Frog-eye leaf spot can be confused with foliar chemical injury and isolation is necessary for a positive identification. The bacterium responsible for fire blight usually attacks blooms first. Blossoms wilt and turn brown. Bees which are essential for pollination can spread the bacterium from bloom to bloom. As the disease progresses down into the woody tissue, water-soaked bark is noticeable.
Infected branches die back and leaves turn brown.
A bacterial ooze frequently occurs on infected branches and occasionally the ooze can be seen on immature fruit. A heavily infected tree looks as if it has been damaged by fire. Dead wood produced by fire blight provides areas for secondary fungus infection by other fruit rotting organisms. Fire blight of apple. On the leaf, scab causes an olive green spot somewhat darker than the leaf tissue.