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Fire Blight is a bacterial infection caused by the Erwinia amylovora bacteria. It is most prevalent on the following trees: apple, pear, hawthorn, cotoneaster, firethorn and mountain ash. The bacteria overwinters on or under infected bark and in the early spring begins to ooze out. During the damp spring period the disease is spread by rain, improper pruning and insects such as honeybees which transmit the bacterial infection from blossom to blossom. Trees are very vulnerable to Fire Blight infections immediately after heavy rains or hail storms where leaf tissue is exposed from rips and physical damage.
Once the blossom or leaf is infected, the bacteria spreads quickly throughout new tender growth, but slows as it reaches more mature woody growth. As the branch is infected, the leaves begin to brown and blacken and appear almost burnt, hence the name fire blight.
As the disease advances and the fungus reproduces, it begins to block the tree’s vascular system and causes branch die back or cankers to develop as the bacteria expands and “bursts out” of the tree’s bark.
If left untreated, Fire Blight will gradually infect the entire tree, block the tree’s vascular system and kill it.
To control or prevent fire blight, in the early spring, before bud break, spray the tree with Liquid Copper Fungicide to reduce or eliminate any bacterial spores that are overwintering on the bark.
Shortly after bud break, spray the tree with Agri-Fos Systemic Fungicide, ensuring thorough coverage. To improve the binding and penetration for the fungicide applied it with Nature's Own Spray Helper or Pentra-Bark (call for details). Repeat the spray at one to two month intervals, more frequently in high disease situations.
Prune out infected branches. The point of pruning must be 12 to 16 inches beyond the last visible signs of the disease on the branch. It is critical that the pruning tools be sanitized after each branch is pruned, so as to prevent spreading the disease form branch to branch.