300 Minnesota Plant Diseases. 



Broom corn smut [Sphacelotheca sorglii (Lk.) Clinton]. 

 This is the same fungus that causes the grain smut of sorghum. 

 When it attacks the broom corn, it seriously affects the forma- 

 tion of the brushes and the smut often discolors them. The 

 young grains and stamens may become smutted and usually all 

 of the grains of a cluster are destroyed. The spore mass is very 

 dark and the spores have an olive-colored tint. The host plant 

 is apparently infected only in the seedling stages and hence care 

 must be taken to avoid the presence of spores in a seed mixture. 



Seed broom-corn should be treated in hot water in the usual 

 way at a temperature of 135 degrees Fahrenheit for ten to fifteen 

 minutes. Such treatment of seed will largely if not entirely pre- 

 vent the smut. It is probable that the formalin method would 

 also be effective. 



Naked barley smut [Ustilago nuda (Jens.) Kell. and Sw.]. 

 The naked smut is more common than the covered smut of bar- 

 ley and also more difficult to combat. This smut attacks the 

 grains and forms smutted heads, which do not, however, remain 

 closed as long as do those of the covered smut. The smut 

 masses are at first enclosed in a membrane, but the spores do 

 not adhere so closely and when the membrane of the head breaks 

 the smut spores are quickly dispersed by the wind. The heads 

 of barley have then the appearance of wheat affected by loose 

 smut. The awns of the barley head are either only stunted or 

 may remain intact. The powdery spore mass is dark and black, 

 with a greenish tinge, differing in this respect from the covered 

 smut of barley. Tlie exact method of infection of the host plant 

 is unknown but there seems to be some evidence that it is not 

 in the seedling stage. 



"Soak the barley seed four hours in cold water and then let 

 it stand four hours longer in a wet sack. Finally dip and drain 

 as directed in the treatment for oat smut for five minutes in wa- 

 ter at a temperature of 126 to 128 degrees Fahrenheit, after 

 which dry and plant as in case of smut of oats." (Kansas Ex. 

 Sta. Rep. for 1889, p. 284.) This treatment is also ample for 

 the covered smut. 



Covered smut of barley [Ustilago hordci (Pers.) Kell. and 

 Sw.]. This is one of the two common smuts which attack the 

 barley plant. The smut spores are formed in the very young 



