201 



tion of the state, and it is here that the diseases of barley are of most 

 importance. 



Leaf Rust 



Caused by Piiccinia simplex (Koern.) Eriks. & Henn. 



Leaf rust of barley, which is similar in appearance to the leaf rusts 

 of wheat and rye, is not known to be of common occurrence or to be 

 widely distributed in Illinois. It is known to occur in the two counties 

 shown on Map 30, but is undoubtedly prevalent at least throughout 

 northern Illinois. 



Stem Rust 

 Caused by Pitccinia graniitiis Pers. 



Stem rust appears to be of comparatively rare occurrence on barley 

 in Illinois. In appearance it is the same as stem rust on wheat, oats, 

 and rye. Wild barley {Hordeum jubatum L.) is often infected with 

 stem rust, but it appears not to have been definitely recorded as appear- 

 ing on cultivated barley jjrevious to litLS. In that"year H. W. ,\nderson 

 collected a specimen of it near Halfway, Williamson county. 



Stem rust is now known to occur on barley in the si.\ counties shown 

 on Map 31. As seen in the northern counties, the infection was much 

 more severe than is usually found on the other cereals subject to this 

 disease. 



Eradication of the common barberry in the northern counties should 

 help to control this disease. 



Loose Smut 



Caused by Ustilago nuda (Jens.) K. & S. 



Loose smut of barley is the most serious of the barley diseases. In 

 appearance it is very similar to loose smut of wheat. The heads are 

 transformed to masses of loose black jjowder. The spread of infection 

 occurs at blossoming time, and diseased grains, which develo]) in an 

 ap])arently normal way, perpetuate the smut. Plants growing from in- 

 fected grain produce the worthless smutted heads. 



The known distribution of loose smut, as shown on Map 32, in- 

 cludes 11 counties, of which i) lie in the northern part of the state, and 

 6 are important barley ])roducers. The disease ajjpears widely distrib- 

 uted over the state, but is found most alnmdantl)' in northwestern Illi- 

 nois in the region where the barley acreage is greatest. During Il)2.3 

 examinations made in 11 fields distributed among li counties and includ- 

 ing '.ViSi acres indicated that an average of (!.l ])cr cent of the stalks 

 were diseased. This is equivalent to a cro]) reduction of the same amount. 

 While this figure may not be re])resentative of the amount of disease to 

 be found in all the fields of the state, it is indicative of the seriousness 

 of the disease and em])hasizes the value of seed treatment. The methods 



