B. P. I.-746. 



STUDIES OF FUNGOUS PARASITES BELONGING TO 

 THE GENUS GLOMERELLA. 



INTRODUCTION. 



The name Glomerella was first applied by Yon Schrenk and 

 Spaulding (70) * to the ascogenous form of the fungus producing the 

 bitter-rot of the apple and the ripe-rot of the grape, usually referred 

 to in its conidial condition as Gloeosporium or Colletotrichum. The 

 same fungus, or fungi belonging to the same genus, attacks a great 

 variety of other plants and produces diseases which are sometimes 

 called "anthracnose/' of which the anthracnose of the bean is a 

 familiar example. In current usage, the term " anthracnose " is 

 applied to diseases caused by fungi belonging to a few other genera 

 besides Glomerella. It would be better if the name "anthracnose" 

 were restricted to the disease caused by Glomerella. It still remains 

 to be determined, however, whether some of the so-called anthrac- 

 noses are caused by Glomerella or not, as the complete life histories 

 of the organisms are not all definitely known at present. 



This genus of fungi is of vast economic as well as scientific impor- 

 tance. Few fruits are free from its attacks, and it is known to occur 

 on a great variety of other hosts, from the palms to the highest flower- 

 ing plants. It is also cosmopolitan in its distribution, though most 

 abundant in temperate and tropical regions. 



All the facts connected with the life history of a parasite, the 

 causes of its variability, its behavior under different conditions, and 

 its relation to different hosts are essential to the most comprehensive 

 and successful development of practical methods for the prevention 

 and control of disease. 



The primary objects of this investigation have been to determine 

 the life histories and habits and the identity or relationship of the 

 forms of Gloeosporium and Colletotrichum found upon the same hosts 

 and on different hosts. Attention has also been given to the physio- 

 logical features of the fungi and the possibility of their passage from 

 one host to others. Careful studies of pure lines or races originating 

 from single ascospores and single conidia have been carried on 

 through many generations in order to determine, if possible, the 

 conditions affecting the production of the ascogenous stage and the 

 causes of the variations which sometimes appear in pure cultures. 



1 The numbers appearing in parentheses in this bulletin refer to the list of literature cited on pp. 101- 

 105. 



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