298 DISEASES OF CROP-PLANTS 



some places began to return large quantities of " rotten cane," 

 and the epidemic of disease of which this was the first sign 

 developed with great suddenness and intensity throughout the 

 islands. 



Losses variously estimated at 25 to 50 per cent, are reported 

 from Trinidad, Grenada, St. Vincent, Barbados, Antigua and St. 

 Kitts in the years from 1892 to 1894. The disease is reported 

 to have appeared in British Guiana in the latter year and sub- 

 sequently to have made rapid progress in the colony. 



The diseased canes showed infestation with a " shot-borer " 

 beetle {Xyleborus perforans) and the affection was at first attri- 

 buted to this agency. Material was sent for examination to the 

 Royal Gardens, Kew, and from the examination of this and on 

 the strength of cultures and inoculation experiments made at 

 Kew, G. Massee, in 1893, reported that the " vexed question " 

 of the nature of the disease had been " conclusively settled," and 

 that it was caused by a fungus named by him Trichosphcsria 

 Sacchari, which formed perithecia on dead canes and had as 

 active conidial stages a Melanconium form {M. Sacchari, Mass.), 

 and a form producing micro and macro-conidia (the Thielaviopsis 

 ethaceticus of Went). Later he added as probably another form 

 of the same fungus Colhtotrichum falcatum Went, to which, from 

 its presence in certain stools examined, he attributed root disease 

 in Barbados. From the general occurrence on the surface of the 

 shrivelling canes of the acervuli and conspicuous sooty conidia of 

 Melanconium Sacchari the affection was commonly known as 

 rind disease. 



Later research has produced no support of Massee's pro- 

 nouncements : Trichosphaeria does not seem to have been met 

 with again, and Melanconium, Thielaviopsis, and Colletotrichum 

 are now recognised to be entirely separate fungi, each of which, 

 under certain conditions, produces a distinct affection of siiear- 

 cane, while root disease is attributed to Marasmiiis spp. 



A. Howard, working in Barbados, sorted out the confusion, 

 bringing the situation into line with Went's researches in Java, 

 and in 1903 brought forward evidence to show that the epidemic 

 was primarily due to the somewhat obscure infestation of the 

 canes with Colletotrichwn falcatum, a conclusion which all later 

 experience goes to confirm. 



The situation was met by the adoption of resistant varieties, 

 of which White Transparent, Caledonian Queen, and some others 

 were then available, and these have been followed by a succession 

 of seedling varieties mainly raised in Barbados and BrH"^sh 

 Guiana. The shot-borer still occurs in damaged cane, Me.jn- 

 coniiim Sacchari is everywhere abundant on over-ripe or injured 

 stalks, and Thielaviopsis causes losses of cuttings in dry planting 

 seasons. Colletotrichum on the other hand has become rare 

 except when an attempt is made to re-establish the Bourbon, 

 when the symptoms of the original trouble usually reassert 



