III. STEWART'S DISEASE OF MAIZE 



Type. This is a vascular disease confined principally to 

 sweet corns, especially those rich in sugar and ripening early, 

 but it has been seen by the writer upon several varieties of 

 field corn. The foliage shrivels gradually, the lower leaves 

 usually first (Fig. 100) ; the male inflorescence develops pre- 



FIG. 100. Large sweet-corn plant destroyed by Aplanobacter stewarti. . A 

 natural infection. Bundles of the stem occupied by the yellow slime. District 

 of Columbia, 1903. 



maturely and is white (Fig. 101); and on cross-section or lon- 

 gitudinal-section of the stem a yellow slime oozes from the 

 vascular bundles (Figs. 102 and 103); stooling also sometimes 

 occurs (Fig. 104). Infection takes place principally in the seed- 

 ling stage through stomata and is greatly favored by actively 

 functioning water-pores situated on the young leaf-tips. The 



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