STEWART'S DISEASE OF SWEET CORN (MAIZE). 



Synonyms: Bacterial Disease of Sweet Corn; Burrill's Disease of Maize pro parte (?). 



DEFINITION. 



This is a specific communicable disease of sweet corn and some other races of maize, 

 making its appearance at any stage of growth, but usually most noticeable when the plants 

 have attained a height of several feet. It is principally a disease of the vascular system, 

 which becomes filled with a yellow bacterial slime. The nodes are finally stained brown or 

 brownish, especially toward the base of the stem. The plants are dwarfed, the male inflo- 

 rescence develops prematurely and dies early, the leaves dry out one after another, much as 

 if frosted, and finally the stem dies and dries out, but without becoming soft-rotted. The 

 bacterial slime oozes to the surface of the inner husks. 



HOST-PLANTS. 



This disease has been observed only in Zea mays. The choice edible varieties known as 

 sugar-corn or sweet-corn are specially subject to it, but the writer once observed it in 

 autumn in common (dent ?) corn grown on damp land for fodder. It has been inoculated 

 successfully by the writer into several kinds of sweet-corn and into some kinds of field- 

 corn. Stewart's attempts to communicate the disease to pop-corn, dent-corn, teosinte, and 

 oats were not successful. 



GEOGRAPHICAL DISTRIBUTION. 



This disease has been observed on Long Island, New York, where it is widely distributed 

 and common every year (Stewart, Duggar, Smith), once in New Jersey (Halsted), several 

 times in Washington, D. C. (Smith), twice in Maryland (1908, 1909), twice in Virginia 

 ( 1 908) , once in West Virginia ( Enlows) , and once in Michigan ( Smith) . The writer has also 

 strong circumstantial evidence for believing that it occurs in Ohio. Nothing more is known 

 definitely of its distribution in the United States, and it has not been reported from any 

 other part of the world. It is to be looked for, however, wherever sweet maize is grown 

 extensively. Stewart assumed its occurrence in Iowa, which is not unlikely, but his evidence 

 is not conclusive. It probably occurs in Illinois. 



SIGNS OF THE DISEASE. 



The writer knows of no other disease likely to be mistaken for this one. The only con- 

 spicuous source of confusion is the autumn frosting of the foliage, after which diseased and 

 healthy plants can not always be discriminated by mere inspection, since the bacterial slime 

 does not ooze from the ends of cut stems after frost has destroyed the leaves. They may be 

 separated easily by microscopic examination. 



In the fields on Long Island one of the first signs, in good-sized plants, is the whitening 

 (drying out) of the male inflorescence. This is stimulated to premature development and 

 soon dies, giving to the top of the plant a peculiar whitish appearance. This sign comes 

 rather in advance of the drying out of the leaves, except some of the inconspicuous lower and 

 smaller ones, and may appear on a plant which in other particulars looks entirely healthy. 

 In only one or two instances out of many did subsequent dissection fail to confirm the 

 writer's diagnosis based on what appeared to be the premature development of the male 

 inflorescence, and in no case were the bacteria wanting in the bundles when this inflorescence 



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