248 THE FUNGI WHICH CAUSE PLANT DISEASE 



oblong, rather pointed, upper cell in the ascus somewhat larger 

 than the others, 28 x 6.5 m- 



Conidia of two kinds, (1) (=Cladosporium herbarum) tufts 

 dense, forming a velvety blackish-olive, effused patch, conidio- 

 phores erect, septate, rarely branched, often nodose or keeled; 

 conidia often in chains of 2 or 3, subcylindric pale-olive, 1 to 

 3-septate, 10-15 x 4-7 /x- (2) (=Hormodendrum cladosporioidies 

 Sacc.) Hyphae erect, simple, bearing apically or laterally a tuft 



Fig. 183. — M. citrullina, A. pycnidium (Diplodia) in seo- 

 tion, B, perithecium; C, 3scus and spores. After Grossea- 

 bacber. 



of small, elliptic, continuous, brown conidia in simple or branched 

 chains. 



It is the cause of serious disease in Europe, being especially 

 injurious to cereals after a rainy season preceded by a drought 

 and is found also parasitic on pea, apple, raspberry, cycad, agave 

 and as a saprophyte almost anywhere. 



M. stratifonnans Cobb, affects sugar cane. The perithecial 

 stage alone is known.^^^ Further study is desirable. 



M. gossypina (Cke.) Er."'"''" 



Perithecia ovate, blackish, partly immersed, 60-70 x 65-91 /*; 

 asci subcylindric, 8-10 x 40-45 fi; spores elliptic to fuSoid, con- 

 stricted at the septum, 3-4 x 15-18 ft. 



Conidia (=Cercospora gossypina); hyphs flexuose, brown. 



