Common Blight
Bacterial blight is a key pest of dry beans in Michigan. It is a collective term used to describe the symptoms on beans caused by one or more species of bacteria. Plant infection occurs through natural leaf openings, or through wounds created by hail, blowing soil particles, sucking insects, or mechanical injury. Pod infection occurs rapidly, after which immature seeds are invaded by the bacteria.

Common and Fuscous blight sypmtoms include small water-soaked spots on the underside of leaflets that enlarge and merge, becoming dried and brown. A narrow, bright lemon-yellow border of tissue often encircles the lesion. Infected pod symptoms include circular water- soaked spots and yellow masses of bacteria seen in their centers, when the spots dry they become reddish-brown sunken lesions. Early pod infection may cause shriveled seeds as well as yellowing under the seed coat. Spread from plant to plant is very rapid and warm weather favors infection.