11 



reappearance of the disease and resprayed when found necessary. 

 Picking the leaves before the spraying will probably be of some 

 assistance if care is taken to remove as carefully as possible all the 

 threads on the twigs, using for the purpose the cheaper labor some- 

 times available for picking the berries. 



LEAF SPOT {SUlieUa flavida). 



This disease does not seem to be known in Porto Eico by any 

 definite common name, being merely referred to as a spotting of the 

 leaves. In Venezuela and apparently elsewhere on the continent 

 and Central America it is called " mancha de hierro," but no doubt 

 this term is made to include other small spots of both fungus and 

 insect origin. It is quite generally distributed throughout the coffee- 

 growing region of America, having been reported from Mexico, the 

 Antilles, and Brazil. In Porto Rico it is found principally in the 

 higher altitudes, where it is favored by excessive rainfall. Lower 

 down it is found near streams and where it is sheltered from winds 

 and afforded a moist atmosphere during part of the year. It is more 

 dependent on moisture than other coffee fungi, being unable to infect 

 new leaves or to form new fruits except under conditions of extreme 

 humidity. 



The disease is characterized by the occurrence on the leaves of 

 small spots usually circular in outline, but sometimes ovoid along 

 the veins. (PL II.) The newer ones are very dark, the older ones 

 light colored. The spots are usually about 6 millimeters in diame- 

 ter, although many of the older ones become 12 to 13 millimeters in 

 diameter. Sometimes they fuse or give entrance to other tissue- 

 destroying fungi which infect the intervening tissue, producing spots 

 of considerable size. The worst affected leaves have from 30 to 40 

 or even more spots, so that a large proportion of the leaf tissue is 

 destroyed. On the upper surface of many of the spots and also to 

 some extent on the lower surface may be seen hair-like projections 

 from 1 to 1: millimeters long of a yellowish color, each bearing at the 

 end a head so that they resemble minute pins. This is the reproduc- 

 tive or fruiting stage of the fungus. (PI. VII, A and B.) Each 

 spot produces a continuous crop of these hairs so long as weather 

 conditions are favorable. The total number at any time is small 

 and in an entire season but from 20 to 50 are produced in each spot, 

 judging from the number of old filament bases. The largest number 

 observed was 70 in a spot of 7 millimeters diameter. As the leaf 

 spots become older, growth having stopped for any reason, such as 

 the advent of the dry season, the diseased tissue falls away, leaving 

 numerous circular openings in the leaf. In other leaf diseases the 

 dead tissue remains. 



