198 



related with loss, since infected stalks are usually sterile or bear only 

 nubbins. 



Control consists in using carefully selected seed known to be nearly 

 disease-free. 



Stewart's Disease 



Caused by Pseudomonas stezvarti E. F. S. 



One of the serious diseases of corn is Stewart's disease. Ordinarily 

 it is most serious on sweet corn, but under certain conditions field corn 

 may also suffer severely. The bacterium which causes the disease in- 

 vades and plugs up the fibers of the stalks, thus interfering with the 

 development of the plant. 



Stewart's disease is known to occur in 9 counties as shown on 

 Map 23. 



An examination of sweet-corn fields in seven counties during 1923 

 indicated that an average of 13 per cent of the stalks were diseased. 

 Such a percentage of infection is certain to result in a noticeable re- 

 duction in yield and indicates the necessity for using early-maturing 

 varieties. Northern-grown seed appears to be least often diseased and 

 may be used to advantage. 



Rye 



Rye is one of the less important of the cereals grown in Illinois, 

 coming after oats but before barley, and the crop of the state has had 

 an annual valuation of approximately $0,000,000 during recent years. 

 Small acreages are to be found in every county in the state, but the 

 greatest acreage is in northwestern and western Illinois, where, in 1922. 

 it reached a total of 120,000. The smallest acreage is in the extreme 

 southern tip of the state, where, in 24 counties, only 4,000 acres were 

 planted in 1922. The distribution of rye acreages is shown on Map 24. 



Brown Rust 



Caused by Pitcciiiia dispcrsa Eriks. 



Brown rust is the most common and most serious disease of rye in 

 Illinois. It is comparable on rye to the leaf rust (P. triticina Eriks.) 

 of wheat. It appears especially on the leaves, where it produces small 

 oval spots, distinguishable from the spots of stem rust in part by their 

 position on the plant but more particularly by their much smaller size 

 and definitely brownish color. The amount of infection is generally 

 light, and the loss is usually estimated as a trace to 2 per cent. 



Early reports of brown rust in Illinois are few. A. B. Seymour 

 made the first collection in La Salle county in June, 1882; Burrill reports 

 its presence in Champaign county in 1911; and a collection was made 

 by H. \V. Anderson at Urbana, Champaign county, June 10, 1919. 



