370 DISEASES OF ECONOMIC PLANTS 



The seedling age, like that of the oat, is the only age sus- 

 ceptible to smut infection. Treatment of seed wheat with 

 formalin, as recommended for oats, is complete in its effi- 

 ciency and trifling in cost. If formahn is not obtainable, 

 immersion for twelve hours in one half per cent solution of 

 copper sulphate (2 pounds to 50 gallons of water), then in 

 milk of lime (2 pounds of lime to 20 gallons of water), for 

 five minutes is recommended. The use of the lime cannot be 

 omitted without endangering the germinating power of the 

 seed. There is but little choice between these two treat- 

 ments for wheat, though the formalin is perhaps safer in its 

 effect upon the germinating power of the seed, especially if 

 the lime is not used with the bluestone. The hot-water 

 treatment, see p. 372, is serviceable but more laborious 

 than either of the others. In any of these methods the 

 seed must be dried, and the drill disinfected. See p. 346. 



Loose smut (Ustilago Tritici (Pers.) Jens.). — Like the 

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

 importance. In some regions it prevails to a greater 

 extent than the bunt, causing at times a loss^of more 

 than half the crop. It may be readily disting-uished 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, 1896, in Tasmania, Wa- 

 kagwa in Japan, Brefeld in Germany, and others, it is 



