DISEASES OF COTTON 265 



yellow stained lint, variable in size owing to the decrease of 

 susceptibility and the shorter time available as the boll develops. 

 The staining is not superficial, as in the parallel case of bug 

 injury, but extends to the seed, nor is it confined to the lint of 

 one seed, but is indiscriminate. 



To this kind of infection a large part of the staining of seed- 

 cotton which has occurred in these islands has been due. Staining 

 indistinguishable in appearance is also caused by the ordinary 

 bacterial boll disease, the organism of which gains access to the 

 lint through the spots caused by external infection of the boll. 

 This disease is largely dependent on wet weather ; dry weather 

 staining, which has occurred abundantly towards the end of the 

 season, as well as a variable proportion of that which occurs in 

 wet weather, is the effect of the disease under description. 



The statement regarding staining which has been usually 

 repeated by entomologists, that it is due to the excrement voided 

 by Dysdercus and to the crushing of that insect in the gins, has 

 so far as the West Indies are concerned no basis whatever of 

 observation, experiment or probabihty The staining is present 

 days or weeks before the boll is due to open. 



The Parasites. 



A general description of the invading fungi is given in 

 Chapter I, pp. 29-32. Four species, evidently of general distribu- 

 tion through the islands, have been met with in cotton. Species 

 A, not yet named, has been predominant in cotton stainer 

 infestations in St. Vincent ; Species B {Eremoihecium cymhalarice, 

 Borzi) has been found most abundantly in bolls from Nevis and 

 Tortola, again in connection with stainers ; Species C has been 

 predominant in stainer infestations in Montserrat ; Species D, 

 which is Nematospora Coryli Peglion, or very near that species, 

 occurs in close association with the green bug, a fairly general 

 feeder, which presumably accounts for this fungus having been 

 found over much the widest range of hosts, and especially in 

 leguminous species, which the green bug prefers. 



The first three species are hyphal, the fourth, though it 

 produces hj^hse in starved cultures and sometimes in the cotton 

 boll, is normally yeast-like. All four develop freely on the im- 

 mature lint, and frequently enter and occupy for some distance 

 the lumen of a fibre. Spores are produced in great abundance 

 before the boll opens. Their after-history is unknown, but in 

 cultures they germinate freely. In what form the infection is 

 conveyed to other bolls has not yet been discovered, but bugs 

 taken from infected plants and bagged on previously protected 

 bolls almost invariably cause infection, while with bugs from 

 iminfected plants, though hundreds of punctures may be made, 

 no infection occurs, showing that the insect not merely provides 

 the means of entry but conveys the fungus from plant to plant. 



The bacterial form of disease has not been investigated suf- 



