168 DISEASES OF ECONOMIC PLANTS 



HYDRANGEA 



Phyllostictose (Phyllostida Hydrangea Ell. & Ev.)- — 

 Large rusty brown blotches occur upon the leaves, in 

 some cases to such extent that the tops of the plants must 

 be cut away, to the entire destruction of their decorative 

 value. 



Cercosporose (Cercospora sp.). — Small, round or angular 

 white spots with a very small amount of dark hyphal 

 growth in the centers are common upon this plant. The 

 spots are definite and are bordered by a narrow reddish 

 purple hne. 



IVY (Hedera) 



Venniculariose (Vermicularia trichella Ft.). — This blight 

 usually begins midway between base and apex of the 

 leaf, and is especially conmion upon the white portions of 

 the variegated varieties. The diseased portions turn black, 

 and small black acervuli appear. 



LILAC 



Powdery mildew (M icrosphcera alni Wallr.). — The char- 

 acteristic spots of the powdery mildew, white and flour-like, 

 are frequent upon the lilac. Black perithecia are abundant 

 late in the season. 



LILY 



Botryose (Botrytis sp.). — This exceedingly destructive 

 mold of the lily was noted about 1885, and was first 

 closely studied by Ward' in 1888. It makes its appear- 



' Ward, H. M., Ann. Bot. II, No. 7, November, 1888. 



