288 LANDSCAPE GARDENING. 



it, but when the parasite has become fully established 

 nothing will destroy it that will not destroy the host plant. 

 The treatment is the same as for the rusts. 



MILDEWS OR WHITE RUSTS As the name indicates, 

 these are parasites which produce white spores and more or 

 less white patches on the leaf or other parts. As with the 

 two previously named groups, they grow under conditions 

 of moisture and hot, moist weather, and as a rule they 

 appear later in the season. 



Among the most destructive of this group are the ROSE- 

 MILDEW (Sphcvrollieca pannosa), POWDERY MILDEW OF 

 THE HAWTHORN, PLUM, AND CHERRY (PodospUcera oxy- 

 canthm), DOWNY MILDEW OF THE WILLOW (Uncinula 

 salicis), DOWNY MILDEW OF THE LILAC (Microsphcera 

 Alni D. (7.), etc. 



Remedy. Coming on later in the season than the brown 

 rusts, two or three applications of either the Bordeaux 

 mixture, dilute copper sulphate, or the ammoniacal car- 

 bonate of copper will be effectual, but no application 

 need be made generally until the middle or last of July. 



Flowers of sulphur if dusted over trees and shrubs will 

 often reduce the mildews, but not often wholly destroy 

 them. 



As with new insects, fungi new to any individual that 

 may appear to be doing serious harm may be sent to the 

 experiment stations for identification or for suggestions as 

 to the best remedies. 



