280 Diseases of Economic Plants 



and the difficulty and expense of the application. Moreover 

 the question of use of such treatment is complicated by the 

 different kinds of rusts to be met and by their different 

 behavior in different seasons. 



Anthracnose of Cereals 



Anthracnose ^"'^ {CoUetotrichum cereale Manns). — Upon 

 many cereals and forage crops, as rye, wheat, oats, orchard 

 grass, timothy, red-top, and blue-grass, occurs a blight, 

 resulting in shriveling of the grain and spotting of the leaves 

 and stalks. The fungus is marked by small, black acervuli, 

 located upon the spikes, stems, and sheaths. The chief at- 

 tack is made as the plants approach maturity. 



For further discussion, see rye. 



Special Diseases of Cereals 

 BARLEY. 



Loose-smut '^-^ {Ustilago nuda (Jens.) K. & S.). — This 

 disease, previously thought insignificant, seems to be in- 

 creasing in importance. It now often causes losses in Wis- 

 consin and Minnesota of from 5 to 10 per cent of the crop, 

 and is generally prevalent in this country, though often 

 unnoticed on account of the early season of its development, 

 and its absence at harvest time. Every spikelet of the 

 smutted head is usually affected and entirely changed into 

 smut, the central stalk of the head alone escaping. Adjacent 

 leaves are also occasionally smutted. 



The smut masses, when they first appear, are covered by a 

 white or gray membrane which soon ruptures, loosing a 

 powdery, olive-brown mass of spores, which soon blow 

 away. This character enables one to distinguish it easily 

 from the covered smut. Smutted plants head early, the 

 smut reaching its maximum at flowering time, though 

 scattered heads of smut may appear at other periods. The 

 smutted heads stand high on tall stalks, which affords ex- 

 cellent wind distribution of the spores to the surrounding 



