DISEASES OF COTTON 277 



Anthracnose. 



The most destructive boll rot occurring in the United States 

 cotton belt is agreed to be the anthracnose produced by Glomerella «• 

 {Golletotrichum) gossypii (Southw.) which on occasion may destroy 

 50 per cent, or more of the crop in some localities. 



Occurrence in the Lesser Antilles, 



A disease which in general appearance closely resembles 

 anthracnose was noticed in the West Indies soon after the re- 

 vival of the Sea Island industry. Bolls from Barbados submitted 

 to W. A. Orton were found to bear a fungus which agreed with 

 the characters of the American species, except for the smaller 

 size of the conidia. This was described by L. Lewton Brain 

 as 0. gossypii, var. Barbadense, and it has been generally accepted 

 that boll rot due to anthracnose existed to an extent sometimes 

 serious in all the cotton-growing islands. It was regarded as 

 particularly destructive in St. Vincent, where practically the 

 whole of the heavy losses occurring in the wet periods to which 

 that island is subject were attributed to anthracnose. Investi- 

 gations made by the writer in St. Vincent on various occasions 

 since 1915, and the maintenance of constant observation on boll 

 diseases there by S. C. Harland, have shown that at least a very 

 large part of the loss is due to internal boll disease, Phytophthora 

 rot, and bacterial boll disease. Lesions closely resembling the 

 anthracnose of American writers and infested with a similar 

 pink-spored Golletotrichum or with a pink Fusarium are fairly 

 common, but in all the examples seen by the writer they appear 

 to develop on the spots initiated by Bacterium malvacearuni. 

 The status of Golletotrichum gossypii on Sea Island cotton in these 

 islands is therefore at the present time a matter of doubt, and re- 

 quires to be completely re-investigated. The description which 

 follows refers to the American type of disease. 



Symptoms. 



The fungus attacks the boll, according to the account given by 

 C. W, Edgerton, through the pistil from conidia reaching the 

 flowers, by penetrating the uninjured epidermis of young tender 

 bolls, and by way of insect punctures or bacterial spots on older 

 bolls. Beginning with a small spot the lesion extends to a vari- 

 able extent and may cover half the boll. The affected patch 

 is sunken and brovmish, with usually a red border. 



The lint and seed are affected to an extent varying from 

 slight damage to complete destruction, depending on the age of 

 the boll and also on the previous or concurrent presence of other 

 organisms. 



