The dangers of honey fungus

Honey Fungus The wettest winter on record, followed by the wettest summer for over 50 years has led to a major spread in the disease of Honey Fungus (Armillaria). As the roots become weakened the tree or shrub will become very susceptible to high winds which can be a major hazard with larger trees.

Although there are 7 species considered to be under the Armillaria genus, the most aggressive are Armillaria mellea and Armillaria.ostoyae, which will attack even healthy trees and woody shrubs. The other 5 species ‘feed’ from dead stumps and roots, which is where they live until their energy source starts to deplete. The organism then spreads in search for new nourishment and there would be considerably more dead trees laying around if this fungus did not help to decompose fallen trees and roots.

The problem with Honey Fungus is that it spreads quickly and all the trees in a garden or indeed a whole forest can be destroyed, almost before the problem has been identified and is perhaps the most dreaded of all diseases in the gardening industry. It has been proven a single fungus can spread in an area as large as 37 acres and infect all the trees in its path. The growth is underground in the main at the rate of approximately 1 metre each year, although it is thought that in warm, humid conditions it might travel much further.

How to identify Honey Fungus?
Affected trees may die quite suddenly, often without any obvious warning signs. Often, the first time this disease becomes apparent is when new leaves do not appear in spring on deciduous trees and shrubs Trees and plants die . . . sometimes because it’s the end of their life-cycle or for a whole host of other reasons so gardeners should not panic if they see toadstools in Autumn . . . it is not necessarily Honey Fungus! However, there are ‘signs’ to watch out for;

Clusters of a yellowish- orange or honey coloured toadstools around the base of a diseased tree or tree stump
Sometimes a tree can ‘leak’ at its base with a gooey resin
If you peel back a small area of floppy bark you may find White Mycelium (fungus roots) under it
A wet or ‘slimy’ tree roots that may also smell

The toadstools usually appear between late summer and Autumn, but do vary each year (July – December) and does slightly depend in what part of the country you live in. Rhizomorphs are not considered to be a helpful diagnostic feature.

How does Honey Fungus spread?
There are two ways that Honey Fungus spreads. Spores do spread in the wind, but the most common method of expanse is underground by rhizomorphs (fungal roots). Rhizomorphs are black boot-lace like threads that push through soil. These rhizomorphs spread outward from a colonised root or tree stump and have infective tips, which can then invade the bark of other trees and roots below ground level to infect a new host. Spores spread by the wind land on wounds of trees or fresh cuts and there is little or nothing that can be done to prevent it. When you cut tree branches, you create wounds that can act as open doors for disease. To prevent this, trees naturally seal off wounds after pruning, though they do not actually heal them. Instead, fresh tissue grows to cover the wounds, protecting them from decay and disease. However, many gardeners used to apply wound dressings such as latex paint mixed with water to protect trees after pruning; current research has revealed that this is not beneficial. Wound dressings do not prevent decay, disease or insect infestations as once believed. Indeed, they may even prevent the wood from drying, which can spark fungal growth. .

How to prevent Honey Fungus?
Unfortunately, there is nothing to be done to totally prevent Honey Fungus gaining a foothold in your garden or grounds. If your trees and plants are healthy they are less susceptible to becoming diseased, but even the most healthy specimen can be attacked and destroyed. If the specimens in your garden are stressed in any way, then they become very susceptible to attack If you specimens are strong and healthy there is a greater reduced risk of being attacked so good gardening practice is recommended this year more than any other. Any autumn/winter feeding and protection you can carry out may help to ward-off any potential attack. In spring, get an early feed down as early as possible to give any likely victims a little boost.

What needs to be done if Honey Fungus is detected?
There is only one remedy! The affected stumps, trees and plants must be removed and the debris created should be taken away or burnt in a very hot fire on-site (although not ideal). Any stumps and roots remaining should be ground out to a minimum depth of 8 inches with a stump grinder or in seriously affected areas the stumps may be dug out using a mini digger.

 

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