The Potatoe Plague. 65 



failure in the potatoe crop," says Mr. Thompson, "I paid 

 more than ordinary attention to the selection of seed, and in 

 1840 planted sixteen acres with potatoes, making choice of 

 two kinds of round red varieties, both of them new to my land. 

 The gentleman from whom I obtained them, having two farms, 

 one of stiff, the other of light land, had changed his sets 

 regularly from one to the other. I planted them on a sandy 

 loam, which was in a high state of cultivation, and my reason 

 for planting it with potatoes was solely because I was aware 

 if sown with corn it would be so lodged as to be nearly 

 worthless. They were planted in the last week in April. I 

 naturally expected a heavy crop, but was much disappointed, 

 as symptoms of curl soon appeared. This increased, and 

 though few of the plants perished, nearly the whole were 

 unhealthy. I was so much surprised at the appearance of 

 curl that I watched and examined the plants at several 

 periods of their growth, taking up roots here and there 

 wherever I observed one either better or worse than its 

 neighbors* The appearance of all those affected was nearly 

 the same. The set, as long as the weather was dry, crum- 

 bled and perished, the disease seeming to proceed from 

 certain spots or pits as centres, and gradually destroying the 

 whole set. The cut sets were the worst, and the decay 

 always commenced from the cut side of the set, but the 

 whole ones also suffered. 



As soon as the weather became wet, these appearances 

 changed, and the diseased portion of the set resembled a 

 sponge, which after a short time became black and offensive. 

 The effect, on the plant was well marked. Wherever the 

 disease had made a decided impression on the set, the stalks 

 of the plant were marked with brown streaks and patches, 

 and evidently showed that the juices which they were con- 

 ducting from the set were vitiated and noxious. The part 

 of the stalk to which I directed my attention was that under- 

 6* 



