174 



BACTERIAL DISEASES OF PLANTS 



oculated plants to become potbound? Can you cause general 

 infection by stem inoculations of half-grown plants? Inocu- 

 late in the middle of internodes and also close under nodes. 

 Does nodal inoculation make any difference, i.e., hasten 

 infection? 



If you have opportunity, examine infected fields and make 

 lists of susceptible and resistant sweet corns. Make extensive 



Fig. 116. Fig. 117. 



Fig. 116. — Longitudinal section of two sweet-corn stems showing a brown node 

 and yellow stripes in the internodes, and a bacterial cavity in the middle of the 

 left-hand stem. This cavity was bright yellow. Sections from plants inoculated 

 in the seedling stage. 



Fig. 117. — Stained .section of such a stem as Fig. 102 enlarged showing two 

 bundles occupied by Aplanobacter stewarti and two free. 



counts and express your data in per cents. Reexamine your 

 fields some weeks later for additional cases. 



Remember: none of the diseases described in this book are 

 known thoroughly and you may have opportunity to add to the 

 sum of our knowledge. 



Transmission. — This is commonly by way of seed corn. 

 Very likely also by way of soil previously infected. Read what 



