288 MAINE AGRICULTURAL EXPERIMENT STATION. I907. 



A somewhat peculiar form of the dry rot caused by this 

 fungus on potatoes from the stored crop of 1906 is elsewhere 

 described. 



The complaints from scab were much less numerous than in 

 1906, and so far as could be ascertained from observation and 

 correspondence the percentage of loss from this cause was 

 actually much less. This is in direct contradiction of the state- 

 ment frequently made that scab is more prevalent in wet sea- 

 sons than in dry. 



Internal Brown Spot of the Tuber. This is a non-parasitic 

 disease, common in some parts of Europe although but little 

 known in America. Specimens of this disease have, as yet, been 

 received from only one locality in Maine. 



Black Leg is another disease or possibly a type of disease 

 which is recorded for the first time from Maine. Since 1903 

 somewhat similar diseased conditions of potatoes have been 

 reported from Ohio, Colorado, Florida, Vermont and Canada, 

 under various names such as "potato rosette," "collar rot," "lit- 

 tle potato disease," "black leg," etc. The reader is referred to 

 the more detailed description for the characters, appearance and 

 distribution of this disease. 



A discussion of the following topics with reference to potato 

 diseases and their treatment, based largely upon the studies of 

 the past season, will be found in the succeeding pages. 



Dust sprays vs. wet bordeaux for potato blight, page 289 



Relative efficiency of light and heavy spraying; 



frequency of spraying, page 2 97 



Can our spraying methods be improved ? page 3 01 



Treating seed potatoes with formaldehyde gas to 



prevent scab, page 304 



Will" formaldehyde gas injure the seed, page 314 



Additional directions for formaldehyde gas dis- 

 infection, page 315 

 Can potato soil be limed with safety? page 316 

 Internal brown spot of the tuber, page 318 

 Surface spotting of tubers by Phytophthora infes- 



tans, page 321 



Black-leg of potatoes, page 323 



Red lead as an insecticide, page 329 



