372 FUNGOUS DISEASES OF PLANTS 



1. Spores single, spore masses dusty, spores without conspicuous tube-like 



hyaline appendage Tilletia 



2. Spores single, Spores in loose groups, imbedded in the tissues. Entyloma 



3. Spores agglutinating in balls, spore masses dusty, spore balls invested 



with a cortex of sterile cells . . . .. : . ".'.". . Urocystis 



II. LOOSE SMUT OF OATS 

 Ustilago Avena (Pers.) Jens. 



JENSEN, J. L. Om Kornsorternes Brand. Copenhagen, 1888. 



KELLERMAN, W. A., and SWINGLE, W. T. Loose Smut of Cereals. Kansas 

 Agl. Exp. Sta. Kept. 2: 213-288. pis. 1-9. 1890. 



KELLERMAN, W. A., and SWINGLE, W. T. Additional Experiments and Ob- 

 servations on Oat Smut. Kan. Agl. Exp. Sta. Built. 15: 93-133- l8 9- 



STUART, W. Formalin as a Preventive of Oat Smut Ind. Agl. Exp. Sta. 

 Built. 87: 1-26. 1901. 



SWINGLE, W. T. The Grain Smuts. U. S. Dept. Agl. Farmers' Built. 75 : 

 1-20. figs. 1-8. 1898. 



The loose smut of oats is one of the most common and destruc- 

 tive of the smut family. It is found wherever oats are cultivated, 



and it would not appear that 

 climatic conditions influence 

 materially the abundance of 

 the fungus. Besides the vari- 

 ous varieties of the cultivated 

 oats (Avena sativa), it has only 

 been reported upon Avena 

 fatua, the latter in California. 

 Like most of the other 

 loose smuts of grain, it ma- 

 tures at or about the time the 

 grain is in flower, and dur- 

 ing the ripening season it is 

 widely distributed. The gen- 

 eral appearance of the loose 

 smut is striking, and usually 

 as shown in Fig. 189. It has 

 been estimated that the aver- 

 age loss to the oat crop 

 throughout this country may 

 FIG. 189. LOOSE SMUT OF OATS be placed at about eight 



