CHAPTER II. 



FUNGOID DISEASES OF CEREALS AND GRASSES. 



I. Smuts. Class: Teliospore^ ; Order: Us- 

 TiLAGiNALES ; Family : Ustilaginace^. 



Smut is also known to the farmer as dust brand, 

 chimney sweeper, sleek, slean, etc. 



The cause of all smut of the small o-rains was 

 previously set down to a single species to which the 

 name Ustilago cai^bo was given : recent research 

 has shown that the smut of different trenera of 

 grasses is caused chiefly by species of Ustilago, but 

 in many cases of other genera as well. The econ- 

 omically important forms, however, are mostly 

 species of Ustilago. 



(a) Oat Smut i^Ustil ago Avence)} — Much damage 

 is caused in certain districts by this fungus. 



Symptoms. — Plants which up to the time of the 

 appearance of the ear have looked quite healthy 

 are found to produce, instead of grain, a brownish 

 black powder, which is easily carried and distributed 

 by the wind, leaving nothing but the bare straw at 

 harvest time. 



' A closely related species, U. Icevis, has been found along with 

 this species, the spores of which are perfectly smooth. 



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