Cereals 315 



present and the heads only are harvested, the sickle-bar 

 may be so adjusted as to leave the bunt behind. 



Many smut spores naturally find lodgment upon the sur- 

 faces of healthy grains from smutted fields, or they may be 

 carried from farm to farm upon the threshing machine. Upon 

 planting such seed the following season these spores are 

 ready to attack the seedling grain plant. The fungus, after 

 gaining entrance into the seedling, grows with it throughout 

 the season, and appears again at harvest time as spore masses 

 within the chaff. Every grain of every head of an affected 

 plant is usually snmtted. 



The seedUng age, like that of the oat, is the onh^ age sus- 

 ceptible to smut infection. Treatment of seed wheat with 

 formalin is usually complete in its efficiency and trifling in 

 cost. In some sections of the Northwest, however, the soil 

 has become so heavily infested from previous cropping and 

 by "smut showers" that formalin seed treatment is of but 

 little value. In such regions early sowing and crop rotation 

 are reconmiended. 



Loose-smut ^-^ {Usiilago tritici (Pers.) Rostr.). — Like the 

 loose smut of barley, this smut seems to be increasing in 

 importance. In some regions it prevails to a greater ex- 

 tent than the bunt, causing at times a loss of more than a 

 quarter of the crop though the loss is usually not more than 

 2 per cent. Loose-smut may readily be distinguished from 

 stinking-smut of wheat by the fact that the spore masses 

 involve the whole spikelet, which becomes dry and powdery 

 and falls away; also by its much earlier appearance in the 

 field, i. e., at flowering time. The spore masses are dark, 

 olive-black, and are produced exclusively in the spikelets. 

 The bearded spring wheats seem to be more susceptible 

 than the blue-stem varieties, but the smut is common on all 

 varieties. 



From the studies of Maddox in Tasmania, Wakagwa in 

 Japan, Brefeld in Germany, and othei's, it was known in 1896 

 that with the loose-smuts of wheat and barley, totally unlike 

 the bunt of wheat and the loose-smut of oats, infection 



