74 POTATO CULTURE. 



of a scabby crop, or handled all in the same boxes, yon may 

 possibly and even likely have got the disease germs on your 

 selected tubers. Again, another thing has been learned : 

 The disease will remain in soil where once it has been. How 

 long, we do not know. That it will stay, all ready for busi- 

 ness, three years, I know. The fungus, as we will call it, 

 lives along, waiting for more potatoes to work on. Now, 

 don't you see what we practically want ? First, something 

 that will kill those germs on the seed, if any are present ; 

 and, second, something to end the germs in the soil when 

 these are troubling us. Sometimes these germs in the soil 

 do not come from raising potatoes directly. They certainly 

 originate in some other way. The tendency will be toward 

 getting them in the soil by continuous growing of the crop 

 on the same land. There is less danger of all such troubles 

 where regular rotation is practiced. But we once cleared oif 

 some timber, grubbed out the stumps, and put in potatoes 

 without any manure, and on one place the tirst crop was 

 scabby, and every succeeding one has been, no matter how 

 nice seed was put in. Two years ago we plowed up land 

 where we had grubbed out an old orchard. It had certainly 

 had no potatoes on it for forty years ; but on part of the land 

 they were horribly scabby. How did the disease get there ? 

 Well, it is easy enough to think how it might. Some cow 

 might have been fed parings of scabby potatoes, and left her 

 manure in these places. I simply give you this as a hint of 

 how much trouble we may be put to in the future by this 

 fungus. By feeding potatoes to our stock we may fill the 

 manure with the germs, and then scatter it over our land. 

 As stated in another chapter, fresh manure is more likely to 

 cause an increase of scab than old rotten manure. I have a 

 strong impression that horse manure is worse than cow 

 manure. But on most of these points we are yet in the 

 dark. We have no certain known way yet of destroying 

 germs that are in the soil. I have met a number of growers 

 who have faith in the use of lime for this purpose. Years 



