Fire blight

Fire blight is a destructive plant disease caused by the bacterium Erwinia amylovora. Recognized globally as a severe threat to pomology, this pathogen affects a wide range of plants in the Rosaceae family, leading to rapid tissue death and significant economic losses for commercial fruit orchards.

The host range is broad, but the most economically significant victims include domestic apple, common pear, and common raspberry. The bacterium colonizes the xylem of the host plant, disrupting water and nutrient transport, which causes the characteristic wilting and scorching appearance that gives the disease its common name.

Key symptoms include the sudden wilting and blackening of blossoms and young shoots, often curling into a distinct shepherd's crook shape. During periods of high humidity, infected tissues may ooze a bacterial slime (exudate) which serves as a major reservoir for spreading the infection to healthy parts of the plant or neighboring trees.

The spread of Erwinia amylovora is highly dependent on environmental conditions, particularly warm temperatures and rainfall during the bloom period. The pathogen is disseminated by pollinating insects, wind-blown rain, and human activities such as pruning, where non-disinfected tools effectively transmit bacteria from infected to healthy trees.

Integrated management is essential for control. Strategies include:

• Removal and destruction of infected limbs during the dormant season.
• Disinfecting pruning tools with 70% alcohol or bleach between each cut.
• Applying copper-based bactericides during bloom.
• Planting resistant or tolerant cultivars to minimize orchard susceptibility.