19,6 Welles: Cercospora Leaf Spot of Coffee 743 
that this species is not parasitized by Cercospora coffeicola 
Berkeley and Cooke in the college nursery. 
Coffea bukobensis, the only diseased species, was obtained 
from the Kaiserliches Biologisch Landwirtschaftliches Institut, 
Hafen Taya, in 1914. It is, however, hard to believe that the 
fungus has been here for so long a period unnoticed. 
SYMPTOMS 
Up to the present time the fungus has been found to attack 
only seedlings in the nursery ; hence the berry spot, so destruc- 
tive in Porto Rico,(i) is not known. 
The lesions when young are light brown. Later the center 
portion turns grayish, exhibiting concentric striations and encir- 
cled by brown rings. The lesions are found mostly on the upper 
surface of the leaves. At first they do not penetrate through 
the leaf, but later a distinct spot is produced on the under 
surface. 
In some instances the spots coalesce and form an irregular 
lesion. In severe attacks the leaves turn brown and fall off, 
frequently leaving but a tuft of young leaves on a long stem. 
CAUSAL ORGANISM 
The organism which causes this leaf spot is Cercospora 
coffeicola Berkeley and Cooke. 
The typical Cercospora conidiophores and conidia are pro- 
duced in the grayish central portion of the lesions. 
The conidiophores occur in bunches which are formed in 
stomatal openings. They measure from 60 to 150 ju long and 4 
to 6 /x wide and are 5- to 10-septate. 
The conidia are from 70 to 130 n long and 5 to 7 ^ wide with 
from 5 to 12 septa. 
Butler (l) reports the formation of secondary conidia on the 
germination of the primary conidia, but these have not been 
observed here. The conidia germinate by means of long, slen- 
der, germ tubes. Several may arise from one conidium. 
CONTROL 
Spraying experiments carried on with Bordeaux mixture 
prove conclusively that the brown eye spot may be easily con- 
trolled. 
Spraying every two weeks is recommended. If the attack 
is limited in extent there is no reason why complete eradication 
may not be effected. 
