REPORT OF THE SOCIETY 67 



and immediately burnt. Gummed bands applied to the trunk will protect the 

 tree very effectively against many marauders from outside especially cater- 

 pillars. 



The measures outlined above should help to prolong the beauty of our orna- 

 mental trees. 



DISEASES OF THE POTATO * 

 By B. T. Dickson, B. A., Ph. D.. Professor of Botany, Macdonald College 



Introduction 



The potato crop is of prime importance to Cani^da and therefore the impor- 

 tance of a knowledge of the diseases of the potato need not be stressed here — 

 it should be taken for granted. Without quoting statistics, the losses from 

 potato diseases amount to millions of dollars every year. This means that 

 every year a percentage of the seed planted is useless, that a part of every 

 acreage is wasted, that labor is not used to full advantage and, finally, that 

 the grower suffers a direct financial loss whether he is growing potatoes for 

 sale or use. 



In dealing with this series the diseases will be considered in the order now 

 given. 



1. Diseases in which insects are the agents of infection or in which insects 

 are the direct cause: — 



(a) Hopperburn. 



(b) Mosaic and mosaic dwarf. 



(c) Leaf roll. 



2. — Disease caused by a myxomycete: — 



(a) — Powdery scab (Sponffospora subterranea) . 

 3. — Disease caused by bacteria : — 



(a) Black leg (Bacillus atrosepticus.) 

 4. — Diseases caused by Phycomycetes: — 



(a) Black wart or potato canker (Ch-ysophlyctis endobiotica.) 



(b) Leak (Pythium de baryanum). 



(c) Late blight (Phytophthora infestans). 

 5. — Disease caused by an Ascomycete: — 



(a) Wilt and stem rot (Sclerotima libertiana.) 

 6. — Disease caused by a Basidiomycete : 



(a) Dry stem rot and black scurf {Corticium vagum). 

 7. — Diseases caused by Fungi imperfecti: 



(a) Early blight {Alternaria solani). 



(b) Wilt (Fusarium oxysporum). 



Printed by permission of Scientific Agriculture 



