4 MAINE AGRICULTURAL EXPERIMENT STATION. 



with the fact that powdery scab is quite widely scattered in 

 Canada, makes a strong case against that country. However, 

 before we accuse her of being the entire cause and source of 

 our troubles', one very important fact which we did not know at 

 first, should be taken into consideration. It now looks as though 

 powdery scab is a disease, the distribution of which is quite 

 definitely limited by climatic and soil conditions. It may be, 

 and there is considerable reason for believing this to be a fact, 

 that in America it will only develop in the cooler, moister cli- 

 mate of Canada and along the very northern border of the 

 United States. There is no doubt that thousands of bushels of 

 potatoes infected with the disease have in recent years been 

 used in the South for seed, yet a most careful search has failed 

 to reveal any in the crops they have produced there except a 

 few tubers at or near Hastings, Florida. It has not been found 

 in the southern part of our own state even, except in the ex- 

 treme southeast where the summers are. usually relatively cool 

 and wet. Its absence from the remainder of the state can 

 hardly be claimed to be due entirely to freedom from contagion. 

 It seems almost beyond belief that infected potatoes have not 

 been planted from time to time in that part of Maine which is 

 now thought to be and apparently is free from the disease. 



Blackleg is another undesirable emigrant which Europe, 

 especially England, passed along to us by way of Canada. We 

 have evidence also in certain instances of direct importations 

 of blackleg and powdery scab from European countries. Un- 

 doubtedly such importations were numerous in the years just 

 previous to the time when the potato quarantine became effec- 

 tive. In the fall of 1913 I found powdery scab abundant in 

 some European shipments of potatoes which arrived in Boston, 

 and the same condition was found by the Government patholo- 

 gists when they looked into the situation both iii Boston and 

 in New York City. 



Blackleg was first reported in America in 1906 but it had 

 apparently been recognized in Canada a few years previous to 

 this. Undoubtedly it occurred in Maine some years before it 

 was recognized and described by myself the first year I was 

 here, or in 1907. 



Within our own country several important developments in 

 the potato industry have taken place during recent years. Po- 



