While you'll most often see Fireblight disease on ornamental pear trees, it can also infect Indian Hawthorn, Loquat, Rose, Photinia and many more species. Plants in the rose family are especially susceptible. Fireblight disease is caused by bacteria and it can quickly spread. At first you'll notice what appears to be water-soaked flowers on the plants or trees. Surrounding leaves progressively turn brown with black blotches, then curl and shrivel. Smaller twigs will begin to wilt from the tip, turn black and curl into a hook shape. Then, larger branches develop dark cankers that girdle the branches, which then die.
Trees and shrubs can be infected by the bacteria through existing cankers or bud scars. The bacteria then over-winters and becomes active in spring. An ooze forms which attracts insects that then spread the bacteria through the flowers of the plant. Rainfall and irrigation water droplets can also spread the bacteria which can then infect leaves and young growth.
So, what's to be done about this disease? Once the disease has been identified, it's important to perform sanitation pruning once temperatures reach about 90 Degrees F and the spread is slowed. Infected branches must be cut off 8 to 12 inches below the visible canker or infection zone. Pruning tools should be properly sanitized between each cut to prevent further spread of the disease. While it's not always possible to save every tree that is heavily infected with Fireblight, sanitation pruning can often help preserve many trees.
Posted: November 23, 2015