68 PROTECTION OF PLANTS, 1915-16 



We have here, then, a disease, the Hfe history of which may be summed 

 up as follows: — 



(A) On the pine. 



1. Lives on 5-leaved pines only. 



2. Produces cankered areas with discolored swellings in limbs. 



3. Limbs are girdled and killed; seedlings are killed rapidly; adult 

 trees more slowly. 



4. Spores produced in early spring from the canker blisters may 

 infect nearby currants, but not pines again. 



(B) On Currants. 



1. On all wild and cultivated currants and goosberries; black 

 currants particularly susceptible. 



2. Leaves only affected; small orange rust pustules on the under 

 sides of the leaves. 



3. Spores from these pustules spread the disease during the summer 

 to other currants (but not to pines). 



4. In fall spores capable of infecting pines appear on the leaves. 



5. Rust probably dies out each winter on currant and has to be 

 started in spring from pines again. 



It is well established that the Blister Rust was brought to this continent 

 from Germany, Holland and France, on white pine seedlings imported for 

 nursery purposes. Both in the United States and Canada numerous infec- 

 tions in different districts have been definitely traced to some seedling 

 pine afifected by the disease, and either standing in the nursery row or 

 planted out in shrubberies or forestry plots. In only one case in Ontario 

 has the disease been found on native grown white pines, but the amount 

 of infection in the small woodlot in question was so great that it makes one 

 shudder to think of what would be the result if the disease ever gained a 

 footing in our large forest areas. 



So far as I know there is none of the disease outside of the Province 

 of Ontario. In that province the affected area includes, generally speaking, 

 the fruit district between Niagara Falls and Hamilton, and extends along 

 the northern shore of Lake Ontario betw'een Toronto and Hamilton as far 

 as Oakville. In addition there are isolated areas at Brantford, Guelph, 

 Dutton (Kent Co.), and Bowmanville (Durham Co.). 



Judging from the experiences of the U. S. Forest Service in stamping 

 out the disease in a number of areas in that country, we may not find 



