CHAPTER XXIII. 



OTHER POINTS IN POTATO CULTURE. 



i.EOPLK have often asked me what was the cause of 

 the potato scab. To one and all I have said, these 

 many years, I do not know anything about it. I 

 have, of course, heard all the long list of causes 

 brought out by different persons. I had no faith in 

 them, because in my own experience I could think 

 of instances where I knew the cause given was not present. For 

 example, some one would lay the blame to wireworms, and I 

 know I have had smooth tubers where there were wireworms, and 

 scabby ones where there were not. It has been said that growing 

 potatoes too long on the same land will cause the trouble. Well, 

 I grubbed the trees on a certain piece of land, years ago, and put 

 it in potatoes land that never had a potato or plow in it before. 

 The first crop was awfully scabby entirely worthless. I have 

 never grown a clean crop on that piece of land, but they were 

 better last year than ever before. I plowed up my old orchard 

 last year after grubbing out the trees. It had not been plowed in 

 forty years. It was rich, mellow soil, and I expected some fine 

 potatoes. But on a certain part of it the potatoes were more 

 scabby than I ever saw before. So it goes. But one thing I am 

 quite well settled upon, viz., that horse manure in some way 

 starts the scab. I have not seen any report from any one else that 

 favored this view, but often I have seen the result. For example, 

 the spot in the newly cleared land, and also in the orchard, w r here 

 scab was so bad, was where horses had made a practice of leaving 

 their droppings for years. Perhaps it is only the accumulation 

 of manure that made conditions favorable for the scab, and the 

 same would have been the case if it had been an equal quantity of 

 cow manure ; but I think not. I have learned to be more fearful 

 of trouble from horse manure than from that made by cattle. 

 But I confess to great ignorance in regard to this trouble and a 

 great desire to find out about it. I want to know how to prevent 

 it practically. It looks now as though we were to get the 

 mastery over it before long. Scientists are telling us now what it 

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