REPORT OF THE SOCIETY 43 



PLANT DISEASES OF 1922 IN WESTERN QUEBEC. 

 By B. T. Dickson. 



In prfesenting this account of the pJant diseases observed during the 

 season of 1922 the writer feels impelled to explain that the tack of more exact 

 data regarding prevalence and economic importance is due to the author's 

 undesired vacation in hospital. It is felt, however, that even a somewhat 

 fragmentary account is of value in helping to survey the Dominion as a whole. 

 I wish to thank Mr. J. G. Coulson of this Department for obtaining mUch of 

 the information herein recorded. 



Potato. — Early blight {A. solani) was quite common and in August- 

 September the foliage was considerably spotted. The spots were not large 

 and rarely coalesced and it is not likely that the resulting loss in yield was 

 appreciable. 



L ate blight (P. injestans) was not seen to any extent. 



Mo^a,ic was present, as was Leafroll, but not serious, although aphids 

 were found in nambers during mid-October. 



Uppperburn was prevalent during September and leaf-hoppers were 

 common on late varieties. 



Black dot disease. — This disease, which is being studied by the aulthor 

 was of frequent occurrence during the latter part of this season. In some 

 fields it was present to the extent of 5%. It is impossible to say yet whether 

 it causes serious injury but it was usual to find affected plants dying down two 

 or three weeks earlier than healthy ones in the same plot. The 'root system s, 

 stolons, and ground-level stem tissues are attacked and killed. The develop- 

 ment of tubers depends upon the stage at which the stolons are affected. 

 Manj'^ tubers with the black-dot sclerotia on the surface were found. 



Tomato. — Mosaic was present but not to the same extent as during 1920 

 or 1921. 



Leaf blight, caused by A. solani, was very common during late August 

 and September and spotting of the fruit with a subsequent rot occurred in 

 September. 



Bean. — Anthracnoge {C. lindemuthianum) and blight {Ps. phaseoli) were 

 prevalent, the season being ideal for their development and rapid spread 



Mosaic less noticeable although frequent. 



Stem-rot and wilt caused by S. lihertiana was of local occurrence but 

 quite comonon. 



