Honey Fungus

Most people who spend some time gardening have probably heard of Honey Fungus and if really unlucky may actually have had to deal with it. For anyone unfamiliar with the disease and needing some help diagnosing and dealing with it, hopefully this post will help.

Honey fungus


Honey Fungus is the name given to the Armillaria species of fungi, a parasitic group which can affect a wide range of trees and woody plants. It causes a white rot of the roots and heartwood and often leads to the sudden death of its host. Wind throw also occurs when decay progresses rapidly within the roots.

Honey Fungus disease

Normally the easiest way of diagnosing the disease is by its fungal fruiting bodies. These manifest as large clumps of toadstools around the base of the tree and sometimes up the trunk. The toadstools are yellow-brown in colour the stalk of which has a distinct whitish collar beneath the cap. These only form in the autumn so additional indicators are required at other times of the year such as the sudden death of other plants nearby or stem bleeds on the suspected host. One of the best indicators to confirm honey fungus infection is the presence of white mycelium beneath bark. This is commonly found when removing dead bark and has a distinctive 'mushroomy' smell.

Honey fungus spreads through the ground via structures known as rhizomorphs. These are like black bootlaces which extend out from decaying wood and roots of infected trees. The tips of these 'bootlaces' are capable of infecting healthy tree and plant roots leading to the death of the internal wood structures and eventual decay.

So what can you do if you suspect Honey Fungus in your garden or on your land?

Well, there's no 'cure' for Honey Fungus. Unfortunately if your plant is infected than it's probably only a matter of time before the inevitable and it dies. The speed of death will vary depending on the virulence of the particular Armillaria and the vitality and vigour of the infected tree and its ability to hold off death. 

honey fungus kills trees

To prevent the spread of Honey Fungus from plant to plant the infected tree should be removed and all infected material dug out. If the tree is part of a closely planted hedgero then the adjacent plants should be removed as a precaution. If all material is removed replanting should be possible. If this is not practicable then digging out as much infected material as possible and replacing with a resistant plant should avoid reinfection. Insertion of a physical barrier such as plastic sheeting between the source of infection and any new plants may work providing it's well installed and there are no defects in the sheeting.

If you believe you have a plant infected with honey fungus and need some help or advice with its removal or suggestions for new tree planting on infected sites then get in touch at info@arborlinetreecare.co.uk.