PEACH DISEASES 



317 



of conidia are developed. From the mycelium erect stalks 

 are formed which bear conidia in chains at the tip. These 

 stalks are the conidiophores ; they, with their conidia, add to 

 the felt-like, whitish growth, covering the diseased portion. 

 The conidia are scattered throughout the summer, and those 

 which fall on peaches will, under favorable conditions, germinate 

 to start a new mildew spot. From the germtube a dense mat 

 of mycelium develops. At intervals over the hyphal system, 

 sucker-like bodies, called haustoria, are sent into the epidermal 



FIG. 84. Peach-mildew on fruits. 



cells. These haustoria are the feeding organs of the fungus, 

 and as a result of their activity the attacked portion becomes 

 brown and cracked. 



After midsummer perithecia may be developed. These 

 bodies when formed carry the fungus through the winter, but 

 as a rule they are extremely rare. When found they occur 

 more on twigs than on leaves. In those cases where perithecia 

 do not develop, it is thought that the fungus hibernates as 

 mycelium in the buds. 



The fungus thrives best in a warm, moist, shaded location. 

 Trees that are closely planted are more likely to be affected ; 



