THE FUNGI WHICH CAUSE PLANT DISEASE 279 



Fig. 208.- 

 in section 

 lasne. 



Diaporthe. 

 C, asci. 



o 



B, stroma. 

 After Tu- 



hyaline, appendaged or not; pa- 

 raphyses none. Conidia=Phoma, 

 Cytospora, etc. 



D. taleola (Fr.) Sacc. 



Stroma cortical, definite, de- 

 pressed, pulvinate, 2-4 mm., cov- 

 ered; perithecia few, 4-10, buried, 

 their ostioles converging, erumpent 

 in a small light-colored disk; asci 

 cylindric, 120-140 x 10-12 ix, spores 

 elliptic, uniseptate, constricted, with 

 setaceous appendajges, 15-22 x 

 8-9/1. 



It causes canker on oak, killing 

 the cortex over large areas. A 

 year later the cushion-like stromata 

 appear. The myceliimti penetrates 

 both wood and bark, probably enter- 

 ing through wounds. 



D. albocarnis E. & E. on Comus is destructive. 



D. ambigua and D. sarmentella are on pear and hop, D. stru- 

 mella on a wide range of hosts, in conidial form as Phoma. 



Melanconidaceae (p. 223) 



A small family of less than two hundred species contains only 

 four parasitic genera. 



Stroma pulvinate, sunken; perithecia sunken in the stroma, 

 the mouth erumpent; asci cylindric or clavate; paraphyses present. 



Key to the Geneba of Melanconidaceae 



Spores 1-celled, hyaline 



Spores ellipsoid or short-fusiform 1. Ciyptosporella, p. 280. 



Spores elongate-cylindric, curved 2. Ciyptospora. 



Spores 2-ceUed 

 Spores hyaline 

 Conidia in pycnidia; 1-celled, hyaline. . 3. Valsaria. 

 Conidia not in pycnidia, dark brown. . 4. Melanconis, p. 281. 

 Spores brown 5. Melanconiella. 



