16 



MASS. EXPERIMENT STATION BULLETIN 368 



near the tip of the terminal shoots. In the tree inoculated from the twig culture 

 the discoloration extended 3 centimeters upward and 2 centimeters downward. 

 The fungus was reisolated from the streak. In the tree which had been inoculated 

 from the agar culture the streaking extended 2 centimeters upward and 2 cen- 

 timeters downward; the fungus was reisolated from this discoloration also. 



Neither of the English elms ( U. campestris L.) showed any external symptoms 

 of the disease. Only one tree, that which had been inoculated with the twig 

 culture, showed discoloration; in this the streak extended 4 centimeters upward 

 and 2 centimeters downward. The fungus was isolated from the tree showing 

 discoloration but not from the one which showed no discoloration. 



The specimens of Moline elm ( U. glabra L. var. fastigiata Rehd.) obtained 

 for the experiment were in very poor condition when received. Of the two inocu- 

 lated, one died shortly ater the inoculation; the other, which was inoculated from 

 the twig culture, was dead at the final inspection. It showed no extension of the 

 discoloration, but the fungus was reisolated from the point of inoculation after 

 a period of six months within the host. These results were not considered a 

 fair test of the susceptibility of this host and have not been considered in the 

 analysis of results from experimentally induced infections. 



Neither of the trees of U. parvifolia Jacq. exhibited any external symptoms of 

 the disease. There was no internal discoloration in the tree inoculated from the 

 agar medium, and tissue plantings from the point of inoculation did not yield 

 the fungus. The tree which had been inoculated from the twig culture showed 

 discoloration 3 centimeters upward and 1 centimeter downward; the fungus 

 was reisolated. 



The Siberian elms ( U. pumila L.) also showed no external symptoms. The 

 tree inoculated from the twig culture showed discoloration for 4 centimeters 

 upward and 7 centimeters downward; the tree infected from the spores in agar 

 medium showed streaking 2 centimeters upward and 3 centimeters downward. 

 The fungus was reisolated from both trees. 



The check trees showed no symptoms of the disease. 



Figure 10. American Kims wiiich died back after inoculation witli the causal fungus. Cephalo- 

 sporium sp. was reisolated from the pruned leaders. Photographs show new sprouts from below 

 the infected wood. 



