Basic Info:
Fire blight is one of the most destructive diseases of fruit trees in North America. It occurs sporadically and unpredictably and occasionally reaches epidemic levels. In the spring, infected blossoms suddenly wilt and turn brown. Later, twigs and leaves also turn brown and appear to be scorched by fire, hence the common name. The affected leaves usually remain on the tree well into the winter. Young infected fruits become watery or oily in appearance and exude droplets of clear, milky, or amber colored ooze. They later become leathery and turn brown, dark brown, or black, depending on the species. The shriveled fruit usually remains attached to the tree. The bark of branches and stems becomes reddish and water-soaked at the advancing edge of the infection and later cracks and turns black. The shriveled, leathery infected fruit usually remains attached to the tree. Fire blight is caused by a bacterium (Erwinia amylovora [Burrill] Windslow et al.) that may enter the tree through the blossoms, leaves, or stem wounds. Usually the disease is spread by bacteria that overwinter in holdover cankers in the main stem and branches or infected twigs. In the spring, just when the blossoms begin to open, the cankers exude drops of bacterial ooze that are disseminated to the blossoms and young leaves principally by rain, heavy dew, or windblown mist. Fire blight may also be spread by pollinating insects such as bees; sucking, chewing, or boring insects; and unsanitary pruning tools. Warm temperatures (24-28 °C) and high humidity are the optimal conditions for infection and disease development.
What We Recommend:
1) Remove the host of the disease completely from the area/site.
2) Prune and destroy diseased twigs and branches is the only effective method of control. They should be cut at least 30 cm below the last sign of infected bark.
Tree Effected By Fire Blight: American Mountain Ash, Apple, Chokecherry, Common Pear, Crabapple trees, Hawthorns, Saskatoon.
Government Informational Source Link:
https://tidcf.nrcan.gc.ca/en/diseases-caused-by-pathogens/factsheet/176
