Factors which enhance the risk of fireblight

• Untreated inoculum. If fireblight infection is not noticed or is ignored in the orchard or apple or pear nursery or on nearby hawthorn or ornamental hosts especially cotoneaster and pyracantha infection risk is greatly increased.
• Warm periods during primary apple blossom.
• Late flowers or secondary blossom on apples.
• Overlap of flowering between pears, apples, hawthorns and/or ornamental hosts.
• Inoculum can be spread by bees and other insects visiting flowers.
• Shoot and fruit blight. Damaging storms with wind-blown rain at times of rapid shoot growth can spread the disease as inoculum may be spread by wind-blown rain from diseased to healthy trees.
• Hail storms favour fruit blight.
• Complacency, by ignoring fireblight as a potentially important disease of apples.