New RHS planting list to help tackle number one garden disease

New research from the Royal Horticultural Society (RHS) reveals how gardeners can manage honey fungus, the most popular plant complaint in UK gardens. A new list which advises on plants to avoid if the disease is present on your plot comes as the charity prepares for a surge in enquiries after the dry summer.

Honey fungus, which is often diagnosed at the end of summer when trees and shrubs suddenly die back, or at the start of autumn when honey-coloured toadstools appear, attacks and kills the roots of many woody and perennial plants. These plants require removal but the disease is extremely hard to eradicate as it lives within extensive root systems underground and can spread to nearby and replacement plants.

To understand which plants were prone to the disease, a team of RHS pathologists compared more than 5,000 records of confirmed cases of honey fungus from its members and a study into susceptibility by the University of California. It grouped plants into three categories according to how often the disease was reported on them, adjusting the score to account for their popularity in UK gardens based on RHS data.

Plants in the Myrtales order of flowering plants – including myrtle and fuchsia – and Ericales – including camellia and heather - tended to have low susceptibility, while those in the Saxifragales – such as liquidambar and witch hazels - and Fagales – birch and sweet chestnut - were mostly highly susceptible.

The RHS is now advising gardeners that if honey fungus is diagnosed on their plot, or their neighbours’, that they consider planting those deemed to have low susceptibility, helping to limit its spread and maximise enjoyment of the plant.

Popular garden plants and their susceptibility to honey fungus include:
Low susceptibility Moderate susceptibility High susceptibility
Olive Apple Privet
Yew Maple Lilac
Laurel Prunus Leyland Cypress
Honeysuckle Magnolia Viburnum
Box Rose Hawthorn
Lavender Hornbeam Eleagnus

A complete list of plant susceptibility is available on the RHS website:

Honey fungus has topped the RHS annual pest and disease ranking for 23 years and has been exacerbated in recent years by warmer, drier summers that increase the stress levels of plants and make them more susceptible to attack from the disease. Taking into account the optimum conditions for a plant, such as soil preference and access to light, can also help to make it more resilient.

Matthew Cromey, Senior Plant Pathologist at the RHS, said: “The RHS has long advised on what plants might be best avoided if honey fungus is a known problem on your plot but this new research, for the first time, also accounts for a plant’s popularity in gardens and therefore the diseases’ likely true impact. Following the planting advice isn’t a guarantee against the disease but a sensible precautionary measure akin to practicing good plant hygiene.”

The RHS has updated its honey fungus advisory pages at where more information can be found about the various strains of disease and management techniques.
‘Susceptibility of garden trees and shrubs to Armillaria root rot’ was originally published in the journal Plant Disease.

Notes to editors

About the RHS:
The Royal Horticultural Society, the world’s leading gardening charity, was founded in 1804 by Sir Joseph Banks and John Wedgwood. Our vision is to enrich everyone’s life through plants, and make the UK a greener and more beautiful place. This aspiration underpins all that we do, from inspirational gardens and shows, through our scientific research, to our education and community programmes such as Campaign for School Gardening and Britain in Bloom. We produce key publications, hold a world-class collection of horticultural books and botanical art, and sell the very best plants and gardening gifts.

The RHS is fundraising £40m to transform our gardens, outreach and education facilities, which includes redeveloping our flagship RHS Garden Wisley and opening a new garden, RHS Garden Bridgewater, in 2020. We are solely funded by our members, visitors and supporters. For more information visit

RHS Registered Charity No. 222879/SC038262

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.