CEREAL PESTS PARASITIC FUNGI 519 



was formerly supposed. It is difficult to distinguish it by 

 casual observation from the naked or loose smut, though, 

 as a rule, the smut masses or balls are inclosed by the outer 

 glumes of the florets, whereas in the case of the loose or 

 naked smut, the whole spikelet is generally destroyed, 

 including the outer glumes. The spores of the covered 

 smut are smooth, whereas those of loose smut are minutely 

 echinulate. The covered smut may be controlled by the 

 same method of seed treatment recommended for the 

 prevention of loose smut (Fig. 159 a). 



562. Covered smut of barley (Ustilago hordei, Kell. & 

 Sw.). This smut, while it is very generally distributed 

 throughout barley-growing districts, is not responsible 

 for such great losses as is the loose smut of oats. Because 

 of its manner of development, it is frequently overlooked 

 even when present in considerable quantities. It resem- 

 bles, in its life-history, the smuts of oats in many respects, 

 and, like the latter, infects the seedling of the host. If 

 the smut is present when barley is sown, and suitable 

 conditions prevail, the spores will germinate and produce 

 conidia, which will infect the young seedlings while they 

 are still very small and beneath the soil. The parasite 

 grows with the host, and finishes its development in the 

 spikelets of the barley. These diseased ovaries remain 

 closed and are not broken, as in the case of a loose smut, 

 until thrashing time, or even later (Fig. 160). 



563. Prevention of bunt, oat smut, and covered smut of 

 barley. The most effective methods of seed treatment 

 for these smuts are those involving the use of the fungi- 

 cides formalin and copper sulfate. In Europe and in parts 

 of this country, the Jensen hot-water treatment is used 

 to good effect. 



These fungicides are applied in two ways by steeping 



