THE FUNGI WHICH CAUSE PLANT DISEASE 539 



Gloeosporium and Colletotrichum are prominent in pathology as 

 the " anthracnose fungi" and cause many important diseases. The 

 two genera, separated only by the occurrence or non-occurrence of 

 setae, contain many species which have been transferred from one 

 of these genera to the other on this character, which is to some ex- 

 tent a variable one depending upon the supporting medium, con- 

 ditions of growth and the particular strain of the fungus under 

 observation. 



Many form-species have been described solely on a basis of 

 the hosts affected. Subsequent culture study, and cross inocula- 

 tion has often failed to sustain these species so that many forms 

 that were formerly considered as distinct are now grouped under 

 one name. No satisfactory disposition of these forms can be made 

 imtil their ascigerous stages are known and compared and their 

 biologic relations investigated. 



Such work as has been done (see page 267) leads rather to con- 

 solidation than to segregation of species. 



For sake of clearness and convenience, mention is made below 

 of many form species of these two genera under their old names, 

 though the evidence now is that in many instances they should be 

 consolidated with other species. 



Gloeosporium Desmazieres & Montaigne (p. 538) 



Conidial layer subepidermal, disciform or pulvinate, usually 

 erumpent, pale or fuscous; conidia ovate, rarely oblong; conidio- 

 phores needle-shaped. 



In part=Glomerella, Pseudopeziza, Gnomoniella, Gnomonia, 

 Trochila, Physalospora, Calospora. 



There are over three hundred species of parasites, many of 

 them very important pathogens. The spores in germination 

 commonly form dark colored, thick-walled chlamydospores and 

 usually become 1 -septate. 



G. rufomaculans (Berk.) Thiim. on a large variety of hosts= 

 Glomerella rufomaculans. See p. 264. 



G. melengonea E. & H. is reported on egg-plant fruits in New 

 Jersey;^* G. orbiculare Berk, on cucurbs; 



G. fructigenum Berk, on many fruits. 



G. laeticolor Berk, on peaches and apples and G. versicolor 



