DEPARTMENT OF FORESTRY 



Editor \ ^'^°^" -J"^" ^' Briscoe, 



I Orono 



THE WHITE PINE BLISTER RUST 



(Cronartium ribicola Fischer) 



By John M. Briscoe 



Of all the parasitic fungi, that known as the White 

 Pine Blister Rust is giving most concern to foresters and 

 naturalists at this time. This is so, not because it threatens 

 the present crop of mature or nearly mature white pine, 

 but because it jeopardizes the future of this valuable timber 

 tree species. 



The fatal results of this disease are being found in in- 

 creasing abundance throughout the natural range of the 

 white pine in the northeastern states. It is also established 

 over a large area in Wisconsin and Minnesota. 



The fact that the disease is fatal to young pine is be- 

 yond dispute. Convincing evidences are all too abundant at 

 the present time, and may easily be inspected by anyone 

 who is at all inclined to be skeptical as to the actual damage 

 done by the disease and its effect on the trees attacked. 



The native pines are fast becoming generally infected. 

 Extensive surveys by the Bureau of Plant Industry showed 

 that 16 per cent of the trees examined were already diseased. 

 In addition there are local areas in Maine, New Hampshire, 

 Massachusetts, and New York where the infection now runs 

 from 33 percent to 67 percent of the present stand of young 

 pine, and trees completely girdled and killed by the disease 

 may be found up to as much as 10 inches in diameter. Some 

 of these areas are of wide extent. 



After looking over a single one of the many badly in- 

 fected areas where the disease already has obtained a firm 

 foothold, no one will doubt the damage that can be and is 

 already being done to our future crop of this most valuable 

 species. 



Undoubtedly more has been written on the value of the 

 White Pine for this region than on any other species. Advice 

 for obtaining future crops both by natural regeneration and 

 by planting has been given and is still being given in abun- 

 dance; but all such efforts will be rendered futile if provi- 

 sion is not made for the eradication of all species of currants 



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