DISEASE

NAME
Fireblight
Erwinia amylovora

Description
Bacterial problem affecting flowers, stems and leaves. Not found in Australia.

Symptoms
The spring flower buds and new growth are attacked. Buds are first attacked become watery and turn black, it then moves into the twigs and branches causing them shrivel and blacken with the ends often curling, (Shepard`s Hook) giving it a burnt appearance.
In heavily infested plants cankers may occur on the branches with discoloured oozing patches. The translucent amber or reddish ooze contains masses of bacteria. Heavy persistent infections can kill the host.



Source and Dispersal
The Fire Blight bacteria are dispersed by rain splashes; birds, insects or animals that come in contact with an infected plant. Infected gardening tools or watering may also spread the bacteria. It overwinters in dead branches or in holdover cankers.

Favoured Conditions
Infection predominately occurs in late spring or early summer when the bacteria emerge from their dormant period and amber coloured oozing from the cankers is most pronounced. It prefers humid wet conditions with the temperature above 20şC.
     
Affected Plants
There is a wide range of plants affected these include rosaceous plants apple, flowering crab, pear, Firethorn, Hawthorn, Photinia, Cotoneaster, Chaenomelesspecies and Mountain Ash (Sorbus aucuparia).

Non-chemical Control
There is no cure for fire blight, remove infected stems and branches and destroy. When pruning cut about 200mm from the infected area then destroy removed material and never prune during wet weather. This bacterium is easily transmitted and all tools that come in contact with the infected plant should be disinfected. Remove all fallen plant material such as leaf litter and fallen twigs.

Chemical Control
There are a variety of bactericides have been developed to fight fire blight, many of the most common containing streptomycin sulphate.