THE COFFEE-DISEASE IN SOUTH AMERICA. 461 



Probably this pitting may have had something to do with the safety 

 of the Coorg trees; but it seems strange the Ceylon plants 

 should get it, as soil, exposure, and cultivation were the same in 

 every way. 



J " Wm. Bidie." 



The Coffee-Disease in South America. 

 By M. C. Cooke, M.A., A.L.S. 



[Read February 3, 1881.] 

 (Plate XVIII.) 



The coffee-plant seems destined to become the victim of destruc- 

 tive parasites in all countries wherever it is extensively culti- 

 vated. The Ceylon coffee-disease has long been known ; and its 

 fungus, the Hemileia vastatrix, has had considerable attention 

 and been made the subject of successive investigations. Pro- 

 bably we are now in a fair way of knowing all that can be 

 known of its life-history ; and this is the only safe basis on which 

 to hope for a radical cure. 



The same pest is known in the coffee-plantations of Mysore, 

 accompanied by another form of disease known as the Kole- 

 roga, or black rot, also of fungoid origin, and apparently unknown 

 in Ceylon. It was this disease which I examined and reported 

 upon to the Government of India in 1876 under the name of 

 Pellicularia Koleroya *. The fungus is entirely superficial, spread- 

 ing over the leaves in a compact filamentous film, somewhat 

 like the mycelium of an Erysiphe in external appearance, but 

 quite different in its internal structure when seen under the 

 microscope. The felted threads bear their own proper spores, 

 reminding one somewhat of the genus Zygodesmus ; but the film 

 is so superficial that when it is moistened it can be removed 

 in flakes from the surface of the leaves without resistance. With 

 the majority, probably all, of the species of Erysiphe and its allies 

 the mycelium cannot be thus removed, on account of the processes 

 which enter the substance of the leaves through the stomata. 

 Until recently it was not known that this disease had made its 

 appearance on the coffee-plant outside of Southern India. 



The existence of destructive parasites on coffee in South America 

 was intimated as long ago as 1876, the same year in which the 

 * 'Qrevillea,' iv. p. 116. 



