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I AMERICAN FORESTRY 



VOL. XXIV 



AUGUST, 1918 



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NO. 296 



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BATTLING THE PINE BLISTER RUST 



BY S. B. DETWILER 



THE blister rust battlefield stretches from coast to 

 coast. Introduced into the United States from 

 Germany and other European countries less than a 

 score of years ago, this disease of our white pine trees is 

 well established in the New England States and New 

 York, is attempting to get a foothold in Minnesota and 

 Wisconsin, and without constant vigilance, it will find its 

 way into the sugar pine and white pine forests of the 

 far West. 



Fighting the blister rust is less spectacular than fight- 

 ing the Germans, but it is almost as difficult and neces- 

 sary. Enormous as are present demands on our timber 



supplies, they will be greater in the future. The goal 

 in the fight against the blister rust is the preservation 

 of one of the noblest groups of trees native to American 

 soil the white pines. Not only are these trees of sur- 

 passing usefulness because of the exceptional qualities 

 of the wood, but their comparatively quick growth and 

 adaptability for planting and management make them 

 especially valuable to the forester, who looks to the needs 

 of the future. European experience with the blister rust 

 indicates that its unrestricted spread in this country 

 would be a catastrophe. The native white pine in the 

 Eastern states is valued today at $186,000,000. The 



Courtesy of IV. S. Carpenter, New York Conservation Commission 



CURRANT LEAVES INFECTED WITH BLISTER RUST 

 The leaf with the deep rounded notches at the left in the picture is that of a flowering currant, the others ire ordinary cultivated red currants. 

 The dark spots (on the under sides of the leaves) are the fruiting bodies of the blister rust fungus. White Pine Blister Rust is caused by a 

 fungus (a parasitic plant) which was brought from Europe on nursery stock. It begins life in the young bark of hve-needled pines and pro- 

 duces blisters there that are filled with dust-like seeds called spores. The spores are blown in May and June to currant and gooseberry leaves 

 and grow into a rust on the under sides of the leaves. After a period of growth on the leaves, another form of seed-like spores are developed 

 and are blown in August and September to healthy pines. The life cycle then begins all over again. Spraying will not check its spread. Ihe 

 only preventive measures are the cutting and burning of diseased pines and the eradication of all currants and gooseberries in mtected localities. 



