VIII. THE BEAN BLIGHT 



(Syn. The bacterial bean spot) 



Type. — This is a disease of beans common on leaves, stems 

 and pods, and confined principally to the parenchyma although 

 the vessels also are invaded, sometimes for a distance of several 

 inches. It occurs on several species of beans (Phaseolus) and 

 is a serious disease. Whether other related genera are subject 

 remains uncertain. Similar looking bacterial diseases occur 



Fig. 213. — Portion of under surface of an immature bean leaflet showing 

 stomatal infections (light spots) due to a pure culture spray inoculation 

 of Bacterium phaseoli isolated from an Idaho bean. Time, 3 days. Spots trans- 

 lucent but not yet brown or sunken. Planar enlargement by James F. Brewer, 

 September 26, 1914. X 8. 



on cowpea (Vigna) and on soy bean (Mucuna), but my cross- 

 inoculations to plants of these genera failed (one trial only, 

 but using many plants and virulent cultures sprayed on the 

 foliage). A yellow organism resembling this one on agar and 

 potato was plated from spots on leaves of the soy bean in my 

 laboratory in 1902 from Charleston, South Carolina, and Wash- 

 ington, D. C, and again in 1917 from Norfolk, Virginia. 



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