376 



Bulletin 604. 



again immediately, it seems. One of two possibilities is then 

 open ; either (i) to germinate immediately and infect the buds 

 which will open the next season ; or (2) to be hidden away about 

 the twigs, in the bud scales, or even on the ground about the 

 tree, and there to pass the winter, germinating the next spring. 

 On leaf surfaces of its host plant Sadebeck* has germinated the 



67. — Cross section of a part of a leaf affected with leaf -curl, showing 

 the fruiting of the fungus. {From Bulletin /j, by Professor 

 Geo. F. Atkinson. 



spores of a closely related species growing on Alnus. This took 

 place, apparently, soon after the spores were produced. It is hoped 

 that some studies now under way will throw light upon this 

 important matter, — important because treatment can be made 

 more effective the more complete is our knowledge concerning 

 time and method of infection. At present, the results from pre- 

 ventive treatments indicate that normal infections take place in 

 the spring. 



d. Conditions Affecthig the Abundaiice of the Leaf -Curl. 

 The sporadic occurrence of the leaf-curl is rather remarkable. 

 In many sections of the State there was very little in 1896. The 



* Unters. iiber d. Pilzgattung Exoascus, u. d. durch dieselbe um Hamburg 

 hervorgerufen Baumkrankheiten. Abgedruck a. d. Jahrb. d. Wiss. Anst. 

 p. 102, 1883, Hamburg. 



