"WITCH'S BROOM" ON JAPANESE CHERRIES 



BY C. W. H. DOUGLASS 



WITCH'S Broom," a peculiar form of tree growth 

 which is caused by the attacks of a parasitic fun- 

 gus, has been recently discovered on Japanese 

 cherry trees presented to the United States by the Jap- 

 anese Government during President Taft's administration. 

 These trees were imported in a shipment containing many 

 varieties of Japanese flowering shrubs which are used for 

 ornamental purposes in Japan and were considered suitable 

 to our climate, and were set out in Potomac Park, part of 

 the beautiful park system of Washington, D. C. Despite 

 the facts that a previous shipment was destroyed because 

 of possible danger of introduction of diseases and insect 

 pests and that this second one was carefully examined both 

 before leaving Japan and after arriving here, the disease 

 came in undetected. What the result will be no one can 

 tell. It may spread to our native cherry trees and do an 

 enormous amount of damage and it may do little or no harm. 

 Importation of trees and plants is often fraught with 

 great danger. A plant that may not be harmful in its na- 



tive haunts may become a danger in new surroundings ; a 

 disease that may have lived for centuries on plants without 

 attracting attention because of the mildness of its activities 

 on the native hosts, may run like wildfire and do great dam- 

 age if allowed to spread and attack a new host. In both 

 cases the reason for the sudden activity is that the forces 

 which nature developed to prevent the dominance of any 

 one individual at the expense of others are lacking in the 

 new surroundings. 



It is recognized that plants gradually develop a resist- 

 ance to disease which may amount almost to immunity. 

 Thus down through the years the disease may be attacking 

 and the plant defending, with the result a deadlock. But 

 allow the disease to spread to another species of the plant, 

 one that has never been attacked and has therefore had no 

 occasion to develop resistance, and the results are likely to 

 be very destructive. Two widely-known examples can be 

 found in the chestnut and white pine forests of the Eastern 

 United States. Dead chestnuts and pines bear mute testi- 



GOVERNMENT CHERRY TREE DISEASED 



On the left is a Japanese flowering cherry tree, one of those presented to President Taft by the Japanese Government and planted in Potomac Park, 

 Washington, U. t,. rhis tree was removed as soon as it was found to be diseased. Out of a shipment of several thousand cherry trees about twenty were 

 subsequently found to be infected with a parasitic fungui which caused a short, dense growth generally known as "witch's broom." This particular tree was 

 probably attacked while a small seedling, as it is entirely " broomed." The normal tree on the right shows the contrast. 



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