THE PERFECT STAGE OF THE COTTON 

 ANTHRACNOSE 



C. W. Edgerton 

 (With Plate 8, Containing Five Figures) 



Perithecia of the genus Glomerella, the perfect stage of cer- 

 tain species of Gloeosporium and Collet otrichum, have been de- 

 veloped in most cases under artificial conditions, either in pure 

 culture on artificial media or on old dead pieces of the host 

 plant that have been kept in a moist condition. In only a few 

 cases has the ascigeral stage been found developing naturally. 

 The form from apple has been reported as occurring naturally, 

 but even here the best development has been observed on arti- 

 ficial media or on diseased apples kept in a moist chamber. 



While making a study of the cotton anthracnose, Colleto- 

 trichum Gossypii, in Louisiana during 1908, search was made 

 at various times to discover whether the perithecial stage of 

 this developed naturally on the cotton plant. Shear and Wood* 

 have reported finding the perithecia in pure cultures, but their 

 presence on the living cotton plant, or even on old dead parts 

 of the plant, has never been reported. The anthracnose appears 

 on all parts of the plant, cotyledons, leaves, stems and bolls, 

 and search was made on all of these for the perfect stage. The 

 conidial stage was especially abundant, and it is doubtful whether 

 there was a single cotton plant in this section of the cotton belt 

 that was not more or less affected with this stage, and, during 

 the early part of the season, this stage alone was found. 



However, on August 1, after a period of very warm and very 

 wet weather, a single boll, picked while passing through a field 

 at Baton Rouge, was examined in the laboratory and found to 

 be covered with the perfect stage of the Colletotrichum. The 

 boll was living, only about one half of it being covered with the 



* Shear, C. L., and Wood, Anna K. Ascogenous Forms of Gloeosporium 

 and Colletotrichum. Botanical Gazette 43: 259-266. 1907. 



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