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Erwinia amylovora

Fireblight, Fire Blight

by AlanGardenMaster. All rights reserved

Fireblight is an incredibly devastating disease that is apparent worldwide. In many parts of the world, there are quarantine laws that try to prevent its spread. It affects woody plants that are part of the Rose family and especially affects those that flower during the summer. Fireblight has been known to wipe out entire orchards in one growing season. Part of its infectiousness is due to the number of vectors for the disease as it can be transmitted from any creature that touches it including pollinators, birds, pests and tools. The rose family is also a largely used family for fruits grown and hedging in the UK which means that there are plenty of possible hosts for infection. In the UK, if the disease is found then all susceptible plants within 100 square meters of the specimen must be destroyed and burned immediately.
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Dieback of blossoms and leaves on branches looking as though they have been scorched by fire (Hence the name Fireblight). The dead material has a thick black exudate that is full of the bacteria. Affects plants almost exclusively in the Rosaceae family.

Growth factors

Will affect Summer blossoming plants a lot more than early spring blossom. Most infectious during hot, wet weather. Over-fertilization and over watering can increase the risk of infection.


Dieback of blossom and leaves
Thick black exudate on dead leaves.
A slimy white liquid oozing from plants during wet weather
Bark fades to a red-brown colour

Biological treatment

Report any outbreak to DEFRA. The 'Saphyr' cultivar range of Pyracantha is resistant. However, this makes little difference if there is a large outbreak.

Chemical treatment

Report any outbreak to DEFRA. There are no chemical treatments available.


The bacteria infect the plant through stomata and start killing the leaves. They multiply and produce a thick black exudate which sticks to vectors or washes off in rain to spread the bacteria. Bacteria replicate through binary fission which means the number of bacteria doubles every 20 minutes.


Quarantines are in place to reduce the risk of infection. Not planting hedging that belongs to the rose family around orchards.

Affected plants


Pyrus spp.


Malus spp.

A red rose on a Rosa plant


Rosa spp.


Eriobotrya japonica

Malus sylvestris flower

Crab Apple

Malus sylvestris


Cydonia spp.

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