224 PLANT DISEASES 



not be sown for some years. The disease appeared in one 

 instance after a period of twelve years' rest, due presumably 

 to smut-spores still present in the soil. 



Thaxter, Ann. Rep. Conn. Agric. Expt. Station, p. 129, 

 pi. 2 (1890). 



Weed, Fungi and Fungicides, p. 152. 



COLCHICUM SMUT 



( Urocystis colchici, Rab. ) 



This smut often forms long rows of black, powdery 

 streaks on the leaves of Colchicum (Colchicum autumnale), 



i ' , J fJ 



' 



Q 



Fig. 54. Urocystis colchici. i, Portion of a diseased leaf, 

 nat. size ; 2, a single sorus, slightly mag. ; 3, spores, x 300. 



Muscari racemosum, M. comosum, Scilla bifolia, Allium 

 rotundum* A. cepa, A. magicum, and Paris quadrifolia. 



