104 FARMERS' INSTITUTES. 



where the soil is generally light, show that the rot there is nearly or quite 

 unknown. 



BRIEF HISTORY. 



The potato rot is not new. Nearly every year the crop rots to come extent 

 in one locality or another. Little notice was taken of it, however, until 

 1845, when the first serious failure of the crop froQi this cause in that and 

 the year immediately following, caused extensive famines in Ireland, England 

 and Germany. Previous to that time considerable injury had been caused in 

 some years by " dry rot," " wet rot" and " curl," which are now attributed 

 to the same disease. Kot, apparently the same as our potato disease, appear- 

 ed in Canada in 1844, in Germany in 1842, in Scotland in 1832, in parts of 

 France in 1816, and at various other times and places, and has apparently 

 existed to some extent ever since the potato was brought into cultivation. 

 It may have originated in the home of the potato in the warmer parts of 

 America. Joseph Acosta, a Jesuit, observed in Peru as early as 1571 that 

 the tubers often spoiled in the earth from " blight or mildew " during or 

 after cold, bad weather. On the table lands around Bogota, according to 

 Boussingault, the potato spoiled in moist situations every year, and in wet 

 seasons spoiled everywhere. 



APPEARANCE OF THE DISEASE. 



The disease makes its appearance about the last of July or early part of 

 August, usually after a period of damp, muggy weather. Its appearance in 

 1845 is thus described by the Commissioner of Agriculture of the province 

 of Groningen, Holland: " The intense heat of the summer was succeeded 

 by cold, rainy weather from the middle of July to the end of August. On 

 July 21st and 22d there was an extensive fog, and on the 28th the first blight 

 appeared." In England the season was also unusually moist. From the 

 first to the tenth of August it was hot and humid, causing an unusually 

 vigorous growth. This was followed by cold, and in some cases frost. 

 Within ten days the potatoes were struck with blight all over England. Not 

 long since I Avas talking with a farmer who came from Ireland in 1847, in 

 which year the rot was also severe, and he described a similar condition of 

 weather there at the time of attack. The season had been moist and the 

 potato vines were exceedingly vigorous, of a brilliant green and covered the 

 whole ground. There had been a dense fog which lasted two days, after 

 which the sun came out hot, and the vines soon blackened and died as fromj 

 a heavy frost. The tubers, at the time the tops died, were uninjured, but 

 in a few days when they came to dig, two men in all day could not find 

 enough sound potatoes for supper. The rot first appeared in the tubers 

 just beneath the skin, but soon, as he described it, "melted right away to 

 the center." 



All agree that the disease first makes its appearance on the tops. It 

 shows first as small frosty spots, usually on the under side of the leaf. As 

 the spots enlarge the centre becomes brown and dies, and the leaf or a part 

 of it withers. It is then that the disease is usually first noticed. Soon the 

 stem is attacked, and usually, in a week or more, according to the weather, 

 the tubers also. Occasionally, in case the weather turns cool and dry, the 

 affected leaves and stems dry up, and the disease goes no farther, so that the 

 tubers escape. When the tubers are attacked, the disease first shows as fine,, 

 brown specks and streaks just beneath the skin, and from the spot first at- 



