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THE CONTROL OF POTATO DISEASES. 



H. T. Gussow, Dominion Botanist. 



It is a difficult matter to give an actual estimate of the annual losses 

 for the Dominion, due to plant diseases affecting the potato crop. Judging 

 from the considerable number of cases, the total loss must be enormous in 

 some years particularly. 



The loss from the so-called "storage rots" amounted in some cases 

 to 40 percent; The yield, owing to the use of diseased seed, as far as can 

 be judged from "misses" in the fields, has been occasionally reduced by 

 some 30 percent, and diseases affecting the growing plant may also cause 

 considerable damage to the crop. 



In order to prevent such loss and make the cultivation of potatoes 

 more profitable, it is necessary to follow strictly certain lines laid down for 

 the elimination of diseases, when it is reasonable to expect that the diseases 

 will be eventually exterminated or reduced to a minimum. Any objections 

 a farmer may have to carrying out the following suggestions will disappear 

 when he finds from experience that their observance results in a greatly 

 increased yield and higher profits to himself. 



A. The Diseases of the Seed Tuber.** 



1. The presence of the following diseases or insect pests, scheduled 

 under the "Destructive Insect and Pest Act" of the Dominion of Canada, 

 shall disqualify any lot of potatoes for seed purposes, viz.: Potato Canker, 

 Powdery Scab and Potato Tuber Moth.* 



Potato Canker is not known at present in Canada. 



Powdery Scab occurs in the Maritime Provinces; no cases of this disease 

 have been observed west of the Province of Quebec. In order to prevent 

 the dissemination of this disease, all potatoes grown in the "infested area" 

 are being officially inspected and certified before shipment. 



** (Attention is here directed to Farmers' Circular Xo. 4 entitled "Potato Diseases 

 transmitted by the use of Unsound Seed Potatoes," which shows the more common diseases 

 of the potato tuber in natural colours, and which will be found useful for reference when 

 reading these lines. Copies may be obtained free of charge from the Publications Branch, 

 Department of Agriculture, Ottawa.) 



* See Circular Xo. 6 entitled "Regulations under the Destructive Insect and Pest Act 

 governing the importation, sale, shipment and exportation of the Common or Irish Potata 

 (Solanum tuberosum L.);" for copies apply to the Dominion Botanist, Experimental 

 Farm, Ottawa.) 



