Stewart's disease of maize: technic 167 



the final examinations in September before frost supervenes. 

 One or more of the following sensitive varieties may be used: 

 Black Mexican, Golden Bantam, Crosby's Early, Cosmopolitan, 

 Pocahontas. Along with these, white and yellow field corns 

 should be inoculated for comparison, taking pains to secure 

 the names of the latter. The seedlings should be ready for 

 inoculation about 8 days after planting, which, in the North, 

 should be toward the end of May, if the seedhngs are to be 

 transplanted into the open field. 



Uninoculated check-plants should be held. These should be 

 grown at some distance from the inoculated plants (preferably 



Fig. 108. — Cross-section of a small luuulle at the extieiue base of a kernel of 

 sweet corn showinp; Aplanobacicr slewarti in the single vessel. 



in an adjoining house) and should be transplanted to the other 

 side of the garden. Even then, some cases may be expected 

 unless the seed corn is beyond suspicion, and the house free from 

 insects. 



Determine 



For the organism. Morphology. — Size in microns, form 

 (Ziehl's carbol fuchsin or amyl Gram may be used for staining), 

 aggregation of elements, motility (hanging drop), question as 

 to occurrence of flagella (hanging drop and van Ermengem's 

 silver-nitrate stain; in case of the hanging-drop method, boil the 



