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Bacterial brown spot of beans
Pseudomonas syringae pv. syringae
Synonyms
 
  • bacterial brown spot

Plant hosts
 
All Phaseolus crops are susceptible to bacterial brown spot of beans including Phaseolus acutifolius (tepary bean), P. coccineus (runner bean), P. lunatus (lima bean), and P. vulgaris (common bean).
 

Symptoms
 
Leaf symptoms begin as small circular, brown spots with a narrow yellow border.  Lesions can enlarge, coalesce, and turn necrotic with the dead tissue falling out giving the plant a ragged appearance.  Sunken brown spots may also develop on pods.  As infected pods grow, they may become distorted at the area of the lesion.
 
Symptomatic leaves Symptomatic beans
 
Symptomatic leaves.                            Symptomatic bean pods.
 
Images courtesy of M.T. McGrath.
 

Transmission
 
P. syringae pv. syringae can survive on a number of crop and non-crop plants which serve as a source of inoculum.  Bacteria are then spread with water during irrigation or rainfall.  Infected seed is another avenue of spread.
 

Geographic distribution
 
Bacterial brown spot of beans is distributed worldwide.
 

Applicable regulations
 
603-052-0385, Bean disease control area order; Malheur County
 
Return to plant pathogen profile list.