THE DUTCH ELM DISEASE 



Fig, 



1. Elms in a Massachusetts 

 town. 



The Dutch Elm Disease — caused 

 by the fungus, Ceratostomella iilini, 

 and spread by bark beetles — 

 menaces our Massachusetts elms. 



Widespread in Europe since its 

 discovery in 1919. 



Known in the United States 

 since 1930, following the importa- 

 tion of fungus and carrier-beetle 

 infested elm logs from Europe — 

 1929 to 1934. 



Found in N. J., N. Y., Conn., 

 Pa., Md., Va., W. Va., Ind., Ohio, 



MASSACHUSETTS — 1941. 



Fig. 2. The street in figure 1, as it 

 would appear without elms. 



64,468 known diseased elms have been destroyed 

 programs to September 1942. 



in eradication 



Fig. 3. Elm affected with 

 Dutch Elm Disease. 



Fig. 4. Streaking of infected wood. 



Fig. 5. The fungus in culture. 



Fig. 6. A. Smaller European bark 

 beetle. 



B. Native bark beetle. 



C. Larva or grub. 

 (All great'.y en'areed.) 



Fig. 7. Work of carrier beetles. 

 (Somewhat rediced.) 



Fig. 8. Natural graft of elm roots. 

 (Photographs from Mass. Exp. hta. 

 Bui. 343. Figs. 3 and 8 furnished by 

 Division of Forest Pathology. 

 U S D A. Fig. 6 from Cornell 

 Ext.' Bui. 290.) 



Symptoms of the disease include: 

 Wilting, curling, yellowing, and 

 early falling of leaves; Brown 

 streaking of infected wood. 



Trees may die suddenly or grad- 

 ually. 



A wood-staining fungus living in 

 the water-conducting channels 

 causes the disease. 



Death of trees results from a 

 toxin produced by the fungus. 



Trees affected with Dutch Elm* 

 Disease may appear similar to 

 elms affected with other wilt 

 diseases — 



Therefore, laboratory study of 

 wood showing streaking is 

 necessary to prove which dis- 

 ease fungus is present. 



The smaller European and native 

 elm bark beetles serve as car- 

 riers of the fungus. 



The beetles engrave breeding 

 galleries in weakened trees and 

 later the young emerge to feed 

 on tender green twigs. 



Other means of spread include 

 direct contact between diseased 

 and healthy trees — natural 

 grafts of roots and branches. 



All known diseased elms are 

 being destroyed. 



The final goal of the eradication 

 program is the protection and 

 preservation of disease-free elms. 



The public is urged to cooperate 

 by sending specimens from the 

 wilted parts of trees to — 



THE DUTCH ELM DISEASE LABORATORY 

 MASSACHUSETTS STATE COLLEGE, AMHERST. MASS. 



