Fire blight in apple trees: causes and treatment

How do I know if the apple tree has fire blight?

Since the main route of infection the blossoms are, these will initially withered and discolour later dark brown. The bacterium migrates via the flower stalk into shoots, branches and the trunk. You can finally recognize advanced fire blight by the almost black, cane-like curved shoot tips.

Another feature is the sticky droplets of bacterial slime that emerge on the branches when the weather is warm and humid. These are whitish or colored like light amber. Affected parts of the bark sink in and there is a clear boundary line between diseased and healthy tissue.

Why is the damage from fire blight so massive?

The bacterium Erwinia amylovora migrates through the meridians and clogs them with excretions. Due to the reduced water transport the leaf veins first turn brown, later the fresh as well as the already lignified shoots wither and their tips curve downwards like a hook.

Since the disease usually begins on the flowers, in spring the pollinating bees and bumblebees to the main distributor. The escaping bacterial slime is very dangerous for healthy plants, as it is spread over large areas by raindrops, wind, insects and birds.

How can I fight fire blight in apples?

Unfortunately there is currently no approved preparations for the home garden, with which fire blight could be cured. Therefore, check the apple tree for the first signs of the disease at the beginning of the flowering period. If you discover an infestation, you should proceed as follows:

• Cut back the affected shoots deep into the healthy wood.
• Disinfect all tools thoroughly afterwards.
• If permitted, burn diseased plant parts directly or dispose of them with household waste.
• Heavily infested apple trees must be uprooted.

How can I prevent fire blight on apple trees?

The same applies to fire blight: The best prevention is the planting from hardy varieties. These are for example:

• Pilot,
• bell apple,
• Jacob Fischer,
• beautiful from Boskoop,
• Retina.

In addition, you should combat all leaf-sucking insects such as aphids with ecological measures, because if the animals come into contact with the bacterial slime, they transmit the disease to others plant parts.

Is fire blight a notifiable plant disease?

Fireblight is one reportable quarantine disease. You must therefore report diseased trees to the responsible municipality, the district office or the state institute for agriculture. The authority will take samples from the infested apple tree, have them examined in the laboratory and coordinate with you how to proceed.