PLANT DISEASES 



273 



and methods of combating, the smuts of cereals may be 

 divided into three groups. 



i. Stinking Smut of Wheat, Oat Smut, and Covered 

 Smut of Barley. These three smuts, although dis- 

 tinct, have a similar life story, which was 

 briefly described above. The smut spores 

 cling to the grain over winter, are planted 

 with the seed, and grow when the grain 

 grows. The threads which are thus pro- 

 duced by the spore get into the grain 

 plant and grow up with this plant until 

 heading-out time. The threads then fill 

 the kernels and convert them into a black, 

 smutty mass. As pointed out above, the 

 treatment of the seed is clearly the most 

 efficient method for treating this class 

 of diseases. If, for instance, one puts 

 the seed in hot water at about 130 F. 

 (for details of treatment see various State 

 Experiment Station and United States 

 Agricultural Department bulletins) for ten 

 to fifteen minutes, the smut spores on the 

 outside of the grain are killed, while the 

 grain itself is not injured. Careful wash- 

 ing of the seed will also remove a good 

 many of the spores. Other methods are (After G. p. ciin- 

 useful in connection with this group. 

 For instance, a 40 per cent solution of formaldehyde 

 (which can be obtained in any drug store) when mixed 

 with water in the proportion of one pint to about forty 

 gallons can also be used. This solution poisons the 

 spores and kills them, while it does not affect the grain 

 even if the grain is allowed to stay in it for two hours. 



M. & H. AG. - l8 



G ' 





