140 MANUAL OF TREE DISEASES 



But little is known of the life history of this parasite. The 

 spores produced in the black dot-like fruiting-bodies on the 

 spots have been proved to infect other healthy chestnut leaves. 

 In this way the fungus is probably disseminated by the rain, 

 washing and spattering the spores. A perithecial stage of the 

 fungus is probably developed in the dead leaves on the ground 

 from which primary infection may be brought about in the 

 spring. This point is, however, undetermined. 



Control. 



Apparently no attempts have been made to control this 

 disease. General suggestions for the control of leaf-spot dis- 

 eases are given on page 33 and may be of some application to 

 this disease. 



Reperbnce 



Graves, A. H. The large leaf spot of chestnut and oak. Myeologia 

 4 : 170-174, pi. 69, fig. 1. 1912. 



Twig-Blight 



Caused by Spharopsis malorum Berkeley ( = Physalospora cydonite 



Arnaud) 



This twig-blight is more common and destructive on chestnut 

 oak. It occurs occasionally on chestnut in central eastern 

 United States. Cankers are formed on the small branches 

 and twigs. The leaves wilt and turn brown in midsummer. 

 A fuller description of this disease and its control will be found 

 under oak diseases, on page 244. 



Endothia Canker 



Caused by Endothia parasitica (Murr.) Ander. and Ander. 



All the species of the genus Castanea are susceptible to this 

 destructive fungus. The trees included in this group are: 

 the common American chestnut, the eastern chinquapin, the 



