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, Anti. Rep. Co?t?i. Agric. Expt. Statio?i, p. 129, 

 pi. 2 (1890). 



Weed, Fungi and Fimgicides^ p. 152. 



COLCHICUM SMUT 



{Urocystis colchici, Rab.) 



This smut often forms long rows of black, powdery 

 streaks on the leaves of Colchiciim {Colchicum autiininaie), 





^if 





1^ * "'^31^ 



t» 



^- 



f 



i^ }:A 



it ' 



Vmr 





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

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



Muscari racemosiwi, M. co??iost(fn, Scilla bifolia, Allhini 

 rotundum, A. cepa, A. ?nagic2i?n, and Paris quadrifoiia. 



