37 



Control. — No satisfactory means of controlling this disease is known. Mr. 

 Giissow states that under no circumstances should the unboiled or decayed potatoes 

 of a diseased crop be given to pigs or other animals as food, nor should they be 

 thrown on the manure pile. They should be burned or buried with unslaked lime. 



Land that has borne potatoes with the Wart Disease should be thoroughly 

 cleared of all diseased potatoes, and treated to a coating of unslaked lime at the 

 rate of four or five tons per acre. Moreover, potatoes should not be planted on 

 an infested field for seven or eight years. Under no circumstances should seed 

 potatoes from a diseased crop be used. 



WHITE-PINE BLISTER-RUST.— Cronartium ribicola.— This disease has 

 also its origin in Europe where it has done a great deal of injury to White-Pine. 

 It has been reported from various parts of the United States where it has been 

 imported in nursery stock from Germany, and there is a danger that it may become 

 established as a permanent pest and spread to the White-Pine plantations of 

 Canada. 



The Fungus. — Like many other rusts this fungus lives on two entirely differ- 

 ent hosts — one stage on the White and allied 5-leaved pines; the other on the 



Pine-Currant Ruat. 



leaves of wild and cultivated Currants and Gooseberries. It cannot spread from 

 pine to pine, but it can from currant or gooseberry to currant and gooseberry 

 by means of the summer spores. Two kinds of spores are produced on the leaves 



