OMPHALIA FLAVIDA 401 



sooner than those not affected and, owing to the weakened condition 

 of the tree, are not soon replaced. After the first severe attack, 

 the base of each tree may be seen surrounded by a pile of green 

 leaves several inches deep. The disease never kills the trees. They 

 live on with scanty foliage and are able to put forth new growth 

 and bear a small amount of berries each year." 



The tiny yellow pin-like fruiting structures described by Fawcett 

 as projecting from the surface of the leaf-spots are the so-called 

 stilbum-hodies. A stilbum-hody never produces any spores ; but, 

 when fully formed, its head, often called a stilbum-head, is readily 

 detachable (c/. Figs. 205, A, p. 408, and 213, C, p. 424). " The 

 fungus," says Fawcett, " is distributed by the heads at the ends of 

 the filaments being caught by the wind or rain-drops and carried to 

 near-by leaves, a process facilitated by the heads becoming loosened 

 in the older filaments through the formation of cavities or ' lacunae ' 

 near the point of attachment. The head is soon fastened to the 

 leaf on which it happens to fall by the numerous threads which it 

 sends out at the point of contact. Within less than a week a dark 

 circular spot is formed and new filaments appear and new loosely 

 attached heads are formed on these by means of which the spread of 

 the disease is continued." 



Recently Briton- Jones ^ has attempted to control the Coffee-leaf 

 disease by heavy pruning followed by the removal of all the re- 

 maining leaves and by manuring and cultivation to induce the 

 subsequent production of vigorous new growth. 



Stilbum flavidum as a Stage in the Life-history of Omphalia 

 flavida. — In 1880, some diseased Coffee leaves were sent to M. C. 

 Cooke 2 from VenezAiela by Dr. Ernst. On some of the coloured 

 spots Cooke found the perithecia of Sphaerella cojfeicola ^ and on others 

 the tiny yellow Stilbum-like fruiting structures of another fungus 

 which he called Stilbum flavidum. In some of the spots the two 



1 H. R. Briton-Jones, " Control of the American Leaf Disease {Omphalia flavida) 

 on Arabian ColTee in Trinidad," Memoirs of the Imperial College of Tropical Agri- 

 culture, Trinidad, Mycological Series, No. 2, 1930, i^p. 1-8. 



2 M. C. Cooke, " The Coffee Disease in South America," Journ. Linn. Soc, 

 Botany, Vol. XVIII, 1881, pp. 461-467, PI. XVIII, Figs. 1, 5, 6. 



^ According to E. J. Butler (Note on Cooke's type specimens at Kevv, 1915) 

 Sphaerella coffeicola is a Didymella, for its perithecia contain paraphyses. 



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