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Bacteria, GRACILICUTES, EUBACTERIALES, ENTEROBACTERIACEAE .

Crops attacked: apple, .

Fire blight

Identification, Description, Biology, Epidemiology, Treatement, Possible misleading, Images

[R]Description
Fire blight is one of the most devastating diseases affecting the Rosaceae.
The most severe symptoms are in Pear.
During flowering the blossoms and young shoots turn black, dry out on the tree and curl at the top.
The leaves of the affected parts look as if burnt by fire.
The disease develops towards the base of the twigs.
A slime may ooze from young shoots whose wood is still soft.
In autumn the main branches are also likely to be affected which causes drying out of their twigs and leaves.
Cankers form under the bark which swells, cracks, oozes and shows a reddish discoloration.

[R]Biology
The bacteria overwinter in the cankers.
The drops of gummy exudate are the main source of inoculum in spring.
The bacterium enters through flowers, through wounds on shoots caused by rain stones and through such natural ways in as stomatas and lenticels.
The disease spreads rapidly and steadily under the bark towards the base of the trunk causing death of the tree after a few months in less resistant cultivars.

[R]Epidemiology
Dissemination by rains, and handling of infected scions.
Outbreaks occur under relatively high temperature.
The optimum temperature is 18 °C. Severe contamination can occur at 21 - 30 °C. in sunny days when aphids are very active.
The second flowering of pear under more favourable temperature conditions partially explains the high susceptibility of this host.
Humid or windy weather facilitates the dispersal of the exudate which can directly infect the branches.

[R]Treatement
If the disease is detected in an area in which it has never been reported before, inform the local authorities right away and apply the advised control.
Keep susceptible plants in new crops under close observation.
Use well-balanced fertilizers.
Avoid irrigating in excess.
Eliminate symptoms, burn heavily infected plants.
Disinfect implements.

[R]Possible misleading
Possible confusion with symptoms caused by cephe.

[R] Images

1. Erwinia amylovora , Fire blight (BASF)
   Fire blight of fruit-trees A branch of apple infected by fire blight.
   
2. Erwinia amylovora , Fire blight (BASF)
   Fire blight of fruit-trees Young shoot infected by fire blight.
   
3. Erwinia amylovora , Fire blight (PAULIN J-P., INRA)
   Fire blight of fruit-trees Blight of a pear shoot infected by Erwinia amylovora .
   
4. Erwinia amylovora , Fire blight (BASF)
   Fire blight of fruit-trees Young pears infected by fire blight.
   
5. Erwinia amylovora , Fire blight (BASF)
   Fire blight of fruit-trees Bacterial exsudate on apple.
   
6. Erwinia amylovora , Fire blight (PAULIN J-P., INRA)
   Fire blight of fruit-trees Pruning and cleansing of main branch and trunk in order to fight fire blight.
   
7. Erwinia amylovora , Fire-blight (LEMOINE J., INRA)
   Fire blight of fruit-trees Decline and withering of a quince-tree due to fire-blight.
   

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