1892.] PUBLIC DOCUMENT— No. 33. 231 



After a year or two of other than cruciferous crops (cab- 

 bages, turnips, radishes, etc.), the danger from the disease 

 is past, and the latter may again be planted for a year. 



The Blight of Celery^ which forms spots on the leaves, 

 is due to a parasitic fungus form which bears summer spores, 

 known as Cercospora Apii Fres. That this represents 

 merely an imperfect form of some fungus whose perfect 

 form probably lives saprophytically, cannot be doubted ; but 

 no other form has thus far been connected with it. I have 

 observed on celery, from the farms of Messrs. W. D. Phil- 

 brick of Newton Centre and A. H. Smith of West Spring- 

 field, that, after the brown blight spots have spread over 

 the leaves and they have collapsed upon the ground, there 

 appear upon them the tiny black pustules of one of the 

 pycnidial forms known as Septoria. From the analogy of 

 other cases and from the evidence of a series of specimens 

 in different stages of the disease Idndly sent by Mr. Smith, 

 it is easy to believe that the Septoria form represents an- 

 other stage in the history of the same ftingus to which the 

 Cercospora form belongs, although I have not been able to 

 make cultures. One would, however, expect little addi- 

 tional evidence except from cultures of the perfect spore- 

 form, which we do not yet know. 



Since there have already been described several so-called 

 species of Septoria on various umbelliferous plants which 

 differ in no essential particulars from this form and from 

 each other, it would be worse than superfluous to add here 

 another to the already large list of names which have been 

 given to what must eventually be shown to be a single form. 

 And especially so since this form is undoubtedly merely an 

 imperfect stage in the life cycle of some fungus for which, 

 when its whole course of development is known, only a single 

 name can stand ; while the host of names inconsiderately 

 given to its various imperfect forms will constitute only a 

 cumbrous and useless synonymy. So far as it has been 

 possible to examine material and descriptions, it appears that 

 this form on celery is separated by no distinct features from 

 the following previously described ones on Umbelliferae: 

 S. Sii Rob. & Desm., S. Cryptotaeniae E. & Eau, S. 

 Saniculae E. & E., S. Dearnessii'E. & E. and S. Petroselini 

 Desm. 



