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A STEM ROT DISEASE OF POTATOES. 



(Corticium vagum, B. & C. var. Solani, Burt) 



W. Lochhead, Macdonald College. 



A Stem Rot Disease of potatoes, known formerly as Rhizoctonia from 

 its characteristic sterile mycelium which forms no spores, was quite severe 

 in some localities in the Province. The writer had the disease under 

 observation in the potato plots at Macdonald College, and was able to 

 study some of the characters of the sterile form. 



This disease is known in different countries as "Black Rot," "Little 

 Potatoes" and "Stem Rot." It has been reported from Europe and from 

 many States of the American Union, particularly of the Middle West, and 

 is capable of doing much damage. It attacks the stem below the surface 

 of the ground destroying the bark and frequently completely girdling the 



Fig. 1— "Little Potatoes'' on a stem attacked with Rhizoctonia. 



