;v 



m^A 



SOIME OBSERVATIONS ON WITCHES BROOMS OF 



CHERRIES 



HENRY SCHMITZ 



University of Washington, Seattle, Washiicglon 



The purpose of the present note is to record certain interesting 

 facts that arose in connection with a microchemical study of 

 ''witches brooms" of cultivated cherries. It is well known, of 

 course, that these brooms are caused by a certain filamentous 

 fungus, Exoascus cerasi (Fcl.) Sad. It was also desired to ob- 

 tain some additional information in regard to the metabolism of 

 the infected area and to determine, if possible, the cause of the 

 decided red coloration of the leaves of the brooms, especially in 

 their younger stages. 



The opinion is still held by some workers that manj^ hyper- 

 trophies such as witches brooms do not carry on photosynthetic 

 processes to an^- appreciable extent. That is to say that the 

 increased growth results practically entirely at the expense of 

 the remainder of the tree. That this is not the case, but on the 

 other hand that there is active assimilation carried on in the 

 broomed portion, has been conclusively demonstrated by Hein- 

 richer^ in a series of simple but interesting experiments. 



It is evident to any one who has observed cherry brooms that 

 the leaf buds of the brooms unfold some considerable time before 

 the buds of the normal parts. The almost entire absence of 

 flowers on the broomed area is also plainly evident. The rest- 

 ing winter condition of the broom has been investigated by 

 Schellenberg.- By taking portions of the broom and the nor- 

 mal twigs at different times of the winter and placing them in 



' Heinricher, E., Berichte tier Deutschen Botanischen Gesellschaft. Band 

 XXXIII, Heft 5, 1915. 



- Schellenberg, H. C, Berichte tier Deutschen Botanischen Gesellschaft. 

 Band XXXIII, Heft 2, 1915. 



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