Autumn Fungus Walk
Some 20 Society members enjoyed a fungus walk in Dulwich Park in mid-October. The park is home to an astonishing number of mushrooms, brackets, jellies and slime moulds, reflecting its origin as former countryside and home to many ancient as well as more recently planted trees. Our excellent guide was Fabrice Boltho, who leads fungus identification for the South London Botanical Institute (SLBI), and who linked many of the fungi we found to their nearby tree hosts for which they play an important, symbiotic role in feeding and protection. In a very enjoyable two-hour walk, we found over 30 types of fungus and learned a huge amount. Proceeds from the walk were donated to the SLBI.
Honey Fungus - A Silent Killer in Dulwich
The fungus from which Dulwich gardeners have most to fear is honey fungus - Armillaria mellea - that often explains the unexpected death of healthy bushes and trees. It has topped the list of disease enquiries to the Royal Horticultural Society since it started recording these in 1995; the most common recent hosts were privet, rose and viburnum.
The most obvious symptoms are death of the tree or shrub, with early signs being poor growth, cracking and bleeding bark, failure to flower and foliage discolouration. It can be diagnosed by peeling back the bark on the stem base or on roots, which will reveal a thin white layer of fungal tissue (mycelium) and/or black “bootlaces” (rhizomorphs) between the dead bark and the wood. Honey-coloured fruiting bodies - “mushrooms” - sometimes appear on the surface in the autumn. The fungus spreads by air-borne spores from the fruiting bodies, by root-to-root contact between plants and by underground rhizomorphs, those bootlaces, which can grow a metre a year.
Left untreated, plants will continue to be affected. The best treatment is to dig up and remove the diseased plant and as much of its root as possible, as well as those of any adjacent dead or dying plants; in hedges, the RHS recommends taking out plants a metre either side of the dead plant. Then leave the area fallow for 6 to 12 months, digging over regularly to break up and starve any fungal fragments and remove the rotting material that they feed on. Creating an impermeable plastic barrier around the affected area and replacing soil is an alternative, but harder work.
The RHS publishes lists of trees and shrubs that are susceptible and those that show resistance (www.rhs.org.uk/honeyfungushosts), as well as detailed advice on dealing with the problem.
Reuniting Sydenham Hill Wood & Dulwich Wood
The National Lottery Heritage Fund has awarded a £1.02m grant towards the £1.5m project to reunite the two woods under the management of the London Wildlife Trust, aimed at revitalising the 27 hectares of woodland, enhancing biodiversity and conservation, and improving the experience for visitors, volunteers and the local community. Work on the three-year project starts shortly.
The Society has been asked to raise £10,000 towards the balance of the required funding for the project and has agreed to provide £5,000 of match-funding towards this. Members of the Society will be able to contribute financially towards this important, transformational project - full details to come in the Spring 2025 Journal.
More elms for Dulwich
The Dulwich Estate has been awarded a further ten disease-resistant elm trees by Elms4London, an initiative of the Metropolitan Public Gardens Association, which will be planted in the new year. A number of these trees have been given to the Estate and the Dulwich Society in recent years, including one that the Society planted in Dulwich Picture Gallery last year to commemorate Her Majesty Queen Elizabeth II.
Elm trees were an important feature of the Dulwich landscape before the introduction of Dutch Elm Disease, a trio of fungi species spread by elm bark beetles (young and slightly older, dying elms can be seen in Gallery Road and Grange Lane). Elms provide forage for some 40 species of moth and for the White-letter Hairstreak butterfly (see Wildlife article). This spends the winter months in the egg stage in the end branches of elms, with the first instar larvae emerging in March to feed on elm flowers. There is a colony in Gallery Road.
2025 Garden Coach Visit - Save the Date
Our coach trip next year will be on Wednesday 11th June to Sissinghurst, the flagship National Trust Garden, and Pashley Manor, one of the finest gardens in England. Details of the visit and how to book will be in the 2025 Spring Journal and the Open Gardens brochure, both out in early March.