124 FORESTRY IN NEW ENGLAND 



Wood attacked by Polyporus schweinitzii^ has a cheesy con- 

 sistency, is yellowish in color, and is easily powdered when 

 dry. In the last stages of decay it is very brittle. These char- 

 acteristics of the diseased wood and the large, brightly colored 

 fruiting bodies are the best means of field identification. The 

 fruiting bodies when young are a yellowish-brown color, but in 

 a few days become reddish brown. The underside is some- 

 times rose colored, and if bruised quickly turns dark red. They 

 take the form of brackets, ordinarily several in number, fastened 

 one above the other, usually arising from the roots of the tree, 

 near the base of which they may be seen growing, in the months 

 of July and August. Occasionally the fruiting bodies are borne 

 on the trunk of the tree. Fully grown specimens range from 

 four inches in diameter to about fourteen inches. 



On account of its spreading underground, and entering the 

 tree unseen, the fungus is hard to detect, until in the advanced 

 stages, and hence difficult to combat. A European practice 

 is to surround infected trees and groups with a deep trench 

 which prevents the further spread of the fungus. Such a 

 method is as yet impracticable in New England, and the best 

 that can be done is to utilize diseased trees before their value 

 is entirely gone. 



The White Pine Blister Rust, or European Currant 

 Rust {Peridermium strohi)r 



Other species of Peridermium have been common in New 

 England on pitch pine and Scotch pine, as well as other plants, 

 but until recently the white pine was exempt. 



As a result of the growing enthusiasm for forest planting 

 which has spread so rapidly during the past few years, a large 

 quantity of nursery stock has been imported from Europe. 



^ For a more detailed description of the fungus see Bull. 25, U. S. Division of 

 Vegetable Physiology and Pathology, entitled, " Some Diseases of New England 

 Conifers," by Von Schrenk. 



2 See Circular 38, U. S. Department of Agriculture Bureau of Plant Industry, 

 " European Currant Rust on the White Pine in America," by Spaulding. 



