Upper leaf surface
Lower leaf surface
Upper leaf surface symptoms
Bacterial blight begins as small, angular, yellow lesions in the leaf tissue. Lesions usually have a translucent or water-soaked "halo" that may be more readily seen if leaves are held up to the light. Lesions progress in color from yellow to light brown to a dark reddish or blackish brown. Lesions may enlarge or merge, producing large, irregular dead areas in the leaf. With wind and rain these large dead areas drop out or tear away giving the leaf a ragged appearance.
Lower leaf surface symptoms
Lesions on the lower leaf surface resemble those on the upper leaf surface.
The bacteria that cause bacterial blight are spread by wind-driven rain. Outbreaks typically develop several days after a rainstorm or hailstorm. Symptoms are most evident on growth that is expanding at the time of the rain event.
Bacterial blight is favored by cool, rainy weather. Symptoms typically occur several days after a rain with driving winds or a hailstorm. Hot, dry weather checks disease development.
The bacterial blight pathogen survives in infested residues left on the soil surface and may be seedborne.
Distribution in Missouri
Bacterial blight can occur throughout Missouri. It will be most prevalent in seasons with extended periods of wet weather and frequent storms with strong winds or hail.