CEREALS 371 



known that with the loose smuts of wheat and barley, totally 

 unlike the bunt of wheat and the loose smut of oats, infec- 

 tion occurs exclusively at blossoming time; that at all other 

 times the plants are immune. Smut spores from near-by 

 smutted heads are blown into the wheat or barley flowers. 

 Infection follows. The fungus then lies dormant in the 

 grain until the seed sprouts. If the grain ripening from 

 such infected flowers be used for seed, the fungus develops 

 in the seedling, and an infected plant, producing smut but 

 no grain, results, though no external s3rmptom of the disease 

 appears until blossoming time. Conversely, if seed result- 

 ing from blossoms which were not infected be used, plants 

 free from smut will be raised. 



The remedy in this case, therefore, lies in the use of unin- 

 fected seed. To obtain such seed grain must be secured 

 from a mother field in which there is no loose smut, or if 

 this is not practicable, seed grain must be raised under such 

 conditions as will afford clean seed. 



It has been found that while formaUn, as a seed treat- 

 ment, is ineffective against barley and wheat loose smuts, 

 the Jensen hot-water treatment, in modified form, is effec- 

 tive, and it could be used directlj^ as a preventive, were 

 it not that it is too difficult of manipulation to be apph- 

 cable to large quantities, and that its use seriously en- 

 dangers germination of the seed unless applied with great 

 care. 



Rouging, or weeding out all diseased plants' from the 

 crop that is to be used for seed, diminishes the smut largely, 

 but does not entirely eliminate it. 



A practicable, effective means, which results in complete 

 and inexpensive eradication of this smut, consists of a com- 



