The Time is Right to Start Thinking About Treating for Fire Blight

Fire Blight

In many areas of the country, the weather may be blustery and cold. It’s hard to believe that spring is right around the corner, but it is – and that means it’s time to plan treatment for Fire Blight.

What is Fire Blight?

Fire Blight is the most damaging bacterial disease that affects shrubs and trees in the Rosaceae family during warm spring weather combined with rains or heavy dews. This disease is most often found in pear, apple, loquat, and crabapple trees and has become a nuisance to homeowners and commercial landscape managers. Flower infections can be introduced by bees and other insects from infected wood cankers that ooze bacterial substance in the spring. Trees infected with the Fire Blight bacterium Erwinia amylovora often have extensive limb cankers and dieback with a characteristic “Shepherd’s Crook” appearance at the tips of the shoots.


The first sign of a Fire Blight infection is early death of flowers, then death of the green shoots immediately adjacent to the flower petiole. The bacterium moves into the wood of twigs and lateral branches, which express black cankers and can turn completely black. By further spreading of the bacterium with rain splashes and insects to other flowers and shoots, symptoms will often appear scattered throughout the canopy. However, if the weather conditions are most favorable for disease progression and spreading, the whole canopy can be severely affected with a burned appearance, lending itself to the name Fire Blight.

How to Protect Your Trees

Planning ahead is essential. Early spring injections of Arbor-OTC® just as buds break is the most optimum time to treat susceptible trees.

Treatment timing is key. With spring rapidly approaching, now is the time to protect and treat. As late spring and summer temperatures begin to climb, the bacteria will go dormant when water in the soil is scarce and when temperatures are around 85-90°F. It’s essential to get to the source before this happens.

For more information and research on Fire Blight and Arbor-OTC, please browse our website. To begin discussing treatment options, contact a Regional Technical Manager or an Arborjet recommended treecare service provider near you.