22 



of part of the injury to the grain which results in its being classed 

 as of lower grade. 



The fungus causing this spot, C ercofifora coifeicola, has been re- 

 ported from Central and South America. Doubtless it occurs 

 throughout the American coffee-growing regions. In Porto Rico it 

 is present to some extent in every plantation. Both leaves and berries 

 are affected by the disease. On the leaves it causes round spots, 

 varying from 6 to 10 millimeters in diameter, of a brownish color 

 somewhat lighter toward the center than at the edge. There are 

 rarely many on any one leaf, and so little harm is done by the fungus 

 as a leaf parasite as to be negligible. On the leaves, however, they 

 produce spores which serve to spread the disease and to carry the 

 fungus over from one crop to another. On the berries the largest 

 spots, those fastening the fleshy part of the fruit to the parchment, 

 almost always are found on the upper side. Any part of the fruit 

 may be attacked, the spots appearing at first as small brown dis- 

 colorations. They are especially common on the nearly ripe berries. 

 At the time of picking, the larger spots cover about half of the fruit 

 and are velvety with the spore-bearing outgrowths of the fungus. 



The occurrence of the largest and worst spots on the upper or sun- 

 exposed side of the berries is to be explained by the fact that the spots 

 develop more rapidly in the somewhat riper tissue of that side, such 

 uneven ripening of the berry being caused by the direct exposure 

 each day to the sun rays. After the berries have become infected 

 this one-sided ripening takes place more rapidly, the berries being 

 black above with the Cercospora spot and still green on the underside. 

 Wliether picked at once or left until thoroughly ripe the berry is 

 difficult of preparation and yields a somewhat inferior product. 

 That the riper tissue furnishes more favorable conditions for the 

 fungus is indicated by the more rapid development of the spots pro- 

 duced by inoculation into ripe berries, and the greater number of 

 spots developing on the nearly ripe tissue. 



The uniformity with which the upper side of the berries is the part 

 most injured may account for the idea that such berries are injured 

 by hail. As a matter of fact hail is almost unknown at the eleva- 

 tions where the worst affected plantations are situated. Another and 

 better explanation quite commonly given is that the berries are 

 burned by sun either directly or intensified by the lens-like action of 

 drops of water, the disease itself being for this reason sometimes re- 

 ferred to as the " sancocho " of the berries. The presence of an or- 

 ganism, of proved parasitism, even in the earliest stages of the dis- 

 eased spots, makes these theories untenable. Sunlight is a factor of 

 importance, but only as it influences the development of the spots that 

 happen to occur on the upper side of the berries. These become con- 

 spicuous and are thought to be the only ones, the others remaining 



