342 



DISEASES OF CULTIVATED PLANTS 



the seed, which, however, shows no sign of disease, but when 

 sown produces a smutted crop. Seed should be sown that 

 was produced in a crop free from smut. 



Scilla smut (Ustilago Vaillantii, Tul.) occurs very com- 

 monly in the anthers and ovary of Scilla bifolia and other 



FIG. 1 02. Ear of barley attacked by Ustilago hor del. 



species ; Gagea lutea^ also in species of Muscari, Bellevalia^ 

 etc. The mycelium of the fungus is perennial in the stem or 

 cushion of the bulb, and from thence passes up the flower- 

 stalk and into the anthers or ovary each year ; hence when a 

 plant is once infected it remains so for all time, and it is 

 advisable to remove such bulbs, as the flowers are unsightly 



