When a shoot on apple or pear wilts overnight, turns black and looks as if a flame had scorched it, caution is due. That is possibly fire blight, the most feared disease of pome fruit. Unlike with a fungus, here fast, correct action counts for more than any home remedy.
This article is the detail edition to the overview in Recognising fruit tree diseases. It shows you how to recognise fire blight and what to do on suspicion, because here special rules apply.
How to recognise fire blight
The damage picture is dramatic and usually clear. Blossoms, leaves and young shoots wilt suddenly, turn brown to black and look as if burnt. Typically the wilted leaves stay hanging on the twig instead of dropping. The shoot tips curl characteristically downward, like a shepherd's crook.
Another sure sign appears in warm, humid weather: at affected spots, milky-white to amber ooze droplets well out, the bacterial slime. The pathogen, the bacterium Erwinia amylovora, spreads at breakneck speed via rain, insects and above all pruning tools.
What you must do, and what not
Do not prune yourself
The first and most important step is to stay calm and not prune in a panic. Every improper cut spreads the bacteria in the tree and into the neighbouring garden.
Report the suspicion
Report the suspicion to the plant-protection authority. Experts confirm the diagnosis and set how to proceed, from cutting back to, in the worst case, felling the tree.
Mind tools and hygiene
If cutting is done after all, it goes far into the healthy wood, and the tools are thoroughly disinfected after each cut. The affected material is disposed of by the rules, usually burnt.
Prevent through restraint
Do not feed too heavily, because soft, lush foliage is especially susceptible. Near orchards, do without highly susceptible ornamental shrubs like hawthorn or cotoneaster.
Do not cut, report. With fire blight, fast, correct action by the rules decides, not your own busywork.
The core rule for fire blight
Frequently asked questions
How do I reliably recognise fire blight?
By suddenly wilting, brown-black shoots that look burnt and curl at the tip like a shepherd's crook. The wilted leaves stay hanging. In warm, humid weather milky ooze droplets emerge. This combination is typical.
Why is fire blight notifiable?
Because it is highly contagious and can destroy whole orchards and wild stands. So it does not spread, the authorities must know of every suspicion and act in a coordinated way. That is why reporting is mandatory.
Can I save the tree myself?
Only in consultation with the experts. A light early attack can sometimes be stopped by generous cutting back into healthy wood, with strict tool hygiene. With heavy attack, often only felling remains, to protect the surroundings.
Which trees and shrubs are affected?
Only pome fruit and related ornamental shrubs: apple, pear, quince, medlar, plus hawthorn, cotoneaster, firethorn and rowan. Stone and soft fruit and vegetables are not affected.
How can I prevent it?
With moderate feeding, because soft foliage is more susceptible, and by keeping highly susceptible ornamental shrubs away from fruit trees. Fire blight cannot be prevented entirely, but you can lower the risk and spot it early.
