These cankers continue to increase in size as long as conditions remain favorable for disease development. The cankers have a shrunken surface and appear dark brown to purple in color. If a canker girdles a stem, the whole stem can die. Blighted pear shoot. Twig infections can spread back into their supporting limbs and cause cankers.
Symptoms can develop rapidly.
Characteristic bend or shepherd s crook of a blight-affected terminal. The bacteria overwinter in cankers formed during the previous years infections and as resident bacteria on plant surfaces. As numbers of bacteria grow, they can be identified as droplets of bacterial ooze produced in the margins of cankers. When conditions become favorable for bacteria to grow, populations can build rapidly. The first new tissues to become infected in spring are the flowers, and, once infected, they serve as the source of inoculum for shoot infections.