214 MAINE AGRICULTURAL EXPERIMENT STATION. I9I4. 



the same strain of Irish Cobblers produced on the field in 

 question during two different seasons. If the disease occurred 

 in this State with equal severity generally, especially in the sec- 

 tions largely given over to potato raising, the growers would 

 have long since gone out of business and Maine would not hold 

 the position which it now has as a potato producing State. 

 However, this does not mean that what we have described is 

 necessarily an isolated case, although it is undoubtedly more 

 severe than the average. The writers predict that a more thor- 

 ough study of the situation with regard to Rhizoctonia in New 

 England and other parts of the country will show that it is by 

 no means a negligible factor as a cause of potato diseases in 

 the United States. 



By the nature of its attacks Rhizoctonia produces a most 

 insidious type of potato disease. In cases like the one de- 

 scribed not enough plants are killed outright before they reach 

 the surface to excite suspicion on account of the missing hills. 

 The one or two per cent of plants which early in the summer 

 are seen to be much under average size are accounted for as 

 due to "weak stock" or it is explained that these are the plants 

 where the seed-pieces fell with the eye down. Except to a 

 critical observer the majority of the plants may appear normal 

 and unless a period of dry weather occurs they may look rea- 

 sonably healthy and vigorous nearly or quite to the average time 

 of harvest, when the owner discovers for the first time that 

 something is wrong. 



While no other case has been seen where the disease was so 

 common and widespread as on the field at Highmoor Farm 

 during the summer of 1913, it has been found to some extent in 

 quite a percentage of the fields of Irish Cobblers which have 

 been examined in the central and southern parts of the State 

 during the past two seasons. Judging from yet too limited 

 observations upon which to base definite conclusions the disease 

 does not occur as generally or in so severe a form in Aroostook 

 County as in some sections farther south. Observations made 

 and specimens collected by Mr. C. A. Day and Mr. M. D. Jones, 

 in charge of farm demonstration work for the College of Agri- 

 culture in Washington and Penobscot Counties, would seem to 

 indicate that it is widespread and common in some parts of the 

 State and is no doubt an important factor in cutting down the 



