University of Missouri Extension

G4442, New December 2004

Soybean Rust

Bacterial blight
Pseudomonas savastanoi pv. glycinea

Bacterial blight, upper leaf surface Upper leaf surface


Bacterial blight, lower 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.

Canopy symptoms

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.

Weather

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.

Survival

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.

G4442, new December 2004

G4442 Soybean Rust | University of Missouri Extension

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