Honey fungus affects the roots, trunks and stems of plants. A creamy white sheet of fungus grows between bark and the plant tissue beneath it. The fungus smells very much like everyday mushrooms.
The fungus also develops fungal strands called rhizomorphs. These are black and could easily be mistaken for old tree roots but for the fact that they are hollow. Like roots they can be thick or thin and consist of one or several branched strands. They will feed on the host plant but will also grow through the soil until they find another source of food - they can grow at a rate of up to 1 metre a year.
Generally the infected plant will begin to wilt/die back. The rate of decline can vary substantially - plants can die rapidly but equally others may take several years to die. Some plants, especially Conifers, will leak resin from around the base of the plant.
Occasionally groups of honey coloured toadstools can grow at the base of infected plants during the late summer or early autumn.
Treatment and control
General tips: There is no reliable chemical treatment for this disease. Control must be through garden hygiene. Dig out infected plants and their root systems. Destroy the infected material. Replant with fungus resistant replacements for example Yew, Mallow, Beech, Box, Clematis, Choisya, Hebe or Bamboo.