3l6 MAINi: AGRICULTURAI, EXPERIMENT STATION. I909. 



8 to 10 per cent. The average injury from the field possibly 

 not being over 3-5 per cent. The portions of the field planted 

 to other varieties of home grown seed had no 'blackleg' what- 

 ever. I have not been able to find any 'blackleg' in the trucking 

 fields in which home grown seed . was used. The general 

 opinion is that the disease was introduced with the seed potatoes 

 but this has not been definitely proven." 



Professor J. B. S. Norton writes, in answer to an inquiry, 

 that during the past season he has seen one case of blackleg on 

 a field planted to Maine seed in Somerset County, Maryland. 



A letter from Professor G. E. Adams of Kingston, Rhode 

 Island, states that in 1907 he found 5 hills of potatoes which 

 appeared to be suffering from blackleg. "These potatoes were 

 grown from seed which was obtained from England in the 

 spring of that year." This is interesting as suggesting the possi- 

 ble origin of the disease in Maine. Harrison's account of the 

 distribution and amount of damage produced by this disease in 

 Canada,* even though we disregard the large amount of bacterial 

 soft rot of the tuber following invasions of the late blight fun- 

 gus Phytophthora infestans and the ordinary decay caused by 

 this fungus itself, which he has apparently attributed to the soft 

 rot associated with the stem-disease, indicates that blackleg is a 

 more common and destructive disease in certain provinces of 

 Canada than in any section of the United States thus far 

 reported. Importation of seed stock from England would 

 naturally be more common in Canada than to the United States. 

 Therefore, it is conceivable that tubers infected with this dis- 

 ease have from time to time and at various places been intro- 

 duced into Canada from England. Once in Canada, particularly 

 in New Brunswick, the spread of the disease to Maine was a 

 comparatively easy matter and a logical sequence, for Maine's 

 greatest potato district borders on this latter province and quite 

 a percentage of the potato growers of this section are former 

 residents of the adjoining sections of Canada. 



There is evidence that the introduction of the disease into 

 some parts of Maine, at least, is by no means a mat- 

 ter of recent date. Many practical men when the diseased 



* 1. c, pp. 34 and 391. 



