Shortly after the blossoms die, leaves on the same spur or shoot turn brown on apple and most other hosts or black on pear. The stems and midribs of diseased leaves often turn black as well. As the twig and leaf blight phase progresses, leaves die, curl downward, and cling to the blighted twigs. Succulent twigs, shoots, and water sprouts are easily infected. Leaves may be infected through pores as well as wounds.
Cankers form at the base of blighted twigs and spurs.
The bark surrounding a developing canker first appears water-soaked, then later sunken and dry. The surface of bark covering the canker is usually smooth and sometimes has a purple color. Reddish-brown streaks can be seen in the sapwood under the discolored, sunken bark. Amber-colored discharge can often be seen near blighted tissues of the plant at any stage of infection. The fire blight pathogen, Erwinia amylovora, is a rod-shaped bacterium that overwinters in tissues around the edge of cankers on large branches and limbs.