DISEASES 157 



Coffee Leaf Disease 



(Hemileia vastatrix) 



This too familiar disease, when once seen, can- 

 not be mistaken for any other parasite on Coffee. 

 The leaf is the part most frequently attacked, the 

 fungus bursting through the skin under the form 

 of deep orange, powdery patches which are com- 

 posed of the spores, or reproductive bodies of the 

 fungus. The spores are of two kinds and serve 

 different purposes. The most numerous kind are 

 capable of germinating and infecting a plant the 

 moment they are mature, and it is owing to these 

 spores that the disease spreads so rapidly when it 

 has once gained a foothold. The second form of 

 spore, which grows mixed with the more numerous 

 kind, is known as a resting spore. It does not ger- 

 minate at once, but remains attached to the leaf, 

 which usually falls to the ground soon after the 

 mass of spores has been shed. The resting spores, 

 still attached to the fallen dead leaves, germinate 

 in course of time, and set up a fresh wave of dis- 

 ease. The young shoots and berries are also some- 



