Ornamental Plants 



431 



the leaf dies. They also become more regular in outline than 

 in their earlier stages. Portions of the leaflets outside of the 

 area actually spotted often turn yellow, and the diseased 

 leaflets fall off prematurely. Thus the beds beneath diseased 

 plants are often strewn with fallen leaves. 



All infective material should be gathered and burned, and 

 by use of a good dormant spray both bushes and ground be 



Fig. 220. — Rose mildew; diseased and healthy shoots. 



well cleared of superficial spores. Ammoniacal copper car- 

 bonate used once each week is effective after the plants are in 

 foliage. Lime-sulfur or Bordeaux mixture may be used 

 when the residue on the foliage is not objectionable. 



Powdery-mildew {Sphceroiheca pannosa (Wallr.) Lev. or 

 S. humili (DC.) Burr, Oidium.). — This is perhaps the most 

 wide-spread and destructive of all rose diseases both under 

 glass and in the open, being especially destructive to the 



