Fire Blight is a bacterial infection caused by Erwinia amylovora. It is most prevalent on apple, pear, hawthorn, cotoneaster, firethorn, and mountain ash trees. The bacteria overwinter on or under infected bark and begin to ooze out in early spring. During damp spring conditions, the disease spreads through rain, improper pruning, and insects such as honeybees, which transmit the bacteria from blossom to blossom. Trees are particularly vulnerable to Fire Blight infections immediately after heavy rains or hail storms, when leaf tissue is exposed to rips and physical damage.

Once a blossom or leaf is infected, the bacteria spreads rapidly through new tender growth but slows as it reaches mature woody tissue. Infected branches show leaves that brown and blacken, appearing almost burnt—hence the name Fire Blight.

As the disease progresses, it blocks the tree’s vascular system, causing branch dieback or cankers as the bacteria expands and “bursts out” of the bark. If left untreated, Fire Blight can gradually infect the entire tree, block the vascular system, and eventually kill the tree.

Recommended Steps to Control Fire Blight:

• In early spring, before bud break, spray the tree with Liquid Copper Fungicide to reduce or eliminate overwintering bacterial spores on the bark.

• Shortly after bud break, spray the tree with Agri-Fos Systemic Fungicide, ensuring thorough coverage. For better binding and penetration, apply it with Nature's Own Spray Helper or Pentra-Bark (for details, contact supplier). Repeat sprays at 1 to 2 month intervals, more frequently in high-disease situations.

• Prune out infected branches. Make cuts 12 to 16 inches beyond the last visible signs of infection.

• Sanitize pruning tools after each cut to prevent spreading the disease from branch to branch.