PLATE 28 



A. — Pycnidia of Cytospora chrywsperma on Poi)ulus alba after the spore horns have 

 been washed away by rains. 



B. — A young plant of Populus italica, showing the upper portion of the stem killed 

 by inoculation with C. chrysosperma. Sprouts are putting out below the point of 

 inoculation. 



C. — Two tubes of pure cultures of C. chrysosperma on malt agar, showing pycnidia 

 and spore droplets. 



D. — A propagation cutting of Populus delioides from Hays, Kans., killed by C 

 chrysosperma. 



(345) 



