628 



THE FUNGI WHICH CAUSE PLANT DISEASE 



C. apii Fr. 



Spots amphigenous, subcircular, pale-brown, 4-6 mm. in diame- 

 ter, with a more or less definite elevated margin; conidiophores hy- 

 pophylous, light-brown, fasciculate, con- 

 tinuous or 1 or 2-septate, subundulate, 

 40-60 X 4-5 n; conidia hyaline obclavate, 

 or almost cylindric, 3 to 10-septate, slen- 

 der, 50-80 xi II. 



A serious leaf spot is produced on celery, 

 parsnips, etc.'^""'^^ 

 C. beticola Sacc."' ^sa 

 Spots amphigenous, brownish, purple- 

 bordered, becoming ashy centered; co- 

 nidiophores fasciculate, short, simple, erect, 

 flavous, 35-55 x 4-6 ft; conidia elongate, 

 filiform obclavate, hyaline, multiseptate, 

 75-200 X 3.5-4 n. 



This fungus, described in 1873, causes 

 a very serious disease of beet producing 

 spots on the leaves. It is common and de- 

 structive in America and Europe. The 

 conidiophores usually, though not always, 

 emerge from the sto- 

 mata from a few-celled 

 stroma and are amphig- 

 enous. They vary in 

 length and septation 

 with age. If in humid 

 atmosphere the spots 

 become hoary, due to 

 spores present. Each 



capable of germination. The germ tubes 



infest the host through the stomata. Pure 



Fio. 427.— Fertile hy- cultures of the fungus may readily be se- 



&.*betkola.''°1iter Cured by the usual methods. Here the 



Duggar. myceliiun produces dense matted colonies 



of deep olive color and a greenish-grey aerial growth but no 



conidia. Found also on Spinach in Texas. 



Fig. 426.— C. apii. After 

 Duggar and Bailey. 



the large nimtiber of 

 cell of the spore is 



