228 DISEASES OF CROP-PLANTS 



Spraying is likely to have its greatest value when adopted 

 to preserve the freedom of young plantations from the disease. 

 Fawcett quotes an instance where the advent of the disease 

 in a plot of which the annual yield was known resulted in a 

 reduction of output of some 75 per cent. 



Brown Eye-spot 



A Cercospora spot disease of leaves and berries is common 

 throughout the Antilles, in Central and South America, and 

 has been reported from various situations in tropical Africa and 

 the East. It is the opposite of the disease last described in being 

 most abundant under conditions of exposure. 



Symptoms, 



The spots produced on the leaves are round, 6-10 mm. 

 {\-\ inch) in diameter, visible on both sides ; at first brown, 

 later becoming almost white in the centre, but retaining a reddish- 

 brown ring with a sharply defined outer margin. The central 

 part does not break away when dry, which serves as a rough 

 distinction from the previous disease. The leaf spots are pro- 

 duced somewhat scantily and are usually negligible in their 

 results. On the berries black blotches, which may cover as much 

 as half the surface, are produced, and are most fully developed 

 on the upper side where the sun causes earlier ripening. All 

 varieties of coffee are subject to attack. 



Causative Fungus. 



The cause of the disease is the fungus Cercospora coffeicola 

 Berk, et Cke., first described from Jamaica. It is visible on the 

 surface of the spots in the form of small greenish-olive tufts made 

 up of the simple conidiophores, on which are formed terminal 

 conidia. These are long and narrow, tapering to one end, 

 several-septate, colourless, with dimensions 75 X 3 microns at 

 the thicker end. 



Fawcett has obtained in cultures a grey sterile mycelium 

 which produced spots with the typical spores on inoculation. 



Losses. 



The affection on the berry causes trouble in the preparation 

 of the produce owing to the adhesion of the flesh to the parchment 

 of the bean. It is also believed to be connected to some extent 

 with the poor development of some of the beans met with in the 

 crop. 



Incidence and Control. 



Although the disease is not entirely dependent on poor 

 condition in the trees it is most prevalent where shade is in- 



