PLANT DISEASES 



235 



Molds and mildews. The molds and mildews may be either 

 parasites or saprophytes. As parasites they cover the leaves 

 of many species with a cottony or powdery growth which is 



FIG. 173. Downy mildew on the grape 

 From Duggar's "Fungous Diseases of Plants" 



the plant body, or they push into the interior of the plant, 

 whence later their spores are released. The plants are often 

 called downy mildews, to distinguish them from other species. 

 One form of mildew is nearly always present on the lilac, and 



