British gardeners have been warned to be on the lookout for a fast–spreading fungus that is not as delightful as it sounds.
Honey fungus, also known as ‘golden mushroom’ or Armillaria mellea, is a common species that infects and kills trees and woody shrubs.
Populations of the pathogenic species have increased by 200 per cent in Britain in the past year, according to iNaturalist.
This has largely been caused by a particularly hot summer followed by a damp autumn – weather extremes that have been linked to climate change.
Beloved garden plants most frequently attacked by honey fungus include birch, cedar, privet, willow, lilac, weigela and cotoneaster.
Meanwhile edible varieties found in allotments also at risk include strawberry and potato.
‘Honey fungus infection can be deadly for plants,’ say experts at the the Royal Horticultural Society (RHS).
‘If trees are affected, cutting them down to stumps will not remove the source of infection as the fungus can gain nutrients from dead wood and roots for many years.’
This disease might sound delicious but it is actually a virulent fungal infection that can kill the hardiest of plants. Pictured, honey fungus (Armillaria mellea) in Whitewebbs Wood, Enfield, UK
According to the RHS, honey fungus is ‘the most destructive fungal disease in UK gardens’ and has topped its list of the top 10 most common diseases since the 1990s.
It can be identified by its yellow–brown to honey coloured toadstools, which are darker near the centre.
Directly underneath are the white or cream–colored gills, which release a dusting of white ‘frosting’ – actually their white spores.
‘Honey fungus mushrooms appear in the autumn months,’ said Dr Jassy Drakulic, senior plant pathologist at the RHS.
‘When fresh, these look like clumps of buff or honey–coloured mushrooms, often with dark centres and white gills and spores underneath.’
Below the ground, honey fungus attacks and kills the roots of hardy ‘perennial’ plants that live for multiple years and then decay the dead wood.
Honey fungus form a network of black root–like structures called rhizomorphs, also known as boot lace, which helps them spread and attack new hosts.
‘They form these physically tough conduits for transport and mass movement within a network – they’re like super–highways,’ Dr Daniel Henk, a mycologist at the University of Bath, told the Guardian.
Symptoms of honey fungus include pale leaves, dieback, early autumn colour and a cracking, bleeding trunk
Honey fungus form a network of black root–like structures called rhizomorphs, also known as boot lace, which helps them invade tree roots and bark
But the most common sign of infection is a thin white layer of mycelium – the fungal tissue which forms beneath the bark at the plant’s base.
To find this, peel back the bark right right at the bottom where the soil is. Between the bark and the wood of the plant, you will find a flat, whiteish sheet of mycelium with a strong mushroom smell.
Other indications that plants are affected include ‘dieback’ (the gradual death of branches and leaves), failure to flower, pale foliage and cracked bark that is ‘bleeding’ with fluid.
Unfortunately, there is no known chemical treatment for honey fungus, so the best response is to dig up the affected plant entirely and burn it.
‘Never compost disease material – dispose of it by burning or in landfill,’ added Dr Drakulic.
Healthy plants are less likely to succumb to honey fungus, so the best defence for gardeners is ‘maintaining general good health’ in at–risk plants.
‘Ensure they have sufficient access to water and nutrients, don’t over–prune them, don’t bury them too deeply,’ said the RHS expert.
Another good tip to boost plant health is applying a layer of mulch – a mix of organic residue typically comprised of leaves, compost and bark – in a donut shape around the tree.
Honey fungus infects the roots of trees and digests them, leading to the plant’s death. This has been the RHS’s most common disease for 28 years
According to WildFood UK, honey fungus is actually edible for humans, as long as it has been cooked.
However, it can give some people ‘gastric upsets’ so it should be ‘tried in small amounts the first time it is eaten’.
Bear in mind though that it is very dangerous to pick up and eat a mushroom growing from the ground, as it might be very poisonous.
Even if you think a mushroom is safe, you may be misidentifying it as many species of various toxicities look alike.
You could be picking up the death cap mushroom, the most dangerous mushroom in the UK, which contains enough toxin to kill an adult.
Other dangerous UK species include the deadly webcap, the fool’s conecap and the destroying angel.
What are the dangers of eating death cap mushrooms?
Amanita Phalloides, commonly known as the death cap, is a deadly poisonous fungus. A few mouthfuls of the death cap mushroom can kill.
They often grow near established oak trees, and are found when there is warm, wet weather.
The fungi stand out due to the pale green colouring of their caps, a bulbous end at the foot of the stalk and an annulus – a ring-like collar – at the top.
Amanita Phalloides, or death cap, often grow near oak trees and are highly toxic
The death cap is native to Europe, where it is widespread in Britain and Ireland. It is also commonly found in northern Africa and in many parts of Asia, including the forests of Iran.
People are warned against picking or consuming wild death cap mushrooms. Cooking the fungi does not remove the death cap’s deadliest toxins, called amatoxins.
Looking like a delicious white button mushroom when young, the death cap’s appearance is far from deadly. It can be extremely difficult even for experienced collectors to distinguish them from an edible mushroom.
Symptoms of death cap mushroom poisoning generally occur six to 24 hours or more after ingestion of the mushrooms. They include stomach pains, nausea, vomiting and diarrhoea.
The symptoms may subside after one to two days, giving a false impression of recovery. However, by this stage the toxin would have already caused serious liver damage and may result in death.
