Fire Blight

Fire Blight typically affects trees in the Rosaceae family (Flowering Pear, Crabapple, Hawthorne, etc.). It causes discoloration, die back and death. While there is no cure, early detection, prevention and proper pruning can help reduce the spread.

What is Fire Blight?

Fire Blight is the most damaging bacterial disease affecting trees and shrubs. It is most often found in Apple, Pear and Crabapple tree (members of the Rosaceae family). It is caused by a bacteria (Erwinia amylovora) that is spread when sap containing the bacterium oozes from dead cankers during rainy spring weather and when it is blown to nearby trees or drips onto branches below. Bees will also be attracted to the sap and spread the bacteria to the flowers.

You will see small black cankers on the stems of infected branches and the leaves will turn brown and wilt on the tree. It can eventually causes fruit loss, destruction of limbs, canopy loss and death of the tree.

Warm and moist conditions are ideal for this disease to spread. Trees are especially at risk if a freeze occurs after they have begun to bloom. Once the disease is present it may harbor in the tree indefinitely. There is no cure.

What are the symptoms of Fire Blight?

– Watery tan colored sap that forms as the bacteria is spreading

– Blackened and dying leaves

– Wilted shoots

– Cankers on twigs and branches

– A scorched or burnt appearance to leaves and canopy

Leaf Die Back
Oozing Sap
“Burnt” Canopy
Photos: Purdue Agricultural Communication photo/Janna Beckerman

How is Fire Blight treated?

The best treatment for Fire Blight is to apply a trunk injection of Arbor-OTC systemic antibiotic in the spring prior to flowering. Pruning out deadwood when trees are dormant is also helpful.

– Dormant pruning of deadwood for general health of tree and prevention.

– Pruning of infected trees to remove diseased areas

– Antibiotic trunk injections to help control bacteria, although this will not cure the disease

– Soil surfactant to encourage deeper absorption of nutrients

Removal of infected trees if the disease has affected the main stem and the tree cannot be saved and should be removed to prevent spread

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