162 DISEASES OF TROPICAL PLANTS CH . 



ably satisfied that it does not exist in the Western 

 Hemisphere, but that it has been confused with the 

 disease which will be considered next. This fungus 

 also grows upon many other plants, but has not been 

 reported on the wild Coffea arabica or C. liberica in 

 their native habitat, and it is therefore supposed to 

 have originated on some jungle plant not native to the 

 original home of the coffee and passed to the coffee 

 upon its introduction into the home of fungus. 



The Gardeners' Chronicle (6th March 1909, p. 153) 

 says : 



A new species discovered growing wild on the shores of the 

 Oubanghi, Central Africa, by Mr. Dyboneski, and named C. 

 congensis, which has been grown since 1903 in the botanical 

 garden at Ivoloina, has so far remained free from disease 

 (Hemileia'). Its market value is said to be fully equal to that 

 of the best qualities of Arabian coffee. While the present crop 

 of C. congensis has not suffered from the disease, C. arabica, 

 planted at the same time, has been entirely destroyed. 



Mancha de Hierro or Viruela. This is sometimes 

 called the American coffee disease, and is due to the 

 fungus Sphaerostilbe flavida, 1 Massee. Mancha de 

 Hierro is a name referring to the rusty iron colour of 

 the spots which the fungus produces on the leaves, and 

 "viruela" means " small-pox," arid is suggestive of the 

 appearance of the disease on the leaves of the plants. 

 It is, without doubt, the most severe disease of the 

 coffees in the Western Hemisphere, and rivals the 

 Hemileia vastatrix of the old world for which it has 

 sometimes been mistaken. 



It appears on the leaves as scattered circular whitish 

 spots, equally prominent on both surfaces, and about 

 J inch in diameter. The leaves soon turn yellow and 

 fall, and sometimes the attack is so severe that the 

 trees are defoliated within a month. In fact, the trees 

 are often seen loaded with fruit but entirely defoliated. 



On the young shoots the spots are whitish and 

 usually elongated. They become dry, crack, and the 



1 Syn. Pistillina flavida, Speg. 



