514 



FUNGI IMPERFECTI. 



sugar beet and beet-root. It is easily recognized by the 

 numerous sharply defined spots produced on the leaves. The 

 conidia are very long and pluriseptate. In the United States 

 this is one of the most serious of beet diseases.-' As preventive 

 treatment, great care should be taken to destroy aU infected 

 material. A long rotation should also prove a good remedy. 



Fig. 314. — Ccrcospora acti-ina. 2, Seedliog of Aca-^ with a cotyledon brown and 

 withered, and a leaf partially so. 4, Section through a diseased cotyledon ; the 

 conidiophores (d) emerge from the epidermis, and bear long tapering septate 

 'conidia; e, sclerotia formed inside the diseased tissues for hibematiOD. 5, Ger- 

 minating conidia. (After R. Hartig.) 



C. apii Fres. Common on celery {Apium graveolens) and par- 

 snips (Pastinaca sativa) throughout all Europe and North America. 

 It causes leaf-spots at first yellowish then enlarging and turn- 

 ing brown. The mycelium grows in the intercellular spaces of 

 the leaf, and gives off tufts of conidiophores through the 

 stomata. The conidia are long, tapering, obclavate bodies with 

 an attachment-scar at their larger end.^ 



C. asparagi Sacc. occurs on asparagus in Italy ; C. caulicola 

 Wint. frequents the same host in America. 



C. Bloxami B. et Br. On Brassica in Britain. 



0. armoraciae Sacc. On horse-radish. 



'Pammel, Iowa Agric. Sxper. Station Bulletin, 15, 1891. 



2 Description in New Jersey Agric. Exper. Station Bulletin 2, 1891. 



