FOREST INSECTS AND FUNGI 129 



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 strobi). 1 



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 was imported from Europe. In June, 

 1909, some of the stock thus imported into New York state was 

 found to be infected with this fungus and on examination it was 

 discovered that stock imported into other states was likewise 

 diseased. In fact the fungus has been found on trees imported 

 several years previous to 1909. In nearly all cases the diseased 

 stock has been traced to one European nursery, that of J. Heins 

 Sohne, of Halstenbek, Germany. 



The disease has spread widely from several of the diseased 

 plantations and many new sources of infection have been located 

 in the last two years as a result of systematic search in the 

 eastern and northern states. The disease is now known to be 

 scattered (on currants at least) over New England with the 

 exception of northern New Hampshire and Maine. Serious in- 

 fections have been located in New York, Michigan, Minnesota 



1 See U. S. Department of Agriculture Farmers Bulletin No. 742, "The White- 

 pine Blister Rust," by Perley Spaulding. 



