Fire Blight

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Changed on: 09.05.2016
Schadsymptome des Feuerbrandes an einem Apfelbaum - ein befallener Ast hängt braun herunter.

Fire blight is a highly infectious and difficult to control disease found in various fruit and ornamental trees of the botanical Rosaceae family. The pathogen is the Erwinia amylovora bacterium. This disease poses a threat to both commercial and landscape-shaping fruit cultivation, tree nurseries, home gardens and public parks.

Plants affected might die within a short period.

Fire blight is considered to have originated in the USA, where reports of this disease were already recorded 200 years ago. In Europe, the first reported cases of fire blight were made in southern England in 1957 and evidence of the disease has been detected in all European countries since that date.

Fire Blight is a quarantine disease; any outbreak must be reported to the authorities.

• Current fire blight situation

Schadsymptome des Feuerbrandes an einem Apfelbaum - ein befallener Ast hängt braun herunter.

Fire blight is a highly infectious and difficult to control disease found in various fruit and ornamental trees of the botanical Rosaceae family. The pathogen is the Erwinia amylovora bacterium. This disease poses a threat to both commercial and landscape-shaping fruit cultivation, tree nurseries, home gardens and public parks.

Plants affected might die within a short period.

Fire blight is considered to have originated in the USA, where reports of this disease were already recorded 200 years ago. In Europe, the first reported cases of fire blight were made in southern England in 1957 and evidence of the disease has been detected in all European countries since that date.

Fire Blight is a quarantine disease; any outbreak must be reported to the authorities.

• Current fire blight situation

Symptoms

First symptoms

caption
Bacterial slime oozing from a shoot
Feuerbrand Symptom - Austretender Bakterienschleim an einem Trieb
caption
first symptoms on the leaf of an apple tree
Feuerbrand Symptome - Erste Symptome am Blatt eines Apfelbaumes

The leaves and flowers of plants affected will suddenly wilt and turn brown and black. Infected shoots appear pale green at first and will desiccate while turning brown to black in colour. The tips of the shoots will often appear hook-shaped, as a result of water loss. Droplets of sticky, white  bacteria slime will emerge from the affected areas of the plant in wet weather, turning brown later.

Further progression

caption
Infected shoot, triggered by a flower infection
Fire blight symptom - Infected shoot caused by a blossom infection
caption
hook-shaped shoot
Feuerbrand Symptome - Hakenförmig gekrümmter Trieb

The wood under the bark of recently affected trees will show a red-brownish colour and is permeated by sticky bacterial slime, oozing through the bark.

The bacteria will stop spreading at the end of the vegetation period. Bark areas that are affected will cave in, forming a clear border between diseased and healthy tissue. Dead leaves and shrivelled fruit will remain on the branches that look burnt during the winter. The beginning of new infections in spring are bacterial exsudates emerging from cancer-like blight spots on the perennial wood.

Transmission

caption
Mummified fruit of a pear
Feuerbrand Symptome - Fruchtmumie einer Birne

The fire blight pathogen is transmitted to the shoots of susceptible hosts by finding its way into the plant via natural openings (pores, stomata) or wounds. The pathogen spreads faster in younger shoots than in older ones within the host. The first signs of dying off are visible four days after infection at the earliest. A young pear tree can die as rapidly as within two to three weeks.

Diagnosis

AGES carries out lab tests for the monitoring on fire blight infestations on host plants, as required by the EU, coordinates appropriate activities and conducts – partly in cooperation with provincial governments and professional associations – free-range trials on alternative control methods (including the use of bees).

Contact

Institute for Sustainable Plant Production
Phone: +43(0)5 0555 34200
Spargelfeldstraße 191
1220 Wien



Institute for Sustainable Plant Production
Phone: +43(0)5 0555 34200
Spargelfeldstraße 191
1220 Wien



    Feuerbrand_Diagnoseschema_2010_03.pdf (496 K)
    Fire blight diagnostic diagram 2010
    download file  | open PDF

    Probenbegleitschein_Private_Feuerbrandproben_03.pdf (79 K)
    Sample supplementary sheet for submitting private fire blight samples
    download file  | open PDF

Control

Control

Prophylaxis

  • Reduce inoculum as much as possible before flowering 
  • Carry out regular check-ups in dry weather periods! 
  • Avoid treatment with pesticides for damaging animal or fungal organisms during periods of acute fire blight infection risk 
  • Avoid overhead irrigation and mechanical thinning out during periods of high infection risk
  • Late blooming trees and nurseries with trees that bloom late have a higher risk of infection

Restoring

  • Clear or prune generously as quickly as possible (ideally within a few days after finding out about the fire blight infestation)
  • Seal / cauterise larger cuts 
  • Burn infected plants or plant parts that were cleared or cut off immediately 
  • Do not leave plant material lying around! 
  • Avoid doing damage to healthy trees! 
  • Postpone maintenance when there is too much bacterial slime 
  • In cases of heavy infestation, do not use mechanical means, such as cutting (high risk of spreading the bacteria); always disinfect or sterilise (using heat) cutting tools

Specific dangers in the spreading of the disease

  • Rain, hail, wind (cause small wounds) 
  • Tools, shoes, hands, clothes, tires of machines

It is important to know whether the material comes from a fire blight free region to avoid infection and the spread of the disease. There are very strict requirements for the delivery of plants that can serve as hosts for fire blight in protected areas.

The import and export of plants that can serve as hosts for fire blight is regulated in the Federal Act on measures for the protection against the import and export of damaging organisms for plants and plant products (Austrian Plant Protection Act 2011, Fed. Law Gazette I No. 10/2011).

AGES explanations concerning the setting up of fire blight puffer zones (pdf)

Use of pesticides in fire blight control


 

 


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