Garden Pests Series: H…

…is for Honey Fungus.

Since I was on site yesterday with our head Landscape Architect and as a result was unable to compose the next instalment of the Garden Pests Series, I’m treating you to one today! This parasitic fungi is another danger in the garden where there is no chemical treatment currently available to combat it. So take it from me, it can be a serious problem. So for more detailed information on honey fungus and what you can do to treat any affected plants and even prevent it from occurring, then please read on.

Also known by its Latin genus of Armillaria, honey fungus are parasitic by nature. As a result, they live on trees and certain shrubs. It can affect numerous plants, such as apples, wisteria, rhododendrons and a large number of conifers. Perhaps more worrying, though, most trees and shrubs found in many gardens can succumb to this potentially-destructive pathogen.

It is notoriously difficult to diagnose accurately, as symptoms that plants have when infested with honey fungus are often confused with other problems. However, if you are concerned about honey fungus, here are some signs you should look out for, which may be indications of the disease:

• Leaves will discolour to a dark brown and fall from their trees;
• Any blossoms will die back;
• If infecting a fruit tree, the fruit will become wrinkled and may discolour;
• Affected areas may excrete a smily white substance;
• Leaves may not appear on deciduous trees during the Springtime; and,
• Woody plants die back and may defoliate quickly.

Its notoriety in diagnosis difficulty is apparent here, and a couple of these symptoms are also present in another nuisance featured in our Garden Pests Series: fireblight, caused by Erwinia amlovora. However, a clear indicator of honey fungus is the presence of strands of the fungus in the soil surrounding affected plants, which are thick and black in appearance, often described as bootlaces. Being a fungus, the fruit body is a mushroom; this is most visible during the Autumn and a sticky ooze may be present at the stems.

Honey fungus isn’t just a single species; a group of fungi that are closely related are collectively known by the name. Not only this, they can live for a very long time, and form some of the largest organisms on Earth. It lives in dead tree stumps and one of the most worrying factors is that it can spread to healthy plants nearby. It can also remain in soil for years, if it is allowed to establish itself.

Therefore, it is vitally important you do what you can to stop this from happening. As mentioned before, there are no chemical treatments available at this moment, but organic means are known to be somewhat effective. If you see any diseased plants, remove them and dig the roots out as far as you can. In addition, do not replant for at least a year afterwards. When you do replant, do so with resistant plants; oak, beech and yew are just three that come to mind. Also, remove and replace the soil around any affected plants. Finally, as honey fungus is capable of living in dead trees, have any large stumps removed from your garden and disposed of.

A prevention method to stop and transmittance of the pathogen is the sterilisation of any garden tools used for the removal of infected material in a household bleach solution.