FOREST FUNGI 87 



forest products. The latter phases of the subject are actively carried 

 on at Madison, Wisconsin, in connection with the U. S. Forest 

 Products Laboratory. The Division of Forest Pathology also main- 

 tains branch offices at San Francisco, California; New Haven, Con- 

 necticut; New Orleans, Louisiana; Albuquerque, New Mexico; Woos- 

 ter, Ohio; Portland, Oregon; Philadelphia, Pennsylvania; and at 

 Edinburgh, Scotland. 



5. The Dutch elm disease or Graphium disease of elm is caused by 

 a recently introduced fungus. It was first discovered in America in 

 Ohio during 1930 and since that time has been found on elms in 

 New York, New Jersey, Connecticut, Maryland, and Indiana. It is 

 caused by a fungus which lives in the sapwood of the elm tree. It 

 constitutes a most serious menace to all native elms and was probably 

 introduced into this country from Europe on elm logs along with 

 elm bark beetles which are instrumental in disseminating the fungus. 

 The disease is evident largely through the wilting and death of the 

 leaves which may occur gradually or quickly, depending upon the 

 severity of the infection. After the leaves have wilted and dropped, 

 the bark begins to dry and crack. A brown discoloration occurs in the 

 sapwood. A federal laboratory has been established at Morristown, 

 New Jersey, known as the Dutch Elm Disease Laboratory, where 

 diagnosis is made of diseased twigs or those suspected of infection. 

 Several thousand elm trees have been found with Dutch elm disease in 

 the three states Connecticut, New Jersey, and New York. All trees 

 known to be affected with this disease in New York are removed 

 and destroyed. 



6. A recently discovered disease of beech now threatens to destroy 

 the beech forests of northeastern L^nited States. The disease is a bark 

 injury caused by a fungus known as Nectria. It eventually causes 

 the death of the affected trees. 



Many other varieties of fungi attack living, dying, or dead trees 

 and various forms of forest products. The life history of each kind 

 must be carefully studied and understood before adequate measures 

 may be recommended and adopted to combat it. Years of research 

 are sometimes necessary, as in the case of the white pine blister rust. 

 Many of these diseases have been introduced from foreign countries 

 where they may be of less serious nature. A plant quarantine service 

 has been established to examine carefully doubtful forms brought to 

 this country from abroad and to exclude undesirable or dangerous 

 ones. 



The rate of decay of lopped tops and other slash left after logging 

 operations has a very important bearing upon the fire hazards on the 



