PARASITIC FUNGI 89 



nated by distinct marks or spots upon the leaves 

 or stems, and the gradual weakening or death of 

 the part ; and, in many cases, the leaves drop 

 bodily. For the most part, these spots upon the 

 leaves or stems develop sooner or later a mildew- 

 like or rusty appearance, which is due to the de- 

 velopment of the spores or fruiting bodies. Fig. 

 89 illustrates the ravages of one of the parasitic 



89. Work of shot-hole fungus of plum. 



fungi, the shot -hole fungus of the plum. Each 

 spot upon the leaf probably represents a distinct 

 attack of the fungus, and in this particular dis- 

 ease these injured parts of tissue are liable to fall 

 out, leaving holes in the leaf. Plum leaves which 

 are attacked early in the season by this disease 

 usually drop prematurely ; but sometimes the 

 leaves persist, being riddled by holes at the close 

 of the season. Fig. 90 is the rust of the holly- 



