New York Agricultural Experiment Station. 533 



ExoascxLS Gerasi. Although the English cherry, P. Avium, is 

 commonly cultivated in the eastern United States, and has been 

 thoroughly naturalized, the disease was not observed upon it here 

 until Mr, Thomas Meehan reported it from Germantown, Pennsyl- 

 vania, in 1886. The specimens which he collected were distributed 

 in "North American Fungi," 'No. 2286, under the name Exoascus 

 Wiesneri. So far as I can learn it has been found upon the culti- 

 vated cherry in no other locality in America until I found it this 

 spring on Long Island, in five different places, namely ; Queens, 

 Westbury, Floral Park, Cutchogue and Flatbush. It appears to be 

 widespread on Long Island. 



The disease manifests itself by causing the leaves to become red- 

 dish and wrinkled before they attain fall size. By May 23 the 

 under surfaces of the leaves are covered by a white, mealy layer 

 which is composed of the spore sacs (asci) of the fungus. Dr. Rob- 

 inson says 3 that the asci occur on both sm-faces, but Prof. Atkinson 

 found them only on the under surface in the Germantown speci- 

 mens. I have examined a large quantity of the Long Island 

 material, and in no case have I found asci on the upper surface. 

 After the white layer makes its appearance the leaves dry up and 

 fall off in a few days. Later, new leaves come out. The affected 

 branches produce no flowers. Where flower-buds should be found 

 twigs appear instead, and the repetition of this process brings about 

 the "broom." 



Probably the scarcity of the .disease in America is due to our cli- 

 mate being unfavorable to it. Mr. Meehan states that it does not 

 seem to spread. This is strange, because, according to Mrs. F. W. 

 Patterson,^ the same fungus occurs in America on Prunus serotinay 

 P. Amei'icana, P. Virginiana, P. deTuissa, P. hortulana and P. 

 Pennsylvanica. The form on P. serotiria is common, and why 

 should it not thrive on P. Avium f 



In case the disease should show a tendency to become trouble- 

 some, it could probably be controlled by cutting out and destroying 

 the " brooms " before the spores come to maturity. This can easily 

 be done, the diseased twigs being indicated by the red color at least 

 a week before the spores mature. 



It should be remembered that the fungus is perennial in the 

 twigs, hence the disease may be transmitted by grafts. 



3 Notes on the genus Taphriiia, Ann. Bot. I, p. 169. 



4 A Study of North American Parasitic Exoasceae. Bull. Lab. Nat. Hist. State University of 

 Iowa, Vol. m, No. 3, p. 1-21. 



