618 THE FUNGI WHICH CAUSE PLANT DISEASE 



S. citri Pa. & Ch.=" 



Vegetative mycelium long, hyaline, becoming dark, 4 /» in 

 diameter, septate; conidiophores short; conidia dark brown, sub- 

 globose to oblong, apiculate, irregularly muriform, 20-30 x 12- 

 15 n, usually in chains of three. 



This was found associated with an end-rot of oranges from 

 Arizona. Inoculated in pure culture in oranges the fungus de- 

 veloped well. It is perhaps the cause of the disease. 



S. tritici Pa. 



Hyphffi irregularly branched; conidiophores closely septate, 

 4-5 M in diameter; conidia catenulate, irregular, usually clavate, 

 constricted slightly at the septa, 24-35 x 12-15 fi, vermiculate, 

 fuligineus, isthmus short, 3-4 /t in diameter. It is described as 

 the cause of floret sterility of wheat."^'^"- '"• *'* 



Macrosporium Fries (p. 616) 



Conidiophores fasciculate, erect or not, more or less branched' 

 colored; conidia usually apical, elongate or globose, dark-colored. 



In part=Pleospora. See p. 259. 



About one hundred- eighty species, many of them saprophytes 

 while others are important pathogens. 



M. commune Rab.=M. sarcinula parasiticum Thiim. on vari- 

 ous grasses =Pleospor a herbarium. '"• ''* See p. 260. 



This is reported by Thaxter '" as the common black mold which 

 follows Peronospora on the onion and which occurs often also on 

 onions not so diseased, being especially common on the seed stalks. 

 It is usually associated with injured plants and may be important 

 only as a wound parasite. 



M. porri E.'" 



Effuse, fuUgineus; hyphje short, simple, subfasciculate; conidia 

 elongate-clavate, basally attenuate, multiseptate, 150-180 x 

 12-20 n. 



It is common on seed onions, less common on market onions. 

 The dark mycelium penetrates the host in all directions and finally 

 produces stromata below the stomata and sends up short hyphjs. 



M. alliorum C. & M. is also on onion; ^* 



M. hurculeum E. & M. 



Amphigenous on rounded, grey spots; conidiophores erect, ces- 



