CEREALS 351 



surfaces, sometimes so abundant as to lend a blackish 

 hue to the leaf, comprise the diagnostic symptoms of this 

 malady. Eventually the leaves are killed. 



Pseudomonose (Pseudomonas Avence Manns). — A disease 

 prevalent throughout the entire Eastern and Central 

 States was attributed to bacteria by Galloway and South- 

 worth in 1890.' It appeared when the plants were only 

 about 10 cm. high, first causing the leaves to turn brown 

 and die at the tips, then throughout their length. The 

 affected plants revived, but were so reduced in vigor as to 

 prevent effective stooling, and a loss of 35 to 75 per cent of 

 the crop followed. 



The disease has recently been carefully investigated by 

 Maims,^ who claims that it is caused by the symbiotic 

 action of two species of bacteria, a pseudomonas and a 

 bacillus. 



Manns describes the disease as follows : — 



The preliminary effect is yellowing of the leaf, beginning 

 either as small, round lesions on the blade, or as long, streak- 

 like lesions extending throughout the blade and even the 

 whole length of the culm and blades. Occasionally it begins 

 at the tips and works back into the culm ; again the upper 

 leaves often break down through a weakened condition of 

 the plant from defohation below. 



The ultimate symptoms, wherever the disease has made 

 much progress, are partial or general collapse of the leaves, 

 which take on a mottled to almost red color. 



It prevails from New England to Georgia, and from the 

 Atlantic to Indiana and Illinois. The damage in Ohio has 



! Galloway, B. T., and Southworth, E. A., Jour. Mycol. 6, 72. 

 ' Manns, T. F., Ohio Agr. Exp. Sta. Bui. 210, October, 1909. 



