent and still pro- 

 gressive, is the perishing of the seed or sets before 

 springing up. This prevails both in Britain and 

 Ireland, as well as in the smaller islands along the 

 coasts; and though only of a few years 1 duration, 

 yet as the malady has been met by seasons differing 

 from one another in dryness and moisture, heat and 



