166 DISEASES OF TROPICAL PLANTS CH. 



eyed disease on account of the brown spots formed on the 

 leaves. As a rule these are round or oval, on the lower surface 

 clear brown, on the upper surface dark brown. In the centre 

 the spots are lighter in colour and greyish. The margin is 

 sharply defined on the upper surface, dark brown or reddish, 

 generally slightly raised, the surface often marked by fine 

 concentric striae. Frequently several spots unite. The nerves 

 of the leaves do not prevent their spreading. The average 

 diameter of the spots at the centre of the leaf is one-fifth 

 of an inch. The largest are about one-third of an inch. If 

 a leaf is badly affected it appears more or less brown. The 

 formation of the spots begins on the upper surface of the leaves. 

 -The spots are at first without a sharp marginal line and are 

 scarcely visible on the under surface. The fungus not only 

 occurs on the leaves, but on the half-formed cherry little dark 

 spots appear which multiply and spread until finally about 

 half the cherry becomes brown and dried. 



There are other leaf-spot fungi which cause more or 

 less trouble in different localities. In most cases these 

 diseases are not of sufficient importance to cause serious 

 loss, and so attract little or no attention. Among the 

 most important is Colletotriclium coffeanum, Noack. 

 It has been reported from Porto Rico, but apparently does 

 very little damage. Gloeosporium coffeanum, Delacroix, 

 has been reported from Reunion and Madagascar. 

 Anthostomella cqffeae, Delacroix, Hendersonia cqffeae, 

 Delacroix, and Rhabdospora coffeae, Delacroix, have 

 been reported from Mexico. 



Leaf Rot or Black Rot. This disease was first 

 reported from India but is now prevalent in Jamaica, 

 Trinidad, Venezuela, and Porto Rico. It is due to a 

 fungus, Pellicularia koleroga, 1 Cooke, which grows on 

 the surface of the stems, leaves, and berries, but does 

 not penetrate. At first it appears as a smooth, thin, 

 whitish film which spreads, finally covering the new 

 parts with a slimy, gelatinous substance, causing the 

 leaves and berries to turn black, rot, and fall. The 

 berries frequently fall in clusters. No remedy has been 



1 Cooke says that Erysiphe scandens of Venezuela is the same as P. koleroga. 

 The same or a very similar disease in Venezuela is known by the common name 

 of "Candelillo." 



