328 DISEASES OF CULTIVATED PLANTS 



of the epidermis, subglobose, epispore hyaline, smooth, 

 contents rose-colour, 13-15 /* diam. 



Klebahn, Die Wirtswechselnden Rostpihe, p. 396 (1904). 



HEMILEIA (BERK. AND BROOME) 



Uredo stage forming powdery orange patches ; uredospores 

 in small heads or clusters, borne on hyphae emerging through 

 stomata, reniform or subglobose, the whole or only a portion 

 of the surface warted, germ-pores 3-5. 



Teleutospores springing from centre of cluster of uredo- 

 spores, after the latter are fully developed, i -celled, broadly 

 ovate, umbonate, germ-pore apical. 



Aecidium stage unknown. 



Characterised from other Uredineae by the mycelium 

 producing the uredospores and teleutospores, emerging 

 through the stomata only, and not pushing through the 

 epidermis. 



Coffee leaf disease. This dreaded disease is in all pro- 

 bability present wherever coffee is cultivated in the Old 

 World. Curiously enough it has not been recorded from the 

 New World, its place being taken by Sphaerostilbe flavida, 

 Mass. ( = Stilbum flavidum, Cooke). The leaves are most 

 frequently attacked, although the young shoots and berries do 

 not escape. On the leaves the earliest indication of the 

 disease is the presence of more or less circular, discoloured 

 spots. These increase in size for some time and become pale 

 yellow, and studded with bright yellow clusters of spores, 

 which soon assume a bright orange colour. The patches 

 show on both surfaces of the leaf, but the spore-clusters are 

 confined to the under surface. 



It is somewhat remarkable that no attempt has been made 

 to discover an aecidium condition. Should heteroecism be 

 proved to exist, the fact would be of value in any attempt to 

 check the progress of the disease. Two species, Hemileia 

 vastatrix (Berk, and Broome) and H. Woodii (Kalchbr. and 

 Cooke), are known as parasites on species of Co/ea, and as 

 these species are parasitic on several other rubiaceous plants 

 having a widely extended geographical range, their distribu- 

 tion should be carefully studied by those establishing coffee 

 plantations in a district where trees bearing the parasite are 

 present. 



