Honey fungus is a fungal disease that affects many woody plants, the disease spreads underground by means of Rhizomorphs that look like strong black ‘boot laces’, affected wood has sheets of white mycelium that smells strongly of mushrooms.
Symptoms above ground include a general weakness of the affected plants which show poor colour and weak growth, the plants may die slowly over time or very quickly, especially if the growing environment causes further stress – a prolonged drought for example. The stems of affected plants may split and crack near the base of the stem, sometime accompanied briefly by clusters of light brown toadstools.
There are no chemical methods of controlling Honey fungus, the best approach is to try and limit its spread. This may be achieved by removing any affected plants including the roots and either sending them to landfill or burning them. Installing a strong, vertical physical barrier around the affected area (such as strong pond liner) will stop the spread, the barrier should protrude 5-10cm above the soil level to be completely effective.
While no plants can be considered truly resistant to Honey Fungus, there are a number of hedging species that rarely succumb to the disease that you may like to consider as replacements. These include Yew, Box, Griselinia, Hypericum, Potentilla, Alder and Cotton Lavender.