THE FAI^MliR'S MAGAZINE. 



487 



THE CULTIVATION OF THE POTATO, AND ITS 



FROM DISEASE. 



PREVENTION 



BY PROFESSOR TANNEU. 



The value of this root was never fully known un- 

 til the appearance of the .well-known potato-disease 

 caused great losses, and much disappointment to 

 accompany its general cultivation. The alarm which 

 at first filled almcst everyone's mind has, since 

 then, subsided into calm, and every succeeding year has 

 added fresh information upon this peculiarly interesting 

 topic — the potato disease. I purpose, therefore, to 

 notice the general character of the disease, and then 

 proceed ta (lie field-management of this crop, in differ- 

 ent districts, and the modifications in practice, which 

 have been introduced in consequence of the disease. 



In 18J3 the potato crop in America was much in- 

 jured by disease, and some few instances were observed 

 in England in this and the following year. It remained 

 for 1845 to reveal the fearful loss which this disease was 

 capable of producing. The weather had been remarkable 

 during the summer of this year for a large amount of 

 moisture, both in the form of vapour and in rain, ac- 

 companied with a more than usually clouded sky. From 

 the 1st to the 10th of August the sun gained more power, 

 and the moist atmosphere, combined with this increased 

 warmth, caused a luxuriance of growth in the potato- 

 crop, almost unparalleled. These hot and humid days 

 were after this date succeeded by cold, and la some 

 places frosty nights, and the consequence was that the 

 potatoes were very generally struck with disease, so that 

 within ten days almost every part of England joined in 

 the panic-stricken cry " The potato -crop is destroyed." 

 Those districts in which the potato formed the staple 

 food were threatened with famine, and but for the 

 praiseworthy exertions then taken by all classes of 

 society, the horrors of famine would have been far 

 greater than they were. 



The loss and alarm thus occasioned led to the substi- 

 tution of other crops ; but in Ireland, where the sole 

 support of the greater part of her population was pota- 

 toes and milk, this could not be accomplished imme- 

 diately, and for two or three years great misery and dis- 

 tress prevailed. The Royal Agricultural Society of 

 England was actively engaged, immediately after the 

 appearance of the disease, in stimulating the introduction 

 of remedial measures, and through her officers and other 

 scientific men, investigations were instituted into the 

 cause of the disease. From that day to the present 

 time some degree of mystery has shrouded the cause, 

 although many imagined that they knew the cause, still 

 exceptions could in each case be produced to show 

 that other agencies had been in operation. 



These investigations followed by subsequent examina- 

 tions bring the cause under that extended term " at- 

 mospheric agency." Those who advocated that guano 



and other manures, or the growth of fungi, or the de- 

 velopment of animal life, had in their respective opinions 

 been the cause, have since then seen cause to regard 

 them either as results, or else as promoters of the 

 disease rather than the cause. The true cause is, doubt- 

 less, wrapped up in the term ' ' atmospheric agency ;" and 

 until we are more fully acquainted with the subtile in- 

 fluences here combined, and have some clearer views of 

 their indi"idual powers, we shall be imable definitively 

 to explain the agency employed. There are, however, 

 many who will be disposed to go with me even beyond 

 this point, and view this disease as a remarkable visita- 

 tion of Providence, intended to produce the most impor. 

 tant results, and accomplished by the command of Him 

 who rules and governs the operations of Nature, and at 

 whose will the powers of the atmosphere became the 

 agent employed for this purpose. 



It would be a tedious task were I to recount to you 

 the various causes which have been named as pro- 

 ducing the potato disease. I shall restrict myself to 

 that explanation which I consider bears upon it the im- 

 press of truth and which admits of proof. But before 

 we notice this, it may be desirable to record the in- 

 fluence exerted by the disease. There is a great diversity 

 of opinion as to .whether the leaves, stem, or roots are 

 the first affected. It admits of easy explanation why 

 this difference of opinion should exist so far as regards 

 the leaves and stem ; be that as it may, the plant be- 

 comes discoloured in a great or less degree ; the leaves 

 and stalks soon fall, becoming rotten and particularly 

 offensive ; the roots, after showing spots in the skin, 

 gradually decay, and in the change become dark in 

 colour, mucilaginous or gummy in condition, and finally 

 become a putrescent mass. These changes take place 

 with greater or less rapidity according as other circum- 

 stances promote or retard the action. 



In assigning a cause for this disease, I am disposed to 

 accept that given by Professor "Way, viz., that the sap 

 of the potato when exposed in the leaf to the atmo- 

 sphere became altered in its character by the atmospheric 

 agency producing the disease. As this altered sap 

 passed through the plant, so it carried with it the ele- 

 ments of decomposition which produced the results de- 

 scribed above. To enable the general reader to under- 

 stand this as clearly as possible, I must give some ex- 

 planation of the composition of the potato. The root 

 contains a very large proportion of starch, which is the 

 natural supply of food for the plant's early growth. 

 The eyes or germs of the potato, which are observable 

 upon the surface, are the points from which the new 

 plant springs. When these germs are about to grow, 

 fond is necessary for enabling them to exercise the 



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