2 MAINi: AGRICUIvTURAI, EXPE;RIMENT STATION. I909. 



However, in the portions of the State where potatoes are the 

 main commercial crop this lack of rain was not enough to 

 reduce the crop, but just sufficient to hold the late blight in 

 check. Early blight, Alternaria solani, on the contrary found 

 ideal conditions for development upon the plants already weak- 

 ened by dry weather, and consequently did much damage on all 

 but the most thoroughly sprayed fields. This was particularly 

 the case in the central and western parts of the State where the 

 drouth was more severe and spraying is less generally practiced. 



Stem and Tuber Diseases. Last year the occurrence of a 

 stem and tuber disease new to Maine was noted and the appear- 

 ance of the affected plants described under the name of Black- 

 leg.* 



It was stated that the evidence so far obtained indicates that 

 the disease is of a bacterial nature. During the past summer, 

 cultures of bacteria have been isolated from stems of potatoes 

 attacked by black-leg, which are able to cause a rapid and com- 

 plete decay of potato tubers and, on inoculation, have produced 

 the characteristic black-leg disease of the stem, thus confirming 

 the diagnosis. The organisms thus secured are now being 

 studied. 



Another disease of the stem and tuber which is usually desig- 

 nated as the Fusarium dry rot caused by the fungus Fusarium 

 oxysporium, Schlecht. has been found for the first time in 

 Maine during the past summer. It is well known that this dis- 

 ease,, and it is probable that black-leg as well, is disseminated by 

 means of seed tubers from infected fields, therefore, tubers from 

 fields showing either of these diseases should not be used for 

 seed. Fortunately neither disease is very widely distributed in 

 Maine, and prompt measures taken at this time will restrict their 

 spread and possibly lead to their eradication. 



Both the Fusarium dry rot and black-leg are fully described 

 in a circular issued by the Station, entitled How to Fight Potato 

 Enemies. This circular can be obtained by any potato grower 

 or dealer on request addressed to the Experiment Station. 



Maine seed potatoes are probably as free from such diseases as 

 any which are shipped South for planting and the writer believes 

 that for many reasons they are much cleaner in this respect than 



*Me. Exp. Sta. Bui. 149, p. 323. 



